阅读说明：本技术 一种三相降压pfc电路并联均流控制方法 (Parallel current-sharing control method for three-phase voltage-reduction PFC circuit ) 是由 王志本 王婕 刘磊 李猛 郭小强 于 2020-04-17 设计创作，主要内容包括：本发明公开了一种三相降压功率因数校正电路并联均流控制方法,其控制方法采用多自由度多变量调节方法,无需通信线,不依赖通信,避免了通信中断或通信受到干扰会导致并联均流控制失效的问题,同时该方法属于多自由度多变量可控,在不同负载情况下实现系统稳态和动态性能协同优化控制,具有工程应用价值。(The invention discloses a parallel current-sharing control method of a three-phase voltage-reduction power factor correction circuit, which adopts a multi-degree-of-freedom multivariable regulation method, does not need a communication line, does not rely on communication, avoids the problem of failure of parallel current-sharing control caused by communication interruption or interference on communication, simultaneously belongs to multi-degree-of-freedom multivariable controllability, realizes the system steady-state and dynamic performance collaborative optimization control under different load conditions, and has engineering application value.)

1. A parallel current sharing control method for a three-phase buck PFC circuit is characterized by comprising the following steps: the method comprises the following steps:

step 1: sampling AC side input current i_a、i_b、i_c；

Step 2: sampling grid voltage u_a、u_b、u_cSampling the DC output voltage u_o；

And step 3: u. of_a、u_b、u_cOutputting u after abc/dq coordinate transformation_d、u_qAs the input of the phase-locked loop, the phase-locked loop outputs a phase angle theta;

and 4, step 4: i.e. i_a、i_b、i_cObtaining I through Clarke coordinate transformation_αAnd I_β；

And 5: DC given voltage signalAnd sampling the DC output voltage u_oBy subtracting, then by subtracting the amount of currentFinally, k is obtained through a PI controller_mThe transfer function of the PI controller isWherein k is_{p_1}Coefficient of proportionality, k_{i_1}Is an integral coefficient, k_cFor adjusting the coefficient, s isA Laplace operator;

step 6: k is a radical of_mPerforming trigonometric function operation with the phase angle theta output by the phase-locked loop to obtain a reference currentAndwhereinAnd

and 7: reference currentAnd I_αSubtracting I from the difference by PR controller_αObtaining a modulation signal m through the output quantity of N (s)/D(s)_αReference currentAnd I_βSubtracting I from the difference by PR controller_βObtaining a modulation signal m through the output quantity of N (s)/D(s)_βWherein the transfer function of the PR controller isWherein k is_{p_2}，k_{i_2}，λ₂∈ (0,1) is a control coefficient, ω₀The grid voltage fundamental angular frequency, j is the imaginary part symbol,g is the adjustment coefficient, lambda₁Is a fraction;

and 8: m is to be_αAnd m_βSix switching tubes for respectively driving three-phase voltage reduction PFC circuit by obtaining driving signals after space vector modulation (SVPWM)。

Technical Field

The invention belongs to the technical field of power electronics, and particularly relates to a parallel current sharing control method for a three-phase voltage reduction PFC circuit.

Background

In recent years, the rapid development of power electronic technology has been widely applied to the fields of military industry, electric power, communication and the like. Most power electronic devices interface with the power grid through rectifiers, early rectifiers were non-linear circuits formed by diode rectifier bridges, which produced a large amount of current harmonic pollution in the power grid. There are two main methods for suppressing harmonic generated by power electronic devices: the passive method is that a passive filter or an active filter circuit is adopted to bypass or filter out harmonic waves; the other is an active method, and harmonic suppression and power factor correction are realized by using a fully-controlled device. The active rectifier is used as one of power factor correction methods, overcomes the defects of unidirectional energy flow, low power factor, high harmonic content and the like of the traditional rectifier, and is widely applied to the industrial field. However, the conventional active rectifier has limited application due to its inherent boosting capability, a buck power factor correction circuit is required in specific industrial application fields, such as aviation current and data center systems, in order to increase system capacity and redundancy, a plurality of three-phase buck PFC modules are usually connected in parallel, and circulation current is inevitably generated between the parallel modules due to inconsistency of module hardware parameters and control performance. The current sharing control by using the inter-module communication mode is one of the solutions commonly used at present, however, such communication-based mode depends on the communication line, and the parallel current sharing control fails once the communication is interrupted or disturbed. Droop control is a common control method without communication lines, and is widely applied to power electronic converters. However, the three-phase buck PFC (power factor correction) circuit has its own characteristics, and it is impossible to directly apply droop control to the system, and in addition, droop control belongs to poor regulation, which affects the control accuracy of the system. Therefore, a parallel current sharing control method for a three-phase buck PFC circuit is needed.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a parallel current sharing control method of a three-phase buck PFC circuit, which has high control precision and does not need communication among a plurality of parallel three-phase buck PFC modules.

In order to solve the problems, the technical scheme adopted by the invention is as follows:

a parallel current sharing control method for a three-phase buck PFC circuit comprises the following steps:

step 1: sampling AC side input current i_a、i_b、i_c；

Step 2: sampling grid voltage u_a、u_b、u_cSampling the DC output voltage u_o；

And step 3: u. of_a、u_b、u_cOutputting u after abc/dq coordinate transformation_d、u_qAs the input of the phase-locked loop, the phase-locked loop outputs a phase angle theta;

and 4, step 4: i.e. i_a、i_b、i_cObtaining I through Clarke coordinate transformation_αAnd I_β；

And 5: DC given voltage signalAnd sampling the DC output voltage u_oBy subtracting, then by subtracting the amount of currentFinally, k is obtained through a PI controller_mThe transfer function of the PI controller isWherein k is_{p_1}Coefficient of proportionality, k_{i_1}Is an integral coefficient, k_cFor the adjustment coefficient, s is the laplacian operator;

step 6: k is a radical of_mPerforming trigonometric function operation with the phase angle theta output by the phase-locked loop to obtain a reference currentAndwhereinAnd

and 7: reference currentAnd I_αSubtracting I from the difference by PR controller_αObtaining a modulation signal m through the output quantity of N (s)/D(s)_αReference currentAnd I_βSubtracting I from the difference by PR controller_βObtaining a modulation signal m through the output quantity of N (s)/D(s)_βWherein the transfer function of the PR controller isWherein k is_{p_2}，k_{i_2}，λ₂∈ (0,1) is a control coefficient, ω₀The grid voltage fundamental angular frequency, j is the imaginary part symbol,g is the adjustment coefficient, lambda₁Is a fraction;

and 8: m is to be_αAnd m_βAnd obtaining driving signals after space vector modulation (SVPWM) to respectively drive six switching tubes of the three-phase voltage reduction PFC circuit.

Adopt the produced beneficial effect of above-mentioned technical scheme to lie in:

1. the method of the invention does not need a communication line and does not depend on communication, thereby avoiding the problem of failure of parallel current sharing control caused by communication interruption or interference on communication. 2. The method of the invention belongs to multivariable controllable with multiple degrees of freedom, and realizes the cooperative optimization control of the steady state and the dynamic performance of the system under different load conditions.

Drawings

FIG. 1 is a three-phase buck PFC circuit;

FIG. 2 is a schematic diagram of a single three-phase buck PFC circuit control method of the present invention;

fig. 3 is a schematic diagram of a control method of n parallel three-phase buck PFC circuits according to the present invention.

Detailed Description

The invention is described in further detail below with reference to the accompanying drawings:

the invention provides a parallel current sharing control method for a three-phase buck PFC circuit, as shown in figure 1, the three-phase buck SPF circuit of the invention comprises: comprises six switching tubes S₁-S₆Controllable bridge rectifier circuitDiode D_FInductor L_dcAnd a capacitor C_dcWherein the diode D_FA diode D connected in parallel at the output end of the bridge rectifier circuit_FNegative electrode inductor L_dcConnecting capacitor C_dcOne terminal, capacitor C_dcThe other end is connected with the anode of the diode. The input end of the three-phase voltage-reducing SPF circuit is connected with a three-phase power grid through an inductor, and the output end of the three-phase voltage-reducing SPF circuit is connected with a load resistor R_LSpecifically, 3 bridge arm input ends of a bridge rectification circuit of the three-phase voltage-reducing SPF circuit are respectively connected with three inductors L through three inductors L₁、L₂、L₃Connecting a three-phase power grid, wherein each phase voltage of the three-phase power grid is u_a、u_b、u_cAt inductor L₁、L₂、L₃Two ends of the capacitor are respectively connected in parallel with a capacitor C₁、C₂、C₃Wherein the inductance L₁＝L₂＝L₃Capacitor C₁＝C₂＝C₃。

FIG. 2 shows a method for controlling a single three-phase buck power factor correction circuit to sample the grid voltage u_a、u_b、u_cOutputting u after abc/dq coordinate transformation_d、u_qAs the input of the phase-locked loop, the phase-locked loop outputs a phase angle theta;

sampling the AC side current i_a、i_b、i_cObtaining I through Clarke coordinate transformation_αAnd I_β；

DC given voltage signalAnd sampling the DC voltage u_oBy subtracting, then by subtracting the amount of currentWherein k is_cFinally, k is obtained through a PI controller for adjusting the coefficient_mThe transfer function of the PI controller isWherein k is_{p_1}Coefficient of proportionality, k_{i_1}Is the integral coefficient, s is the laplacian operator;

k_mperforming trigonometric function operation with the phase angle theta output by the phase-locked loop to obtain a reference currentAndwhereinAnd

reference currentAnd I_αSubtracting I from the difference by PR controller_αObtaining a modulation signal m through the output quantity of N (s)/D(s)_αReference currentAnd I_βSubtracting I from the difference by PR controller_βObtaining a modulation signal m through the output quantity of N (s)/D(s)_βWherein the transfer function of the PR controller isWherein k is_{p_2}，k_{i_2}，λ₂∈ (0,1) is a control coefficient, ω₀The fundamental angular frequency of the grid voltage is,g is the adjustment coefficient, lambda₁Is a fraction;

m is to be_αAnd m_βAnd obtaining driving signals after space vector modulation (SVPWM) to respectively drive six switching tubes of the three-phase voltage reduction PFC circuit.

Fig. 3 is a schematic diagram of a control method of n three-phase buck power factor correction circuits, wherein an input and an output are respectively connected to an input alternating current bus and an output direct current bus, each circuit control scheme is the same as the scheme in fig. 2, and the parallel current sharing control of the system can be realized immediately without a communication line.

In conclusion, the parallel current-sharing control method for the three-phase voltage-reduction power factor correction circuit provided by the invention has the advantages that no communication line is needed, no communication is relied on, the problem that the parallel current-sharing control fails due to communication interruption or communication interference is avoided, and meanwhile, the system can realize stable state and dynamic performance cooperative optimization control under different load conditions due to the multi-degree-of-freedom multi-variable regulation function.