阅读说明：本技术 一种基于预测模型的ups系统逆变器的控制方法 (Control method of UPS system inverter based on prediction model ) 是由 李宇烨 李江伟 石瑞才 罗家勇 覃斌志 王成成 王朋 赵祖鑫 钟志东 黄翰民 杨 于 2019-11-28 设计创作，主要内容包括：本发明公开了一种基于预测模型的UPS系统逆变器的控制方法,其中,所述方法包括：分析UPS系统的逆变器的拓扑,建立所述UPS系统在离散域的数学模型,获得参考电压矢量；基于滤波器电流和负载电压对所述数学模型进行前向欧拉离散处理,获得负载电压的预测模型；将测量滤波器获得的电流以及电压矢量代入所述预测模型中,得到下一刻的电压矢量预测值；将参考电压矢量和电压矢量预测值代入目标函数中,计算获得对应的函数值；选出所述对应的函数值最小的参考电压矢量,并得到施加所述最小的参考电压矢量对应的开关信号,将所述开关信号输出作用于所述逆变器。在本发明实施例中,降低控制器设计的复杂性,提高了逆变器的工作性能。(The invention discloses a control method of a UPS system inverter based on a prediction model, wherein the method comprises the following steps: analyzing the topology of an inverter of the UPS system, establishing a mathematical model of the UPS system in a discrete domain, and obtaining a reference voltage vector; performing forward Euler discrete processing on the mathematical model based on the current of the filter and the load voltage to obtain a prediction model of the load voltage; substituting the current and the voltage vector obtained by the measuring filter into the prediction model to obtain a voltage vector prediction value of the next moment; substituting the reference voltage vector and the predicted value of the voltage vector into a target function, and calculating to obtain a corresponding function value; and selecting the reference voltage vector with the minimum corresponding function value, obtaining a switching signal corresponding to the reference voltage vector with the minimum application value, and outputting the switching signal to act on the inverter. In the embodiment of the invention, the complexity of the design of the controller is reduced, and the working performance of the inverter is improved.)

1. A method for controlling an inverter of a UPS system based on a predictive model, the method comprising:

analyzing the topology of an inverter of the UPS system, establishing a mathematical model of the UPS system in a discrete domain, and obtaining a reference voltage vector;

performing forward Euler discrete processing on the mathematical model based on the current of the filter and the load voltage to obtain a prediction model of the load voltage;

substituting the current and the voltage vector obtained by the measuring filter into the prediction model to obtain a voltage vector prediction value of the next moment;

substituting the reference voltage vector and the predicted value of the voltage vector into a target function, and calculating to obtain a corresponding function value;

and selecting the reference voltage vector with the minimum corresponding function value, obtaining a switching signal corresponding to the reference voltage vector with the minimum application value, and outputting the switching signal to act on the inverter.

2. The control method of claim 1, wherein the inverter has 8 switching states.

3. The control method of claim 2, wherein the 8 switching states of the inverter are converted into a vector form of:

wherein a ═ e^j(2π/3)；

Thus, the voltage vector of the inverter output is represented as:

wherein v is_aN,v_bNAnd v_cNRespectively representing the difference between the three-phase output point potential of the inverter and the potential of a negative N point on a command side;

similarly, the available load phase voltage vectors are represented as vectors as follows:

wherein S is_a、S_bAnd S_cSwitching signals of a bridge arm of the three-phase inverter; v. of_iA voltage vector representing an inverter output; v. of_oRepresenting a load phase voltage vector; v. of_oa,v_obAnd v_ocRespectively, the partial voltages of the load voltage on the three-phase lines.

4. The control method of claim 1, wherein the mathematical model of the UPS system in the discrete domain is:

wherein, L and C respectively represent the inductance and the capacitance of the filter; i.e. i_fIs the filter current i_oRepresenting the load current.

5. The control method of claim 1, wherein the predictive model of the load voltage is:

wherein i_fIs a filter current, T_sFor the sampling period, L and C are the inductance and capacitance of the filter, respectively, v_oAs a load phase voltage vector, v_iA voltage output for the inverter; i.e. i_f(k) And i_f(k-1) represents the filter current at the time k and k-1, respectively, i_o(k) Represents the load current at time k; v. of_i(k-1) represents the voltage vector of the inverter output at time k-1, v_o(k) And v_o(k-1) represents the load phase voltage vector T at times k and k-1, respectively_sIs the sampling period.

6. The control method according to claim 1, characterized in that the objective function is:

wherein the content of the first and second substances,

Technical Field

The invention relates to the technical field of inverter control of a UPS system, in particular to a control method of a UPS system inverter based on a prediction model.

Background

The UPS mainly comprises three parts, namely a rectifier, an inverter and a storage battery. As a kind of power electronic equipment, it is widely used as an emergency backup power source for important loads, such as computers, communication systems, emergency lighting systems, and medical equipment. Because UPS is widely and very important in application, a large number of researchers have focused on improving its performance; nowadays, UPSs are moving towards intelligence, modularity, and networking; the inverter is used as the core part of the UPS, and the performance of the inverter directly influences the working performance of the whole UPS system; therefore, during the past decades, control studies of inverters have gained wide attention from researchers; in pursuit of more superior performance, various conventional control strategies are successively applied to the inverter of the UPS system; although these conventional control methods can also achieve control objectives, there are still some problems; for example, in the PI closed-loop control, the static and dynamic characteristics of the system depend on the adjustment of PI parameters, which are very complex, time-consuming and labor-consuming in most cases; as far as these conventional methods require an external modulation module to generate the trigger pulses required by the power electronics in the inverter, no relevant literature has proposed a method for improving inverter control by eliminating the external module.

Disclosure of Invention

The invention aims to overcome the defects of the prior art, and provides a control method of a UPS system inverter based on a prediction model, which reduces the complexity of controller design and improves the working performance of the inverter.

In order to solve the above technical problem, an embodiment of the present invention provides a method for controlling an inverter of a UPS system based on a prediction model, where the method includes:

analyzing the topology of an inverter of the UPS system, establishing a mathematical model of the UPS system in a discrete domain, and obtaining a reference voltage vector;

performing forward Euler discrete processing on the mathematical model based on the current of the filter and the load voltage to obtain a prediction model of the load voltage;

substituting the current and the voltage vector obtained by the measuring filter into the prediction model to obtain a voltage vector prediction value of the next moment;

substituting the reference voltage vector and the predicted value of the voltage vector into a target function, and calculating to obtain a corresponding function value;

and selecting the reference voltage vector with the minimum corresponding function value, obtaining a switching signal corresponding to the reference voltage vector with the minimum application value, and outputting the switching signal to act on the inverter.

Optionally, the inverter has 8 switching states.

Optionally, the 8 switching states of the inverter are converted into a vector form:

wherein a ═ e^j(2π/3)；

Thus, the voltage vector of the inverter output is represented as:

wherein v is_aN,v_bNAnd v_cNRespectively representing the difference between the three-phase output point potential of the inverter and the potential of a negative N point on a command side;

similarly, the available load phase voltages are represented as vectors as follows:

wherein S is_a、S_bAnd S_cSwitching signals of a bridge arm of the three-phase inverter; v. of_iA voltage vector representing an inverter output; v. of_oRepresenting a load phase voltage vector; v. of_oa,v_obAnd v_ocRespectively, the partial voltages of the load voltage on the three-phase lines.

Optionally, the mathematical model of the UPS system in the discrete domain is:

wherein, L and C respectively represent the inductance and the capacitance of the filter; i.e. i_fIs the filter current i_oRepresenting the load current.

Optionally, the prediction model of the load voltage is:

wherein i_fIs a filter current, T_sFor the sampling period, L and C are the inductance and capacitance of the filter, respectively, v_oTo load the phase voltage, v_iA voltage output for the inverter; i.e. i_f(k) And i_f(k-1) represents the filter current at the time k and k-1, respectively, i_o(k) Represents the load current at time k; v. of_i(k-1) represents the voltage vector of the inverter output at time k-1, v_o(k) And v_o(k-1) represents the load phase voltage vector T at times k and k-1, respectively_sIs the sampling period.

Optionally, the objective function is:

wherein the content of the first and second substances,

voltage components of the reference voltage vector on a d axis and a q axis respectively; v. of_od、v_oqThe voltage components of d axis and q axis of the predicted voltage vector value are respectively.

In the embodiment of the invention, the complexity of the design of the controller can be reduced, and the working performance of the inverter is improved; the method provided by the invention has the advantages of small calculated amount, easiness in realization and high accuracy, and is a control method capable of effectively improving the safety and reliability of the UPS system.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a flowchart illustrating a method for controlling an inverter of a UPS system based on a prediction model according to an embodiment of the present invention;

fig. 2 is a schematic structural composition diagram of a control system of a UPS system inverter based on a prediction model in an embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.