Three-phase PMSG rectification system DC voltage stabilization control based on adaptive super-spiral sliding mode and dynamic load feed-forward compensation

Abstract

The invention relates to a permanent magnet synchronous generator rectification system and a direct current voltage stabilization control method thereof. By constructing a dynamic load feed-forward compensator, dynamic feed-forward compensation is carried out on a disturbance term of the self-adaptive super-spiral sliding mode, the bus voltage recovery time is effectively shortened, and the voltage fluctuation amplitude is reduced. Meanwhile, according to the designed self-adaptive super-spiral sliding mode voltage closed-loop controller, a sign function is replaced by a continuous function, an improved self-adaptive super-spiral control law is constructed, and system buffeting is effectively reduced. On the basis of space vector pulse width modulation, the designed direct current bus current observer deduces the relation between the phase current and the bus current, the bus current is reconstructed, and reliable current observation information is provided for a dynamic load feed-forward compensator.

Description

Technical Field

[0001] This invention belongs to the field of motor control technology and relates to a three-phase permanent magnet synchronous generator rectifier system and its DC voltage regulation control method. Addressing the problems of DC bus voltage fluctuations, insufficient voltage regulation accuracy, and limited anti-interference capability that three-phase permanent magnet synchronous generator (PMSG) rectifier systems easily encounter under dynamic load disturbances, this invention provides a three-phase permanent magnet synchronous generator rectifier system that integrates DC bus current observation, dynamic load feedforward compensation, and adaptive super-helical sliding mode control. Background Technology

[0002] Permanent magnet synchronous generators (PMSGs) utilize permanent magnets to provide the magnetic field, eliminating the need for electrical excitation devices. They offer advantages such as low losses, high power density, high efficiency, and high dynamic performance. Typically, a PWM rectifier is connected to the downstream stage of a PMSG to output stable and controllable DC power, making them widely used in electric aircraft, special vehicles, flywheel energy storage, micro gas turbines, and warships. However, the generator's operating state is susceptible to load conditions, especially sudden load changes that can cause voltage fluctuations, potentially leading to system instability. Traditional external-loop voltage regulation uses only a proportional-integral controller to adjust the DC voltage. However, under sudden load changes, the bus voltage suffers from long recovery times and large fluctuation amplitudes. To improve the system's anti-interference capability and reduce voltage fluctuations, various advanced control strategies have been proposed, such as feedforward compensation control, two-degree-of-freedom control, and model predictive control. These control strategies are all designed based on known mathematical models of the system and are highly dependent on these models. However, in actual operating conditions, the motor is a complex, nonlinear model, making it difficult to establish a high-precision mathematical model. Furthermore, in complex and variable operating environments, the failure probability of bus current sensors increases significantly. As a critical sensor used in voltage regulation control, the failure of the bus current sensor will severely affect the stability and reliability of the voltage regulation control system. Summary of the Invention

[0003] To address the aforementioned problems, this invention proposes a DC voltage regulation control method for a three-phase PMSG rectifier system based on adaptive superspiral sliding mode and dynamic load feedforward compensation. The method is characterized by comprising: a DC bus current observer, a dynamic load feedforward compensator, and an adaptive superspiral sliding mode voltage closed-loop controller. The control block diagram of this system is shown below. Figure 1 As shown.

[0004] The aforementioned DC bus current observer, based on space vector pulse width modulation, derives the relationship between phase current and bus current to reconstruct the bus current. Its input is the three-phase current i. a i b i c Switch signal S a Sb S c The output of the DC bus current observer is the reconstructed DC bus current i. rec .

[0005] The load feedforward compensator calculates the quadrature-axis current feedforward component based on the relationship between electromagnetic power and load-side power balance. The disturbance term is canceled out by summing the output of the adaptive superspiral sliding mode voltage closed-loop controller. Its input is the output i of the DC bus current observer. rec External given value and the electric angular velocity ω of the generator rotor e The rotor electric angular velocity is determined by the rotor electric angle θ. e The derivative is obtained.

[0006] The aforementioned adaptive superspiral sliding mode voltage closed-loop controller is used to achieve error-free tracking of the bus voltage reference setpoint and improve the system's anti-disturbance performance, and to obtain and output the quadrature-axis current error compensation component. Its input is the bus voltage reference setpoint. and the DC bus voltage u obtained by sampling dc .

[0007] The aforementioned quadrature axis current feedforward component With cross-axis current error compensation component The summation is performed by an adder, and then by an inverter to obtain the disturbance-considered term ρ=i. dc / C quadrature axis current given .

[0008] The current regulator is used to achieve fast and accurate tracking of the direct and quadrature axis currents; its input is an external direct axis current input module. Quadrature axis current given The output of the Clark and Park converters. The reference voltage v is obtained and output. d v q .

[0009] The maximum two-vector SVPWM modulation module is used to modulate the reference voltage into a three-phase PWM signal, generating a centrally symmetrical switching sequence; its inputs are the output of the current regulator and the DC bus voltage u. dc Obtain and output the switching signal S. a S b S c .

[0010] The three-phase rectifier is used to rectify the three-phase PWM voltage into DC voltage. By controlling the on / off state of the three power transistors, the PWM rectification control of the three-phase permanent magnet synchronous generator is achieved, such as... Figure 2 As shown.

[0011] The present invention relates to a DC voltage regulation control system for a three-phase PMSG rectifier system based on adaptive superspiral sliding mode and dynamic load feedforward compensation, characterized by comprising the following steps:

[0012] S1. Construct a three-phase permanent magnet synchronous generator rectifier system, including: a three-phase permanent magnet synchronous generator, a CLARK / PARK converter, a DC bus current observer, a dynamic load feedforward compensator, an adaptive super-helical sliding mode voltage closed-loop controller, two current regulators, a maximum two-vector SVPWM modulation module, and a three-phase rectifier.

[0013] S2. Construct a DC bus current observer; the DC bus current observer includes: a DC bus current reconstruction module, a sector selection module, and a second-order low-pass filter module.

[0014] S3. Construct a dynamic load feedforward compensator; the dynamic load feedforward compensator includes: a derivative element, a multiplier, and a proportional module.

[0015] S4. Construct an adaptive superspiral sliding mode voltage closed-loop controller; the adaptive superspiral sliding mode voltage closed-loop controller includes: a subtractor and an adaptive superspiral sliding mode controller.

[0016] The DC bus current observation module in this invention is as follows: Figure 3 As shown, the specific steps are as follows:

[0017] S1. The three-phase rectifier uses maximum two-vector SVPWM modulation. Taking sector I as an example, the DC bus current is constructed in software using the digitally sampled values ​​of the phase current in each switching cycle. u4 and u6, as effective vectors, will conduct their respective bridge arms during their respective action times, and the phase current will form a current on the bus after passing through the rectifier. The zero vector represents that all upper bridge arms are conducting. According to the constraint relationship of the following formula, the equivalent current on the bus is 0, so the effect of the zero vector is not included in the reconstruction calculation.

[0018] (1)

[0019] In summary, taking the first sector as an example, the expression for bus current reconstruction within a unit switching cycle can be derived as follows:

[0020] (2)

[0021] In the formula: T4 is the duration of action of the effective vector u4; T6 is the duration of action of the effective vector u6; T s unit time period

[0022] By analogy, the bus current reconstruction formulas for the remaining five sectors can be derived.

[0023] S2. To obtain a smoother reconstruction current, a second-order low-pass filter with a narrow passband is used to process the ripple. The filter transfer function is:

[0024] (3)

[0025] In the formula: ω n ζ is the cutoff frequency; ζ is the damping coefficient, which is usually set to 0.707.

[0026] Setting the cutoff frequency too low will affect the phase of the current reconstruction when the rectifier system experiences sudden load changes, causing a significant time lag compared to the actual bus current and impacting the timeliness of feedforward control. Setting the cutoff frequency too high will not effectively filter out ripple, and the reconstructed bus current will still contain a large amount of noise. By setting a reasonable filter cutoff frequency, the reconstructed current can be filtered to obtain a relatively smooth bus current i. rec .

[0027] The dynamic load feedforward compensator in this invention is as follows: Figure 4 As shown, the design steps are as follows:

[0028] S1. Under the dq axis, when the generator is at i d In the =0 control mode, the expression for the electromagnetic power output of the generator is:

[0029] (4)

[0030] As can be seen from equation (4), when the generator operating speed is constant, only the quadrature-axis current i is changed. q This allows control over the electromagnetic power output to the rectifier.

[0031] S2. Ignoring the power loss during the rectification process of the motor system and rectifier, the electromagnetic power output by the generator is equal to the power consumed by the load side.

[0032] (5)

[0033] In the formula: i dc i is the current flowing through the load; c This is the current flowing through the bus capacitor.

[0034] According to equation (5), the bus current i can be derived. all With cross-axis current i q The relationship is expressed as:

[0035] (6)

[0036] In the formula: i all It is the sum of the capacitor current and the load current.

[0037] S3. Output i of the DC bus current observer rec With DC bus voltage setpoint After passing through the multiplier, the power consumed on the load side is obtained. The q-axis current feedforward component is then obtained according to equation (6). The expression is:

[0038] (7)

[0039] The adaptive superspiral sliding mode voltage controller in this invention is as follows: Figure 5 As shown, the design steps are as follows:

[0040] S1. First, define the voltage tracking error as:

[0041] (8)

[0042] In the formula: The DC-side voltage setpoint; u dc This is the given value for the DC side voltage.

[0043] S2. Design an adaptive superhelical algorithm, the expression of which is:

[0044] (9)

[0045] In the formula:

[0046] (10)

[0047] In the formula: δ, γ, μ, φ, ε, η, α are all constants greater than 0.

[0048] S3. According to the DC-side voltage equation and power conservation law of the PMSG rectifier system, we can obtain:

[0049] (11)

[0050] Therefore, the derivative of the sliding mode variable can be obtained as:

[0051] (12)

[0052] At this point, the disturbance term is: ρ=i dc / C. Ignoring the disturbance term, substituting equation (6) into equation (12) yields:

[0053] (13)

[0054] S4. To address the bottleneck in anti-disturbance performance caused by neglecting the disturbance term in existing technologies, and to further significantly improve the system's anti-disturbance capability and voltage control accuracy, the aforementioned disturbance term ρ is actively introduced into equation (13) to construct a complete anti-disturbance control model, the expression of which is:

[0055] (14)

[0056] As can be seen from equation (14), the disturbance term is the core consideration factor throughout different operating conditions of the system. Regardless of whether it is in steady state or a sudden load change scenario, targeted anti-disturbance measures must be taken to ensure the control effect. Specifically, in steady state, a large constant α needs to be set to provide basic anti-disturbance capability for resisting the disturbance term; when the load changes suddenly, the system dynamically increases the sliding mode gain K on the basis of α through the adaptive rate (10) to further enhance the anti-disturbance performance. It can be seen that the setting of α in steady state and the adjustment of K gain when the load changes suddenly are essentially centered around resisting the disturbance term ρ. However, a large constant α will bring excessive control gain, resulting in severe system chattering.

[0057] To address the aforementioned issues and achieve precise disturbance compensation and optimized integration of control quantities, this step further designs an adaptive super-helical sliding mode and dynamic load feedforward compensation control strategy. The q-axis current feedforward component obtained from S4 in requirement 2 is then used. Compared with S5.4 The expression for addition is:

[0058] (15)

[0059] By actively introducing a disturbance term and combining it with the superposition compensation of feedforward components, real-time suppression of load disturbances can be achieved; when the output i of the DC bus current observation module... rec =i dc When the disturbance term ρ = 0, under steady-state conditions, the influence of the disturbance term ρ does not need to be considered, and a smaller constant α can be selected. When the load changes abruptly, the control gain K is increased using the adaptive rate (10) based on this α. Under the same control parameters, this control method can reduce the bus voltage recovery time and reduce the voltage fluctuation amplitude. Attached Figure Description

[0060] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0061] Figure 1 This is a block diagram of the control structure of the method of the present invention.

[0062] Figure 2 This is a topology diagram of a three-phase permanent magnet synchronous generator control system.

[0063] Figure 3 The DC bus current observation module designed for this invention.

[0064] Figure 4 This is a schematic diagram of the dynamic load feedforward compensator designed in this invention.

[0065] Figure 5 This is a schematic diagram of the adaptive superspiral sliding mode voltage controller designed in this invention. Detailed Implementation

[0066] This invention provides a voltage stabilization control method for a three-phase permanent magnet synchronous generator, the control block diagram of which is shown below. Figure 1 The steps shown are as follows:

[0067] S1. Acquire voltage, current, and speed signals and perform coordinate transformation.

[0068] Specifically, a current sensor is used to collect the three-phase current i of the motor. a i b i c The DC bus voltage signal u is acquired using a voltage sensor. dc Incremental photoelectric encoders are used to collect motor speed and rotor position.

[0069] The collected three-phase stator current signal i a i b i c After coordinate transformation by CLARK and PARK converters, the current components i in the two-phase rotating d and q coordinate systems are obtained. d i q A constant amplitude transformation is used.

[0070] The formula for the coordinate transformation module is:

[0071] (16)

[0072] (17)

[0073] S2. Obtain the reconstructed DC bus current i using the DC bus current observation module. rec .

[0074] The three-phase rectifier uses maximum two-vector SVPWM modulation. Taking sector I as an example, the DC bus current is constructed in software using the digitally sampled values ​​of the phase current in each switching cycle. u4 and u6, as effective vectors, will conduct their respective bridge arms during their respective action times, and the phase currents will form a current on the bus after passing through the rectifier. The zero vector represents that all upper bridge arms are conducting. According to the constraint relationship of the following formula, the equivalent current on the bus is 0, so the effect of the zero vector is not included in the reconstruction calculation.

[0075] (18)

[0076] In summary, taking the first sector as an example, the expression for bus current reconstruction within a unit switching cycle can be derived as follows:

[0077] (19)

[0078] In the formula: T4 is the duration of action of the effective vector u4; T6 is the duration of action of the effective vector u6; T s The unit of time period.

[0079] Then reconstruct the DC bus current i all A smoother reconstructed current i is obtained after passing through a second-order low-pass filter. rec .

[0080] S3. Obtain the q-axis current feedforward component using a dynamic load feedforward compensator. .

[0081] Specifically, the output quantity i of the DC bus current observation module is used. rec With external voltage given module The q-axis current feedforward component is obtained after passing through a multiplier and a gain module. Gain Where the electric angular velocity ω e From electrical angle θ e It is obtained by differentiation.

[0082] S4. Obtain the quadrature-axis current error compensation component without considering the disturbance term ρ using an adaptive super-spiral sliding mode voltage controller. .

[0083] Specifically, based on the bus voltage setpoint , and the DC bus voltage signal u acquired in step S1 dc The difference is used to obtain the quadrature-axis current error compensation component after passing through an adaptive super-spiral sliding mode voltage controller. .

[0084] S5. Obtain q-axis current command.

[0085] S3 yields the q-axis current feedforward component. The q-axis current error compensation component obtained from S4 The summation is performed by an adder, followed by an inverter to obtain the q-axis current reference considering the disturbance term ρ. .

[0086] S6. Obtain the d-axis and q-axis reference voltages.

[0087] Specifically, the q-axis current given by S5 considering the disturbance term ρ is... i obtained from S1 q After passing through the subtractor, the input is given to the q-axis current regulator to obtain the q-axis reference voltage V. q External d-axis reference voltage i obtained from S1 d After passing through the subtractor, the input is given to the d-axis current regulator to obtain the d-axis reference voltage v. d .

[0088] S7. Generation of rectifier control signals

[0089] The v calculated in S6 d v q The voltage reference value in the two-phase stationary coordinate system is then obtained through coordinate transformation and input to the maximum two-vector SVPWM modulation module to generate a PWM control signal to control the rectifier.

Claims

1. A three-phase permanent magnet synchronous generator rectification system, characterized by, It comprises a DC bus current observer, a dynamic load feedforward compensator, and an adaptive super-hyper sliding mode voltage closed-loop controller. The DC bus current observer is based on space vector pulse width modulation, derives the relationship between phase current and bus current, and reconstructs the bus current. The load feedforward compensator calculates a quadrature axis current feedforward component according to the relationship between electromagnetic power and load side power balance After being summed with the output of the adaptive hyper-spiral sliding mode voltage closed-loop controller, the disturbance term of the adaptive hyper-spiral sliding mode is offset. The adaptive super-hyper sliding mode voltage closed-loop controller is used to realize the errorless tracking of the given value of bus voltage.

2. The DC voltage stabilization control method of the three-phase permanent magnet synchronous generator rectification system according to claim 1, characterized by It comprises the following steps: S1. A three-phase permanent magnet synchronous generator rectification system is built, comprising a three-phase permanent magnet synchronous generator, a CLARK, a PARK converter, a DC bus current observer, a dynamic load feedforward compensator, an adaptive super-hyper sliding mode voltage closed-loop controller, two current regulators, a maximum two-vector SVPWM modulation module, and a three-phase rectifier. S2. The DC bus current observer is constructed, comprising a DC bus current reconstruction module, a sector selection module, and a second-order low-pass filter module. S3. The dynamic load feedforward compensator is constructed, comprising a derivation link, a multiplier, and a proportional module. S4. The adaptive super-hyper sliding mode voltage closed-loop controller is constructed, comprising a subtractor, an adaptive super-hyper sliding mode controller, and an inverter.

3. The method of claim 2, wherein, The specific steps of the DC bus current observation module are as follows: S3.1 The three-phase rectifier is modulated by the maximum two-vector SVPWM. Taking the first sector as an example, the digital sampling values of the phase current in each switching period are used to construct the DC bus current in a software manner. The zero vector represents that the upper bridge arm is conducting, and according to the constraint relationship, the equivalent current on the bus is 0, so the action of the zero vector is not included in the reconstruction calculation. （1） Taking the first sector as an example, the expression for reconstructing the bus current in a unit switching period is derived as follows: （2） where: T4 is the effective vector u4 action time; T6 is the effective vector u6 action time; T s is the unit time period; The bus current reconstruction formulas in the remaining five sectors can be derived in the same way. S3.2 In order to obtain a relatively smooth reconstructed current, a second-order low-pass filter with a narrow passband is used to process the ripple. The filter transfer function is as follows: （3） where ω n is the cutoff frequency; ζ is the damping coefficient, typically set to 0.707; Setting too low cut-off frequency will affect the phase of current reconstruction when the rectification system is subjected to sudden load. Setting too high cut-off frequency cannot filter the ripple well, and the reconstructed bus current still has a lot of noise. Setting a reasonable filter cut-off frequency, the reconstructed current can get a relatively smooth bus current i rec .

4. The method of claim 2, wherein, The specific steps of the dynamic load feedforward compensator are as follows: S4.1 Under d-q axes, when the generator is controlled in i d =0 mode, the electromagnetic power output of the generator is expressed as: （4） From equation (4), when the generator operating speed is constant, only changing the quadrature axis current i q The electromagnetic power output to the rectifier can be controlled. S4.2 The power loss in the motor system and the rectification process of the rectifier is ignored, and the electromagnetic power output by the generator is equal to the power consumed on the load side. （5） where: i dc is the current flowing through the load; i c is the current flowing through the bus capacitor; From equation (5) it can be derived that the bus current i all is related to the quadrature axis current i q with the expression （6） wherein: i all is the sum of the capacitance current and the load current; S4.3 Output i of the DC bus current observer rec With the DC bus voltage given value Passing through the multiplier, the power consumed by the load side is obtained. According to formula (6), the q-axis current feedforward component is obtained , the expression is: （7） 5. The method of claim 2, wherein, The specific steps of the adaptive super-hyper sliding mode voltage controller are as follows: S5.1 First, define the tracking error of the voltage as follows: （8） In the formula: is the DC side voltage setpoint; u dc is the DC side voltage setpoint; S5.2 Design the adaptive super-hyper algorithm, whose expression is as follows: （9） In the formula: δ, γ, μ, φ, ε, η, and α are all positive constants. （10） S5.3 According to the DC side voltage equation of the PMSG rectification system and the power conservation law, the following equation can be obtained: Therefore, the derivative of the sliding mode variable is as follows: （11） S5.4 To solve the bottleneck of anti-disturbance performance caused by ignoring the disturbance term in the prior art, and to further significantly improve the anti-disturbance ability and voltage control accuracy of the system, the above disturbance term ρ is actively introduced into formula (13) to construct a complete anti-disturbance control model, whose expression is as follows: （12） The perturbation term at this time is: p = i dc / C. Neglecting the perturbation term, formula (6) is substituted into formula (12) to obtain: （13） ​ （14） It can be seen from equation (14) that the disturbance term is the core factor throughout different operating conditions of the system. Whether in steady state or load mutation scenario, anti-disturbance measures need to be taken to ensure control effect. Specifically, a larger constant α needs to be set in steady state to provide basic anti-disturbance ability for resisting the disturbance term; when the load is suddenly changed, the system dynamically increases the sliding mode gain K based on α through the adaptive rate (10) to further strengthen the anti-disturbance performance. It can be seen that the setting of α in steady state and the gain adjustment of K in load mutation are essentially around resisting the disturbance term ρ. However, a larger constant α will bring about a larger control gain, resulting in serious system chattering; To solve the above problems, an adaptive super-spiral sliding mode control strategy and dynamic load feedforward compensation control strategy are further designed to achieve precise compensation of the disturbance and optimized integration of the control quantity. The q-axis current feedforward component obtained from S4 of claim 2 is added to the expression in S5.4 in S5.4, which is expressed as: （15） By actively introducing the disturbance term and combining the superposition compensation of the feedforward component, real-time suppression of load disturbance can be realized; when the output i of the S3 DC bus current observation module of claim 2 is rec =i dc , the disturbance term ρ = 0. At this time, in the steady state working condition, a smaller constant α can be selected without considering the influence of the disturbance term ρ. In the case of load mutation, the control gain K is increased based on this α using the adaptive rate (10). Under the same control parameters, this control method can reduce the bus voltage recovery time and reduce the voltage fluctuation amplitude.

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