A control method for reducing direct current side voltage fluctuation of a permanent magnet synchronous generator system

Abstract

The application discloses a control method for reducing DC side voltage fluctuation of a permanent magnet synchronous generator system, and aims at problems of the permanent magnet synchronous generator system under traditional double closed-loop control, such as large output voltage fluctuation when the load changes, slow dynamic response and the like, and proposes a load current disturbance observer based on a supercoil algorithm, and feeds forward disturbance obtained by the disturbance observer to an output end of a voltage outer loop, so as to improve the anti-disturbance ability of the output voltage to the load change. In addition, in order to ensure the followability and robustness of the system, a two-degree-of-freedom PI controller based on the internal model control principle is used to replace the traditional voltage outer loop PI controller. The control method disclosed by the application does not need to increase the cost of additional hardware, and the control principle is simple, and has better dynamic performance and the ability of resisting load disturbance than the traditional double closed-loop control.

Description

Technical Field

[0001] This invention relates to the field of permanent magnet synchronous generator technology, and mainly to a control method for reducing DC-side voltage fluctuations in a permanent magnet synchronous generator system. Background Technology

[0002] With the continuous advancement of permanent magnet materials and power electronics technology, the performance of permanent magnet synchronous motors (PMSMs) has been significantly improved. Compared with electrically excited synchronous generators and doubly-fed induction generators, PMSMs have advantages such as high power density, small size, and light weight, and have been widely used in wind turbine generators, flywheel energy storage, special vehicles, warships, and micro gas turbines. A PWM rectifier power generation system based on a PMSM should be capable of providing power support to the system load in a standalone configuration, which places higher demands on the quality of the output voltage of the PMSM system.

[0003] Currently, the most widely used voltage-current dual closed-loop control suffers from poor control performance due to output voltage fluctuations that occur with load variations. To suppress voltage fluctuations and improve generator performance, the most direct approach is to increase the controller gain. However, increasing the control gain leads to decreased system stability, making it difficult to achieve the desired control effect. Two-degree-of-freedom control can resolve the conflict between system stability and robustness, increasing the system's disturbance rejection capability to some extent. Furthermore, advanced control algorithms such as nonlinear sliding mode control, model predictive control, and feedforward control have been proposed to improve generator performance. Among these, feedforward compensation has emerged as a simple and readily implementable method. Summary of the Invention

[0004] Objective: To address the problems existing in the background technology, this invention provides a control method for reducing DC-side voltage fluctuations in permanent magnet synchronous generator systems. Specifically, addressing the issues of large output voltage fluctuations and slow dynamic response under load changes in traditional dual-loop control, this invention proposes a disturbance observer based on a superspiral algorithm. An observation model is constructed using the load current as the disturbance quantity, and the disturbance quantity is fed forward to the output of the outer voltage loop to improve the output voltage's immunity to load changes. Furthermore, to improve system tracking performance and robustness, the outer voltage loop employs a two-degree-of-freedom PI controller based on the internal model control principle.

[0005] Technical solution: To achieve the above objectives, the technical solution adopted by this invention is as follows:

[0006] A control method for reducing DC-side voltage fluctuations in a permanent magnet synchronous generator system includes the following steps:

[0007] Step S1: Based on the power balance equation of the permanent magnet synchronous generator, construct a disturbance observer based on the superspiral algorithm with the load current as the disturbance quantity, and obtain the feedforward value after transforming the disturbance observation value.

[0008] Step S2: Design a two-degree-of-freedom voltage outer-loop PI controller based on the internal model control principle to obtain the voltage outer-loop output value.

[0009] Step S3: Use the feedforward value obtained in step S1 Feedforward to the output of the two-degree-of-freedom voltage outer loop PI controller, and compare it with the voltage outer loop output value obtained in step S2. The q-axis current setpoint is obtained after the combined calculation. Set the q-axis current value Input inner loop to suppress voltage fluctuations caused by load changes.

[0010] Furthermore, the permanent magnet synchronous generator system includes a permanent magnet synchronous generator, a PWM bridge rectifier, a Hall sensor for real-time acquisition of rotor position signals, a disturbance observer, a current sensor, and a voltage sensor; the permanent magnet synchronous generator is connected to the PWM bridge rectifier to realize the conversion of three-phase AC power to DC power; the current sensor is used to measure the three-phase current, and the q-axis current i is obtained after coordinate transformation. q and d-axis current i d q-axis current i q With a given value After comparison, the q-axis voltage u is output by the PI regulator. q d-axis current i d With a given value After comparison, the d-axis voltage u is output by the PI regulator. d The voltage sensor is used to measure the DC side voltage u. dc The q-axis current setpoint is output by the two-degree-of-freedom PI controller. The disturbance observer is used to observe changes in the load current and feeds the transformed observed values ​​to the output of the voltage outer loop.

[0011] Furthermore, the perturbation observer based on the superhelical algorithm is designed as follows:

[0012] The state equation for the DC side voltage is:

[0013]

[0014] In the formula: P is the DC-side voltage setpoint. loss The power consumed by the resistor and inductor; ω e ψ is the electric angular velocity of the motor. f For rotor flux linkage; i q i is the q-axis current; L C is the load current; C is the DC-side capacitor.

[0015] Treating the load current as a disturbance of the system, we get:

[0016]

[0017] In the formula: d represents the load disturbance of the system.

[0018] DC side voltage u dc And load disturbance d as state variable, q-axis current i q As input to the system, we can obtain:

[0019]

[0020] In the formula: ζ(t) is the rate of change of the load disturbance;

[0021] DC side voltage u dc Taking the load disturbance d as the observation object, the disturbance observer is designed as follows:

[0022]

[0023] The observer's error is:

[0024]

[0025] In the formula: This refers to the DC-side voltage observation error; υ represents the load disturbance observation error, g represents the gain of the disturbance observer, and υ represents the control law.

[0026] Furthermore, the sliding mode variables are designed as follows:

[0027]

[0028] The control rate of the design is:

[0029]

[0030] In the formula: sgn(s) is the sign function; k1 and k2 are the gains to be designed; v is the state variable.

[0031] Furthermore, the two-degree-of-freedom voltage outer-loop PI controller based on the internal model control principle is designed as follows:

[0032]

[0033] In the formula, C1(s) and C2(s) are used to adjust the system's tracking performance and disturbance rejection performance, respectively, and G n (s) represents the controlled object;

[0034] Q1(s) and Q2(s) are designed as follows:

[0035]

[0036] In the formula: L1(s) and L2(s) are low-pass filters, and their expressions are as follows:

[0037]

[0038] Based on the characteristics of permanent magnet synchronous generators, the filter is designed as follows:

[0039]

[0040] Therefore, the expressions for controllers C1(s) and C2(s) are as follows:

[0041]

[0042] In the formula, T0 = L q / k ip k0 = 3e / (2U) dc C), where λ1 and λ2 are adjustable parameters of the system; λ1 is used to adjust the system's tracking performance, and λ2 is used to adjust the system's disturbance rejection performance.

[0043] Furthermore, the feedforward value The calculation is as follows:

[0044]

[0045] Furthermore, the given value of the q-axis current consists of two parts, the first part being the voltage outer loop output. The second part is the feedforward value of the disturbance observer.

[0046] Furthermore, theoretically, the output value of the outer voltage loop should be zero.

[0047] Beneficial effects:

[0048] (1) The present invention provides a control method for reducing DC side voltage fluctuations in a permanent magnet synchronous generator system. The perturbation observer based on the super spiral algorithm can reduce the chattering of the observer and improve the observation accuracy.

[0049] (2) The two-degree-of-freedom voltage outer loop PI controller based on the internal model control principle designed in this invention can improve the system’s tracking performance and robustness to a certain extent.

[0050] (3) The present invention provides a control method for reducing DC side voltage fluctuations in a permanent magnet synchronous generator system. The algorithm is simple to implement and the system structure is simple. It can improve the dynamic performance of the system and its ability to resist load disturbances. Attached Figure Description

[0051] Figure 1 This is a block diagram illustrating the principle of a control method for reducing DC-side voltage fluctuations in a permanent magnet synchronous generator system provided by the present invention.

[0052] Figure 2 This is a block diagram of the perturbation observer principle based on the superspiral algorithm. Detailed Implementation

[0053] The present invention will be further described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0054] The method for reducing DC-side voltage fluctuations provided by this invention is based on a permanent magnet synchronous generator system. This system specifically includes a permanent magnet synchronous generator, a PWM bridge rectifier, a Hall sensor for real-time acquisition of rotor position signals, a current sensor, and a voltage sensor. The permanent magnet synchronous generator is connected to the PWM bridge rectifier to convert three-phase AC power to DC power. The current sensor measures the three-phase current, and after coordinate transformation, the q-axis current i is obtained. q and d-axis current i d q-axis current i q With q-axis current setpoint After comparison, the q-axis voltage u is output by the PI regulator. q d-axis current i d With d-axis current setpoint After comparison, the d-axis voltage u is output by the PI regulator. d The voltage sensor is used to measure the DC side voltage u. dc The q-axis current setpoint is output by the two-degree-of-freedom PI controller. A load current disturbance observer based on the superspiral algorithm is used to observe the change in load current and feed it forward to the output of the outer voltage loop.

[0055] Figure 1 The diagram shows the principle block diagram of a control method for reducing DC-side voltage fluctuations in a permanent magnet synchronous generator system proposed in this invention. The innovation of this invention lies in proposing a disturbance observer based on a superspiral algorithm to observe the load current and feed it forward to the output of the voltage outer loop. The voltage outer loop employs a two-degree-of-freedom PI controller based on the internal model control principle. The specific steps are as follows:

[0056] Step S1: Based on the power balance equation of the permanent magnet synchronous generator, construct a disturbance observer based on the superspiral algorithm with the load current as the disturbance quantity, and obtain the feedforward value after transforming the disturbance observation value.

[0057] Step S2: Design a two-degree-of-freedom voltage outer-loop PI controller based on the internal model control principle to obtain the voltage outer-loop output value.

[0058] Step S3: Use the feedforward value obtained in step S1 Feedforward to the output of the two-degree-of-freedom voltage outer loop PI controller, and compare it with the voltage outer loop output value obtained in step S2. The q-axis current setpoint is obtained after the combined calculation. Set the q-axis current value Input inner loop to suppress voltage fluctuations caused by load changes.

[0059] More preferably, the perturbation observer design based on the superspiral algorithm in step S1 is as follows:

[0060] The state equation for the DC side voltage is:

[0061]

[0062] In the formula: P is the DC-side voltage setpoint. loss The power consumed by the resistor and inductor; ω e ψ is the electric angular velocity of the motor. f For rotor flux linkage; i L C is the load current; C is the DC-side capacitor.

[0063] Treating the load current as a disturbance of the system, we get:

[0064]

[0065] In the formula: d represents the load disturbance of the system;

[0066] DC side voltage u dc And load disturbance d as state variable, q-axis current i q As input to the system, we can obtain:

[0067]

[0068] In the formula: ζ(t) is the rate of change of load disturbance.

[0069] DC side voltage u dc Taking the load disturbance d as the observation object, the disturbance observer is designed as follows:

[0070]

[0071] The observer's error is:

[0072]

[0073] In the formula: This refers to the DC-side voltage observation error; υ represents the load disturbance observation error; g represents the gain of the disturbance observer; and υ represents the control law.

[0074] The designed sliding mode variables are:

[0075]

[0076] The control rate of the design is:

[0077]

[0078] In the formula: sgn(s) is the sign function; k1 and k2 are the gains to be designed; v is the state variable.

[0079] A better design for a two-degree-of-freedom voltage outer-loop PI controller based on the internal model control principle is as follows:

[0080]

[0081] In the formula, C1(s) and C2(s) are used to adjust the system's tracking performance and disturbance rejection performance, respectively, and G n (s) is the controlled object; Q1(s) and Q2(s) are designed as follows:

[0082]

[0083] In the formula: L1(s) and L2(s) are low-pass filters, and their expressions are as follows:

[0084]

[0085] Based on the characteristics of permanent magnet synchronous generators, the filter is designed as follows:

[0086]

[0087] Therefore, the expressions for controllers C1(s) and C2(s) are as follows:

[0088]

[0089] In the formula, T0 = L q / k ip k0 = 3e / (2U) dc C), λ1 and λ2 are adjustable parameters of the system, where λ1 is used to adjust the system's tracking performance and λ2 is used to adjust the system's disturbance rejection performance.

[0090] A better approach is to calculate the feedforward value for the disturbance observer as follows:

[0091]

[0092] according to Figure 1 As shown in the control block diagram, the voltage outer loop uses a two-degree-of-freedom PI controller to output the voltage outer loop value. The feedforward value is obtained by calculating the observations from the disturbance observer. The sum of the two is used as the given value of the q-axis current. The current sensor detects the three-phase current values, and then obtains the current value i in the two-phase rotating coordinate system through coordinate transformation. d i q and the given values ​​of the d-axis and q-axis currents. The difference is compared and then processed by the current regulator to output the d-axis and q-axis voltage command values ​​u. d u q Finally, the modulation signal for the switching transistor is obtained through SVPWM space vector modulation.

[0093] Figure 2 The load current disturbance observer shown is based on the superspiral algorithm. It treats the load current as a system disturbance, takes the DC side voltage and load current as the observation objects, and feeds the disturbance observation value forward to the output of the voltage outer loop.

[0094] This invention provides a control method for reducing DC-side voltage fluctuations in permanent magnet synchronous generator (PMSG) systems. Addressing the problems of large output voltage fluctuations and slow dynamic response under traditional dual-loop control in PMSG systems, this invention proposes a load current disturbance observer based on a superspiral algorithm. The disturbance observed by the observer is fed forward to the output of the outer voltage loop to improve the output voltage's immunity to load changes. Compared to traditional dual-loop control methods, this method suppresses voltage fluctuations, improves the system's dynamic response speed, and enhances voltage control accuracy under load changes. Furthermore, to ensure system responsiveness and robustness, a two-degree-of-freedom PI controller based on internal model control principles replaces the traditional outer voltage loop PI controller. The proposed control method requires no additional hardware costs, has a simple control principle, and exhibits better dynamic performance and load disturbance immunity than traditional dual-loop control.

[0095] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A control method for reducing DC-side voltage fluctuations in a permanent magnet synchronous generator system, characterized in that, Includes the following steps: Step S1: Based on the power balance equation of the permanent magnet synchronous generator, construct a disturbance observer based on the superspiral algorithm with the load current as the disturbance quantity, and obtain the feedforward value after transforming the disturbance observation value. ; Step S2: Design a two-degree-of-freedom voltage outer-loop PI controller based on the internal model control principle to obtain the voltage outer-loop output value. ; Step S3: The feedforward value obtained in step S1 Feedforward to the output of the two-degree-of-freedom voltage outer loop PI controller, and compare it with the voltage outer loop output value obtained in step S2. The q-axis current setpoint is obtained after the combined calculation. Set the q-axis current value Input inner loop to suppress voltage fluctuations caused by load changes; The design of the two-degree-of-freedom voltage outer-loop PI controller based on the internal model control principle is as follows: , In the formula, C1(s) and C2(s) are used to adjust the system's tracking performance and disturbance rejection performance, respectively, and G n (s) is the controlled object; Q1(s) and Q2(s) are designed as follows: , In the formula: L1(s) and L2(s) are low-pass filters, and their expressions are as follows: , Based on the characteristics of permanent magnet synchronous generators, the filter is designed as follows: , Therefore, the expressions for controllers C1(s) and C2(s) are as follows: , In the formula, , λ1 and λ2 are adjustable parameters of the system; λ1 is used to adjust the system's tracking performance, and λ2 is used to adjust the system's disturbance rejection performance. The feedforward value The calculation is as follows: 。 2. The control method for reducing DC-side voltage fluctuations in a permanent magnet synchronous generator system according to claim 1, characterized in that, The perturbation observer based on the superspiral algorithm is designed as follows: The state equation for the DC side voltage is: , In the formula: P is the DC-side voltage setpoint. loss The power consumed by the resistor and inductor; The electric angular velocity of the motor; For rotor flux linkage; i q i is the q-axis current; L C is the load current; C is the DC-side capacitor. Treating the load current as a disturbance of the system, we get: , In the formula: d represents the load disturbance of the system. DC side voltage u dc And load disturbance d as state variable, q-axis current i q As input to the system, we can obtain: , In the formula: The rate of change of the load disturbance; DC side voltage u dc Taking the load disturbance d as the observation object, the disturbance observer is designed as follows: , The observer's error is: , In the formula: This refers to the DC-side voltage observation error; Let g be the load disturbance observation error, and g be the gain of the disturbance observer; This is a control law.

3. The control method for reducing DC-side voltage fluctuations in a permanent magnet synchronous generator system according to claim 2, characterized in that, The designed sliding mode variables are: , The control rate of the design is: , In the formula: sgn(s) is the sign function; k1 and k2 are the gains to be designed; v is the state variable.

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