Three-vector model predictive direct power control method for doubly fed induction motors

Abstract

This invention provides a three-vector model predictive direct power control method, system, and computer storage medium for a doubly-fed induction motor (DFIG). The method includes calculating the negative conjugate of the stator-side complex power based on the voltage and flux linkage equations of the DFIG, and selecting three optimal voltage vectors to eliminate power errors. Using the constructed voltage vector relationship diagram, the difference between the negative conjugate of the complex power at the next moment and its reference value is calculated, and zero-voltage vector correlation components and effective voltage vector correlation components are defined. The action time and duty cycle of each vector are then calculated, and the switching signals corresponding to the action time and duty cycle of each vector are transmitted to the switching transistors in the converter to control the power of the DFIG. This invention achieves reasonable selection of the negative conjugate error component of the stator-side complex power and simplifies the calculation process of the action time of different voltage vectors, thereby shortening the prediction time.

Description

Technical Field

[0001] This invention belongs to the field of motor control technology, and particularly relates to a three-vector model predictive direct power control method, system, and computer storage medium for a doubly fed asynchronous motor. Background Technology

[0002] To meet the ever-increasing electricity demands of ships, all-electric ships based on electric propulsion systems have gradually become the production standard for major shipyards worldwide, and this also represents the future direction of ship development. All-electric ships represent a significant shift in shipping propulsion systems from traditional, environmentally harmful fossil fuel energy to a cleaner electric propulsion paradigm. All-electric ship propulsion systems are equipped with numerous power electronics devices, which not only enhance operational convenience and reliability but also simplify system architecture, while providing a more efficient and quieter electric drive system. However, during long voyages, the high-frequency switching operations may introduce significant potential failure risks to the power electronic converters, increasing the failure rate and maintenance costs, and potentially affecting the overall system reliability.

[0003] To address these challenges, a ship propulsion system based on a doubly-fed asynchronous motor is proposed. This system utilizes AC transmission lines and back-to-back power converters to construct a bidirectional power flow path. This approach effectively mitigates the impact of power converter failures, leverages cost-effective and mature AC circuit breakers, and reduces the ship propulsion system's dependence on DC buses, thereby improving the simplicity and effectiveness of fault protection.

[0004] Direct power control (DPC) is a commonly used method for controlling motor systems. Based on a lookup table, it reduces dependence on motor parameters, offering a simple control structure and fast dynamic performance. However, it results in variable switching frequencies and significant power ripple. Some researchers have combined the fast response of DPC with the constant switching frequency of vector control, improving steady-state performance to some extent. However, this requires adjusting numerous control parameters, making it difficult to achieve optimal control performance. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a three-vector model predictive direct power control method, system, and computer storage medium for doubly-fed asynchronous motors.

[0006] In a first aspect, the present invention provides a three-vector model predictive direct power control method for a doubly-fed asynchronous motor, comprising:

[0007] Determine the voltage and flux linkage relationship between the stator and rotor sides of a doubly-fed asynchronous motor in the dq coordinate system;

[0008] The stator-side dq current is determined based on the voltage and flux linkage relationship between the stator and rotor sides.

[0009] The stator-side complex power of the doubly-fed asynchronous motor is determined based on the stator-side dq current and stator-side dq voltage.

[0010] In the synchronous rotating dq coordinate system, the d-axis is used as the positioning axis of the voltage vector to determine the rate of change of the negative conjugate of the complex power on the stator side of the doubly fed asynchronous motor;

[0011] Based on the negative conjugate rate of change of the stator-side complex power of the doubly-fed asynchronous motor at the current moment, determine the negative conjugate of the stator-side complex power of the doubly-fed asynchronous motor at the next moment;

[0012] In a control cycle with only zero voltage vector action, determine the difference between the negative conjugate of the complex power on the stator side of the doubly fed asynchronous motor and the reference value at the next moment;

[0013] Based on the negative conjugate vector of the stator complex power of the doubly fed asynchronous motor related to the zero voltage vector and the effective voltage vector in the same direction, a voltage vector relationship diagram is constructed to determine the difference between the negative conjugate vector of the stator complex power of the doubly fed asynchronous motor and the reference value at the next moment, so as to select three optimal voltage vectors.

[0014] Construct three optimal voltage vector relationship diagrams to determine the duration and duty cycle of each vector;

[0015] The switching signal corresponding to the action time and duty cycle of each vector is transmitted to the switching transistor in the converter to control the power of the doubly fed asynchronous motor.

[0016] Optionally, determining the voltage and flux linkage relationship between the stator and rotor sides of the doubly-fed asynchronous motor in the dq coordinate system includes:

[0017] Calculate the stator-side dq voltage U using the following formula. sdq and rotor-side dq voltage U rdq :

[0018]

[0019] Among them, R s The resistance on the stator side; I sdq ψ is the stator-side dq current; sdq Stator-side flux linkage; t is time; j is the imaginary unit; ω1 is the system angular frequency; R r The resistance on the rotor side; I rdq ψ is the rotor-side dq current; rdq For rotor-side flux linkage; ω slip This is the rotor slip angular frequency; Represents the differential operator;

[0020] Calculate the stator-side flux linkage and rotor-side flux linkage using the following formulas:

[0021]

[0022] Among them, L s For stator-side inductance; L m The mutual inductance between the stator and rotor; L r The rotor-side inductance. Optionally, determining the stator-side dq current based on the voltage and flux linkage relationship between the stator and rotor sides includes:

[0023] Calculate the stator-side dq current I using the following formula. sdq :

[0024]

[0025] Among them, L r For rotor-side inductance; L m The mutual inductance between the stator and rotor; L s Stator-side inductance; ψ sdq For stator-side flux linkage; ψ rdq This refers to the rotor-side magnetic flux.

[0026] Optionally, determining the stator-side complex power of the doubly-fed asynchronous motor based on the stator-side dq current and stator-side dq voltage includes:

[0027] Calculate the stator-side complex power S of the doubly-fed asynchronous motor using the following formula:

[0028]

[0029] in, Stator-side dq current I sdq The conjugate value of U; sdq This is the stator-side dq voltage.

[0030] Optionally, the step of using the d-axis as the positioning axis of the voltage vector in the synchronously rotating dq coordinate system to determine the rate of change of the negative conjugate of the complex power on the stator side of the doubly-fed asynchronous motor includes:

[0031] The rate of change of the negative conjugate of the complex power on the stator side of a doubly-fed asynchronous motor is calculated using the following formula.

[0032]

[0033] Among them, -S * L is the negative conjugate of the complex power on the stator side of the doubly-fed asynchronous motor; m The mutual inductance between the stator and rotor; L r For rotor-side inductance; L s For stator-side inductance; U rdq This refers to the rotor-side dq voltage; The conjugate of the stator-side dq voltage; j is the imaginary unit; ω slip S is the rotor slip angular frequency; * U is the conjugate of the complex power on the stator side of the doubly-fed asynchronous motor; sdq ω1 is the stator-side dq voltage; ω1 is the system angular frequency.

[0034] Optionally, determining the negative conjugate of the stator-side complex power of the doubly-fed asynchronous motor at the next moment based on the negative conjugate rate of change of the stator-side complex power of the doubly-fed asynchronous motor at the current moment includes:

[0035] Calculate the negative conjugate of the stator-side complex power of the doubly-fed asynchronous motor at the next moment using the following formula:

[0036]

[0037] Among them, (-S * ) t+1 The negative conjugate of the complex power on the stator side of the doubly-fed asynchronous motor at time t+1; (-S * ) t The negative conjugate of the complex power on the stator side of the doubly-fed asynchronous motor at time t; T s Sampling time; It represents the rate of change of the negative conjugate of the complex power on the stator side of the doubly-fed asynchronous motor.

[0038] Optionally, determining the difference between the negative conjugate of the complex power on the stator side of the doubly-fed asynchronous motor and the reference value at the next moment, when only zero voltage vector action occurs in a control cycle, includes:

[0039] The negative conjugate of the stator-side complex power at the next moment is calculated using the following formula when only a zero voltage vector is applied during a control cycle:

[0040]

[0041] in, The negative conjugate of the stator-side complex power at time t+1 under the condition that only zero voltage vector action occurs in one control cycle; (-S * ) t The negative conjugate of the complex power on the stator side of the doubly-fed asynchronous motor at time t; T s ω is the sampling time; j is the imaginary unit; ω1 is the system angular frequency; ω slip L is the rotor slip angular frequency; s For stator-side inductance; L m The mutual inductance between the stator and rotor; L r For rotor-side inductance; U sdq This refers to the stator-side dq voltage;

[0042] The difference between the negative conjugate of the complex power on the stator side of the doubly-fed asynchronous motor and the reference value at the next moment is calculated using the following formula:

[0043]

[0044] Wherein, Δ(-S * ) t+1 The difference between the negative conjugate of the complex power on the stator side of the doubly-fed asynchronous motor at time t+1 and the reference value; (-S * ) ref U is the negative conjugate reference value for the complex power on the stator side of the doubly-fed asynchronous motor; rdq This represents the rotor-side dq voltage.

[0045] Optionally, the step involves constructing a voltage vector relationship diagram based on the negative conjugate vector of the stator complex power of the doubly-fed asynchronous motor related to the zero voltage vector and the effective voltage vector in the same direction, determining the difference between the negative conjugate vector of the stator complex power of the doubly-fed asynchronous motor and the reference value at the next moment, in order to select three optimal voltage vectors, including:

[0046] Construct the negative conjugate vector expression for the stator-side complex power related to the zero-voltage vector:

[0047]

[0048] n is the negative conjugate vector of the stator-side complex power related to the zero voltage vector;

[0049] Construct the negative conjugate vector expression for the stator-side complex power related to the effective voltage vector in the same direction:

[0050]

[0051] Among them, T i The duration of the i-th effective voltage vector;

[0052] A voltage vector relationship diagram is constructed based on the negative conjugate vector of the stator complex power of the doubly-fed asynchronous motor, which is related to the zero voltage vector and the effective voltage vector in the same direction.

[0053] Based on the voltage vector relationship diagram, determine the difference between the negative conjugate vector of the complex power on the stator side of the doubly fed asynchronous motor at the next moment and the reference value, so as to select three optimal voltage vectors.

[0054] In a second aspect, the present invention provides a three-vector model predictive direct power control system for a doubly-fed asynchronous motor, comprising:

[0055] The first determining module is used to determine the voltage and flux linkage relationship between the stator and rotor sides of the doubly fed asynchronous motor in the dq coordinate system;

[0056] The second determining module is used to determine the stator-side dq current based on the voltage and flux linkage relationship between the stator and rotor sides;

[0057] The third determining module is used to determine the stator-side complex power of the doubly-fed asynchronous motor based on the stator-side dq current and stator-side dq voltage;

[0058] The fourth determining module is used to determine the rate of change of the negative conjugate of the complex power on the stator side of the doubly-fed asynchronous motor by using the d-axis as the positioning axis of the voltage vector in the synchronously rotating dq coordinate system.

[0059] The fifth determining module is used to determine the negative conjugate of the complex power on the stator side of the doubly-fed asynchronous motor at the next moment based on the negative conjugate rate of change of the complex power on the stator side of the doubly-fed asynchronous motor at the current moment.

[0060] The sixth determination module is used to determine the difference between the negative conjugate of the complex power on the stator side of the doubly-fed asynchronous motor and the reference value at the next moment when only zero voltage vector action occurs in a control cycle.

[0061] The seventh determination module is used to construct a voltage vector relationship diagram based on the negative conjugate vector of the stator complex power of the doubly-fed asynchronous motor related to the zero voltage vector and the effective voltage vector in the same direction, and to determine the difference between the negative conjugate vector of the stator complex power of the doubly-fed asynchronous motor and the reference value at the next moment, so as to select three optimal voltage vectors.

[0062] The eighth determination module is used to construct three optimal voltage vector relationship diagrams to determine the duration and duty cycle of each vector;

[0063] The control module is used to transmit the switching signals corresponding to the action time and duty cycle of each vector to the switching transistors in the converter in order to control the power of the doubly fed asynchronous motor.

[0064] Thirdly, the present invention provides a computer-readable storage medium for storing a computer program; when the computer program is executed by a processor, it implements the steps of the three-vector model predictive direct power control method for a doubly-fed asynchronous motor described in the first aspect.

[0065] This invention provides a three-vector model predictive direct power control method, system, and computer storage medium for a doubly-fed asynchronous motor. The method combines three-vector model predictive control technology with direct power control methods, constructs a voltage vector relationship diagram, calculates the negative conjugate of the complex power on the stator side of the doubly-fed asynchronous motor, and calculates the difference between the negative conjugate vector of the complex power at the next moment and its reference value. Three optimal voltage vectors are selected to eliminate power errors, achieving reasonable selection of the negative conjugate error components of the complex power on the stator side and simplifying the calculation process of the action time of different voltage vectors. Moreover, only one prediction step is required, thus shortening the prediction time. Attached Figure Description

[0066] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0067] Figure 1 A flowchart of a three-vector model predictive direct power control method for a doubly-fed asynchronous motor provided in this embodiment of the invention;

[0068] Figure 2 A schematic diagram of the topology of a doubly-fed asynchronous motor and its control system provided in an embodiment of the present invention;

[0069] Figure 3 The equivalent circuit diagram of a doubly fed asynchronous motor in a synchronous rotating coordinate system provided in the embodiments of the present invention;

[0070] Figure 4 A voltage and power vector relationship diagram for sector 1, provided as an example in an embodiment of the present invention;

[0071] Figure 5 A block diagram of the three-vector optimization selection model for predicting direct power control of a doubly-fed asynchronous motor provided in an embodiment of the present invention;

[0072] Figure 6 This is a schematic diagram of a three-vector model predictive direct power control system for a doubly-fed asynchronous motor, provided as an embodiment of the present invention. Detailed Implementation

[0073] The technical solutions of the embodiments 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, and 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.

[0074] The purpose of this invention is to provide a three-vector model predictive direct power control method for a doubly-fed asynchronous motor, aiming to improve the reliability and control system response speed of a doubly-fed asynchronous all-electric ship propulsion system. The topology of the doubly-fed asynchronous motor and its control system is as follows: Figure 2 As shown. Figure 2 S1-S 12 Both are switching transistors; C1 and C2 are both DC bus capacitors; U dc1 and U dc2 These are the upper and lower DC bus voltages, respectively; L g and Rg These are the source-side converter inductor and resistor, respectively; i sa i sb and i sc These are the stator-side phase A, phase B, and phase C currents, respectively; i ga i gb and i gc These represent the currents of phases A, B, and C of the source-side converter, respectively; i ra i rb and i rc These are the rotor-side A-phase, B-phase, and C-phase currents, respectively.

[0075] Example 1

[0076] like Figure 1 As shown, this embodiment provides a three-vector model predictive direct power control method for a doubly-fed asynchronous motor, including:

[0077] Step 101: Determine the voltage and flux linkage relationship between the stator and rotor sides of the doubly fed asynchronous motor in the dq coordinate system.

[0078] The equivalent circuit diagram of the dq mathematical model of a doubly-fed asynchronous motor is as follows: Figure 3 As shown. Figure 3 L ls and L lr The self-inductances on the stator side and rotor side are respectively, and their expressions are L... ls =L s -L m L lr =L r -L m The superscript 's' indicates that the variables on the rotor side are equivalent to those on the stator side.

[0079] For example, the stator-side dq (axis-side) voltage U is calculated according to the following formula. sdq and rotor-side dq (shaft) voltage U rdq :

[0080]

[0081] Among them, R s The resistance on the stator side; I sdq ψ is the stator-side dq (axis-side) current; sdq The stator side flux linkage (on the dq axis); t is time; j is the imaginary unit; ω1 is the system angular frequency; R r The resistance on the rotor side; I rdq ψ is the rotor-side dq (shaft-side) current; rdq For rotor-side (dq-axis) flux linkage; ω slip This is the rotor slip angular frequency; This represents a differential operator.

[0082] Calculate the stator-side flux linkage and rotor-side flux linkage using the following formulas:

[0083]

[0084] Among them, L s For stator-side inductance; L m The mutual inductance between the stator and rotor; L r This is the rotor-side inductance.

[0085] Step 102: Determine the stator-side dq current based on the voltage and flux linkage relationship between the stator and rotor sides.

[0086] For example, the stator-side dq current I is calculated according to the following formula. sdq :

[0087]

[0088] Among them, L r For rotor-side inductance; L m The mutual inductance between the stator and rotor; L s Stator-side inductance; ψ sdq For stator-side flux linkage; ψ rdq This refers to the rotor-side magnetic flux.

[0089] Step 103: Determine the stator-side complex power of the doubly-fed asynchronous motor based on the stator-side dq current and stator-side dq voltage.

[0090] For example, the stator-side complex power S of the doubly-fed asynchronous motor is calculated according to the following formula:

[0091]

[0092] in, Stator-side dq current I sdq The conjugate value of U; sdq dq represents the stator side voltage; P and Q represent the active power and reactive power, respectively.

[0093] Step 104: In the synchronous speed rotating dq coordinate system, the d-axis is used as the positioning axis of the voltage vector to determine the rate of change of the negative conjugate of the complex power on the stator side of the doubly fed asynchronous motor.

[0094] To eliminate the influence of the rotor-side voltage conjugate value, the negative conjugate of the stator-side complex power and its derivative are calculated, and the relationship between the negative conjugate values ​​of the complex power between two adjacent time points is obtained using Euler's discretization formula. Therefore, the rate of change of complex power is calculated as follows:

[0095]

[0096] In the synchronously rotating dq coordinate system, if the d-axis is chosen as the positioning axis for the voltage vector, then U sdq It is a time-invariant vector, that is

[0097]

[0098] In a doubly-fed asynchronous motor, the resistance R at the stator and rotor terminals is typically... s and R r Since they are relatively small, they can be ignored in the calculation of the derivative of complex power, resulting in the following expression:

[0099]

[0100] in,

[0101] The rate of change of the negative conjugate of the complex power on the stator side of a doubly-fed asynchronous motor is calculated using the following formula.

[0102]

[0103] Among them, -S * L is the negative conjugate of the complex power on the stator side of the doubly-fed asynchronous motor; m The mutual inductance between the stator and rotor; L r For rotor-side inductance; L s For stator-side inductance; U rdq This refers to the rotor-side dq voltage; The conjugate of the stator-side dq voltage; j is the imaginary unit; ω slip S is the rotor slip angular frequency; * U is the conjugate of the complex power on the stator side of the doubly-fed asynchronous motor; sdq ω1 is the stator-side dq voltage; ω1 is the system angular frequency.

[0104] Step 105: Determine the negative conjugate of the complex power on the stator side of the doubly-fed asynchronous motor at the next moment based on the negative conjugate rate of change of the complex power on the stator side of the doubly-fed asynchronous motor at the current moment.

[0105] Will After discretizing the expression, the relationship between the complex power at time t+1 and the complex power at time t can be obtained. That is, the negative conjugate of the complex power on the stator side of the doubly-fed asynchronous motor at the next time can be calculated according to the following formula:

[0106]

[0107] Among them, (-S * ) t+1 The negative conjugate of the complex power on the stator side of the doubly-fed asynchronous motor at time t+1; (-S * ) tThe negative conjugate of the complex power on the stator side of the doubly-fed asynchronous motor at time t; T s Sampling time; It represents the rate of change of the negative conjugate of the complex power on the stator side of the doubly-fed asynchronous motor.

[0108] Step 106: Under the condition that only zero voltage vector is applied in a control cycle, determine the difference between the negative conjugate of the complex power on the stator side of the doubly fed asynchronous motor and the reference value at the next moment.

[0109] When only a zero-voltage vector is applied during a control cycle, the negative conjugate of the stator-side complex power of the doubly-fed asynchronous motor at the next moment is obtained. The expression is as follows:

[0110]

[0111] in, The negative conjugate of the stator-side complex power at time t+1 under the condition that only zero voltage vector action occurs in one control cycle; (-S * ) t The negative conjugate of the complex power on the stator side of the doubly-fed asynchronous motor at time t; T s ω is the sampling time; j is the imaginary unit; ω1 is the system angular frequency; ω slip L is the rotor slip angular frequency; s For stator-side inductance; L m The mutual inductance between the stator and rotor; L r For rotor-side inductance; U sdq This is the stator-side dq voltage.

[0112] Depend on expressions and The expression can be obtained as follows:

[0113]

[0114] The difference between the negative conjugate of the complex power on the stator side of the doubly-fed asynchronous motor and the reference value at the next moment is calculated using the following formula:

[0115]

[0116] Wherein, Δ(-S * ) t+1 The difference between the negative conjugate of the complex power on the stator side of the doubly-fed asynchronous motor at time t+1 and the reference value; (-S * ) ref U is the negative conjugate reference value for the complex power on the stator side of the doubly-fed asynchronous motor; rdq This represents the rotor-side dq voltage.

[0117] Step 107: Based on the negative conjugate vector of the stator complex power of the doubly-fed asynchronous motor related to the zero voltage vector and the effective voltage vector in the same direction, construct a voltage vector relationship diagram, determine the difference between the negative conjugate vector of the stator complex power of the doubly-fed asynchronous motor and the reference value at the next moment, and select three optimal voltage vectors.

[0118] In Δ(-S * ) t+1 Based on the expression, vector n is defined as the negative conjugate vector of the stator-side complex power related to the zero voltage vector; vector m is defined as the negative conjugate vector of the stator-side complex power related to the effective voltage vector in the same direction.

[0119] For example, this step includes:

[0120] Construct the negative conjugate vector expression for the stator-side complex power related to the zero-voltage vector:

[0121]

[0122] Construct the negative conjugate vector expression for the stator-side complex power related to the effective voltage vector in the same direction:

[0123]

[0124] Among them, T i The duration of the i-th effective voltage vector.

[0125] A voltage vector relationship diagram is constructed based on the negative conjugate vector of the stator complex power of the doubly fed asynchronous motor, which is related to the zero voltage vector and the effective voltage vector in the same direction.

[0126] Based on the voltage vector relationship diagram, determine the difference between the negative conjugate vector of the complex power on the stator side of the doubly fed asynchronous motor at the next moment and the reference value, so as to select three optimal voltage vectors.

[0127] By employing the constructed voltage vector relationship diagram, the (-S) at the next time step is calculated. * ) and reference value (-S * ) ref The difference between Δ(-S) * It defines the zero voltage vector correlation component n and the vector m corresponding to the effective voltage vector, and selects three optimal voltage vectors to eliminate power error.

[0128] Taking the case of n in sector 1 as an example, the voltage-power vector relationship diagram is as follows: Figure 4 As shown, the vector corresponding to the selected effective voltage vector is m. V4 and m V6 To make the negative conjugate value of the complex power at time t+1 zero, then

[0129] n = m v4 +m v6 .

[0130] Then, the duration and duty cycle of each vector are calculated as follows:

[0131]

[0132] Where θ represents n and m V4 The angle between them, V4 and V6 represent the two effective voltage vectors corresponding to the sector where n is located.

[0133] Step 108: Construct three optimal voltage vector relationship diagrams to determine the duration and duty cycle of each vector.

[0134] Step 109: The switching signal corresponding to the action time and duty cycle of each vector is transmitted to the switching transistor in the converter to control the power of the doubly fed asynchronous motor.

[0135] In steps 108-109, based on the relationship diagram constructed from the three voltage vectors, the action time T and duty cycle d of each vector are calculated. Considering that the effective voltage vector action time exceeds one control cycle, the corresponding action time is adjusted proportionally. The block diagram of the three-vector optimization selection model for predicting direct power control of a doubly-fed asynchronous motor is shown below. Figure 5 As shown. Figure 5 Middle I gdq U is the source-side converter dq current; dc U is the DC bus voltage; ref P is the reference voltage value. g and Q g These represent the active and reactive power of the source-side converter, respectively; P s and Q s These are the stator active and reactive power, respectively; P ref and Q ref These are the reference values ​​for active and reactive power, respectively; u g For control signals; s g and s l These are the switching signals for the source-side and load-side converters, respectively; ω r n is the rotor's electric angular velocity; p θ is the number of rotor pole pairs; r The rotor electrical angle is given.

[0136] In summary, the three-vector model predictive direct power control method for doubly-fed asynchronous motors provided in this embodiment combines three-vector model predictive control technology with direct power control methods. It constructs a voltage vector relationship diagram, calculates the negative conjugate of the complex power on the stator side of the doubly-fed asynchronous motor, and calculates the difference between the negative conjugate vector of the complex power at the next moment and its reference value. It selects three optimal voltage vectors to eliminate power errors, achieves reasonable selection of the negative conjugate error components of the complex power on the stator side, simplifies the calculation process of the action time of different voltage vectors, and only requires one prediction step, thus shortening the prediction time.

[0137] Example 2

[0138] Based on the same inventive concept as Embodiment 1, this embodiment provides a three-vector model predictive direct power control system for a doubly-fed asynchronous motor. Since the principle of this system in solving the problem is similar to the aforementioned three-vector model predictive direct power control method for a doubly-fed asynchronous motor, the implementation of this system can refer to the implementation of the three-vector model predictive direct power control method for a doubly-fed asynchronous motor.

[0139] like Figure 6 As shown, the three-vector model predictive direct power control system for a doubly-fed asynchronous motor includes:

[0140] The first determining module 10 is used to determine the voltage and flux linkage relationship between the stator and rotor sides of the doubly fed asynchronous motor in the dq coordinate system.

[0141] The second determining module 20 is used to determine the stator-side dq current based on the voltage and flux linkage relationship between the stator and rotor sides.

[0142] The third determining module 30 is used to determine the stator-side complex power of the doubly-fed asynchronous motor based on the stator-side dq current and stator-side dq voltage.

[0143] The fourth determining module 40 is used to determine the rate of change of the negative conjugate of the complex power on the stator side of the doubly fed asynchronous motor by using the d-axis as the positioning axis of the voltage vector in the synchronously rotating dq coordinate system.

[0144] The fifth determining module 50 is used to determine the negative conjugate of the complex power on the stator side of the doubly-fed asynchronous motor at the next moment based on the negative conjugate rate of change of the complex power on the stator side of the doubly-fed asynchronous motor at the current moment.

[0145] The sixth determining module 60 is used to determine the difference between the negative conjugate of the complex power on the stator side of the doubly fed asynchronous motor and the reference value at the next moment when only zero voltage vector action occurs in a control cycle.

[0146] The seventh determining module 70 is used to construct a voltage vector relationship diagram based on the negative conjugate vector of the stator complex power of the doubly fed asynchronous motor related to the zero voltage vector and the effective voltage vector in the same direction, and to determine the difference between the negative conjugate vector of the stator complex power of the doubly fed asynchronous motor and the reference value at the next moment, so as to select three optimal voltage vectors.

[0147] The eighth determination module 80 is used to construct three optimal voltage vector relationship diagrams to determine the action time and duty cycle of each vector.

[0148] The control module 90 is used to transmit the switching signal corresponding to the action time and duty cycle of each vector to the switching transistor in the converter in order to control the power of the doubly fed asynchronous motor.

[0149] For more detailed information on the working process of each of the above modules, please refer to the relevant content disclosed in Example 1, which will not be repeated here.

[0150] Example 3

[0151] This embodiment provides a computer device, including a processor and a memory; wherein, when the processor executes the computer program stored in the memory, it implements the steps of the three-vector model predictive direct power control method for a doubly-fed asynchronous motor described in Embodiment 1.

[0152] For a more detailed explanation of the above method, please refer to the relevant content disclosed in Example 1, which will not be repeated here.

[0153] Example 4

[0154] This embodiment provides a computer-readable storage medium for storing a computer program; when the computer program is executed by a processor, it implements the steps of the three-vector model predictive direct power control method for a doubly-fed asynchronous motor described in Embodiment 1.

[0155] For a more detailed explanation of the above method, please refer to the relevant content disclosed in Example 1, which will not be repeated here.

[0156] Example 5

[0157] This embodiment provides a computer program product, including computer-executable instructions or a computer program. When the computer-executable instructions or the computer program are executed by a processor, they implement the steps of the three-vector model predictive direct power control method for a doubly-fed asynchronous motor described in Embodiment 1.

[0158] For a more detailed explanation of the above method, please refer to the relevant content disclosed in Example 1, which will not be repeated here.

[0159] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems, devices, storage media, and computer program products disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and relevant parts can be referred to the method section.

[0160] Those skilled in the art will clearly understand that the techniques in the embodiments of the present invention can be implemented using software plus necessary general-purpose hardware platforms. Based on this understanding, the technical solutions in the embodiments of the present invention, or the parts that contribute to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in various embodiments or certain parts of the embodiments of the present invention.

[0161] In some embodiments, computer-executable instructions may take the form of programs, software, software modules, scripts, or code, written in any form of programming language (including compiled or interpreted languages, or declarative or procedural languages), and may be deployed in any form, including as stand-alone programs or as modules, components, subroutines, or other units suitable for use in a computing environment.

[0162] As an example, computer-executable instructions may, but do not necessarily, correspond to files in a file system. They may be stored as part of a file that holds other programs or data, for example, in one or more scripts in a Hyper Text Markup Language (HTML) document, in a single file dedicated to the program in question, or in multiple co-located files (e.g., files that store one or more modules, subroutines, or code sections).

[0163] As an example, computer-executable instructions can be deployed to execute on a single electronic device, or on multiple electronic devices located at one location, or on multiple electronic devices distributed across multiple locations and interconnected via a communication network.

[0164] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A three-vector model predictive direct power control method for a doubly-fed asynchronous motor, characterized in that, include: Determine the voltage and flux linkage relationship between the stator and rotor sides of a doubly-fed asynchronous motor in the dq coordinate system; The stator-side dq current is determined based on the voltage and flux linkage relationship between the stator and rotor sides. The stator-side complex power of the doubly-fed asynchronous motor is determined based on the stator-side dq current and stator-side dq voltage. In the synchronous rotating dq coordinate system, the d-axis is used as the positioning axis of the voltage vector to determine the rate of change of the negative conjugate of the complex power on the stator side of the doubly fed asynchronous motor; Based on the negative conjugate rate of change of the stator-side complex power of the doubly-fed asynchronous motor at the current moment, determine the negative conjugate of the stator-side complex power of the doubly-fed asynchronous motor at the next moment; In a control cycle with only zero voltage vector action, determine the difference between the negative conjugate of the complex power on the stator side of the doubly fed asynchronous motor and the reference value at the next moment; Based on the negative conjugate vector of the stator complex power of the doubly fed asynchronous motor related to the zero voltage vector and the effective voltage vector in the same direction, a voltage vector relationship diagram is constructed to determine the difference between the negative conjugate vector of the stator complex power of the doubly fed asynchronous motor and the reference value at the next moment, so as to select three optimal voltage vectors. Construct three optimal voltage vector relationship diagrams to determine the duration and duty cycle of each vector; The switching signal corresponding to the action time and duty cycle of each vector is transmitted to the switching transistor in the converter to control the power of the doubly fed asynchronous motor; Determining the difference between the negative conjugate of the complex power on the stator side of the doubly-fed asynchronous motor and the reference value at the next moment, under the condition that only zero voltage vector action occurs in a control cycle, includes: The negative conjugate of the stator-side complex power at the next moment is calculated using the following formula when only a zero voltage vector is applied during a control cycle: in, The negative conjugate of the stator-side complex power at time t+1 under the condition that only zero voltage vector action occurs in one control cycle; (-S * ) t The negative conjugate of the complex power on the stator side of the doubly-fed asynchronous motor at time t; T s ω is the sampling time; j is the imaginary unit; ω1 is the system angular frequency; ω slip L is the rotor slip angular frequency; s For stator-side inductance; L m The mutual inductance between the stator and rotor; L r For rotor-side inductance; U sdq This refers to the stator-side dq voltage; The difference between the negative conjugate of the complex power on the stator side of the doubly-fed asynchronous motor and the reference value at the next moment is calculated using the following formula: Wherein, Δ(-S * ) t+1 The difference between the negative conjugate of the complex power on the stator side of the doubly-fed asynchronous motor at time t+1 and the reference value; (-S * ) ref U is the negative conjugate reference value for the complex power on the stator side of the doubly-fed asynchronous motor; rdq This refers to the rotor-side dq voltage; The process involves constructing a voltage vector relationship diagram based on the negative conjugate vector of the stator complex power of the doubly-fed asynchronous motor, which is related to the zero voltage vector and the effective voltage vector in the same direction. This diagram determines the difference between the negative conjugate vector of the stator complex power of the doubly-fed asynchronous motor and the reference value at the next moment, allowing for the selection of three optimal voltage vectors, including: Construct the negative conjugate vector expression for the stator-side complex power related to the zero-voltage vector: n is the negative conjugate vector of the stator-side complex power related to the zero voltage vector; Construct the negative conjugate vector expression for the stator-side complex power related to the effective voltage vector in the same direction: Among them, T i The duration of the i-th effective voltage vector; A voltage vector relationship diagram is constructed based on the negative conjugate vector of the stator complex power of the doubly-fed asynchronous motor, which is related to the zero voltage vector and the effective voltage vector in the same direction. Based on the voltage vector relationship diagram, determine the difference between the negative conjugate vector of the complex power on the stator side of the doubly fed asynchronous motor at the next moment and the reference value, so as to select three optimal voltage vectors.

2. The three-vector model predictive direct power control method for a doubly-fed asynchronous motor according to claim 1, characterized in that, Determining the voltage and flux linkage relationship between the stator and rotor sides of the doubly-fed asynchronous motor in the dq coordinate system includes: Calculate the stator-side dq voltage U using the following formula. sdq and rotor-side dq voltage U rdq : Among them, R s The resistance on the stator side; I sdq ψ is the stator-side dq current; sdq Stator-side flux linkage; t is time; j is the imaginary unit; ω1 is the system angular frequency; R r The resistance on the rotor side; I rdq ψ is the rotor-side dq current; rdq For rotor-side flux linkage; ω slip This is the rotor slip angular frequency; Represents the differential operator; Calculate the stator-side flux linkage and rotor-side flux linkage using the following formulas: Among them, L s For stator-side inductance; L m The mutual inductance between the stator and rotor; L r This is the rotor-side inductance.

3. The three-vector model predictive direct power control method for a doubly-fed asynchronous motor according to claim 1, characterized in that, The determination of the stator-side dq current based on the voltage and flux linkage relationship between the stator and rotor sides includes: Calculate the stator-side dq current I using the following formula. sdq : Among them, L r For rotor-side inductance; L m The mutual inductance between the stator and rotor; L s Stator-side inductance; ψ sdq For stator-side flux linkage; ψ rdq This refers to the rotor-side magnetic flux.

4. The three-vector model predictive direct power control method for a doubly-fed asynchronous motor according to claim 1, characterized in that, The determination of the stator-side complex power of the doubly-fed asynchronous motor based on the stator-side dq current and stator-side dq voltage includes: Calculate the stator-side complex power S of the doubly-fed asynchronous motor using the following formula: in, Stator-side dq current I sdq The conjugate value of U; sdq This is the stator-side dq voltage.

5. The three-vector model predictive direct power control method for a doubly-fed asynchronous motor according to claim 1, characterized in that, The method of determining the rate of change of the negative conjugate of the complex power on the stator side of the doubly-fed asynchronous motor by using the d-axis as the positioning axis of the voltage vector in the synchronous rotating dq coordinate system includes: The rate of change of the negative conjugate of the complex power on the stator side of a doubly-fed asynchronous motor is calculated using the following formula. Among them, -S * L is the negative conjugate of the complex power on the stator side of the doubly-fed asynchronous motor; m The mutual inductance between the stator and rotor; L r For rotor-side inductance; L s For stator-side inductance; U rdq This refers to the rotor-side dq voltage; The conjugate of the stator-side dq voltage; j is the imaginary unit; ω slip S is the rotor slip angular frequency; * U is the conjugate of the complex power on the stator side of the doubly-fed asynchronous motor; sdq ω1 is the stator-side dq voltage; ω1 is the system angular frequency.

6. The three-vector model predictive direct power control method for a doubly-fed asynchronous motor according to claim 1, characterized in that, The step of determining the negative conjugate of the stator-side complex power of the doubly-fed asynchronous motor at the next moment based on the negative conjugate rate of change of the stator-side complex power of the doubly-fed asynchronous motor at the current moment includes: Calculate the negative conjugate of the stator-side complex power of the doubly-fed asynchronous motor at the next moment using the following formula: Among them, (-S * ) t+1 The negative conjugate of the complex power on the stator side of the doubly-fed asynchronous motor at time t+1; (-S * ) t The negative conjugate of the complex power on the stator side of the doubly-fed asynchronous motor at time t; T s Sampling time; It represents the rate of change of the negative conjugate of the complex power on the stator side of the doubly-fed asynchronous motor.

7. A three-vector model predictive direct power control system for a doubly-fed asynchronous motor, characterized in that, include: The first determining module is used to determine the voltage and flux linkage relationship between the stator and rotor sides of the doubly fed asynchronous motor in the dq coordinate system; The second determining module is used to determine the stator-side dq current based on the voltage and flux linkage relationship between the stator and rotor sides; The third determining module is used to determine the stator-side complex power of the doubly-fed asynchronous motor based on the stator-side dq current and stator-side dq voltage; The fourth determining module is used to determine the rate of change of the negative conjugate of the complex power on the stator side of the doubly-fed asynchronous motor by using the d-axis as the positioning axis of the voltage vector in the synchronously rotating dq coordinate system. The fifth determining module is used to determine the negative conjugate of the complex power on the stator side of the doubly-fed asynchronous motor at the next moment based on the negative conjugate rate of change of the complex power on the stator side of the doubly-fed asynchronous motor at the current moment. The sixth determination module is used to determine the difference between the negative conjugate of the complex power on the stator side of the doubly-fed asynchronous motor and the reference value at the next moment when only zero voltage vector action occurs in a control cycle. The seventh determination module is used to construct a voltage vector relationship diagram based on the negative conjugate vector of the stator complex power of the doubly-fed asynchronous motor related to the zero voltage vector and the effective voltage vector in the same direction, and to determine the difference between the negative conjugate vector of the stator complex power of the doubly-fed asynchronous motor and the reference value at the next moment, so as to select three optimal voltage vectors. The eighth determination module is used to construct three optimal voltage vector relationship diagrams to determine the duration and duty cycle of each vector; The control module is used to transmit the switching signals corresponding to the action time and duty cycle of each vector to the switching transistors in the converter in order to control the power of the doubly fed asynchronous motor. Determining the difference between the negative conjugate of the complex power on the stator side of the doubly-fed asynchronous motor and the reference value at the next moment, under the condition that only zero voltage vector action occurs in a control cycle, includes: The negative conjugate of the stator-side complex power at the next moment is calculated using the following formula when only a zero voltage vector is applied during a control cycle: in, The negative conjugate of the stator-side complex power at time t+1 under the condition that only zero voltage vector action occurs in one control cycle; (-S * ) t The negative conjugate of the complex power on the stator side of the doubly-fed asynchronous motor at time t; T s ω is the sampling time; j is the imaginary unit; ω1 is the system angular frequency; ω slip L is the rotor slip angular frequency; s For stator-side inductance; L m The mutual inductance between the stator and rotor; L r For rotor-side inductance; U sdq This refers to the stator-side dq voltage; The difference between the negative conjugate of the complex power on the stator side of the doubly-fed asynchronous motor and the reference value at the next moment is calculated using the following formula: Wherein, Δ(-S * ) t+1 The difference between the negative conjugate of the complex power on the stator side of the doubly-fed asynchronous motor at time t+1 and the reference value; (-S * ) ref U is the negative conjugate reference value for the complex power on the stator side of the doubly-fed asynchronous motor; rdq This refers to the rotor-side dq voltage; The process involves constructing a voltage vector relationship diagram based on the negative conjugate vector of the stator complex power of the doubly-fed asynchronous motor, which is related to the zero voltage vector and the effective voltage vector in the same direction. This diagram determines the difference between the negative conjugate vector of the stator complex power of the doubly-fed asynchronous motor and the reference value at the next moment, allowing for the selection of three optimal voltage vectors, including: Construct the negative conjugate vector expression for the stator-side complex power related to the zero-voltage vector: n is the negative conjugate vector of the stator-side complex power related to the zero voltage vector; Construct the negative conjugate vector expression for the stator-side complex power related to the effective voltage vector in the same direction: Among them, T i The duration of the i-th effective voltage vector; A voltage vector relationship diagram is constructed based on the negative conjugate vector of the stator complex power of the doubly-fed asynchronous motor, which is related to the zero voltage vector and the effective voltage vector in the same direction. Based on the voltage vector relationship diagram, determine the difference between the negative conjugate vector of the complex power on the stator side of the doubly fed asynchronous motor at the next moment and the reference value, so as to select three optimal voltage vectors.

8. A computer-readable storage medium, characterized in that, Used to store computer programs; when executed by a processor, the computer programs implement the steps of the three-vector model predictive direct power control method for a doubly fed asynchronous motor as described in any one of claims 1-6.

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