阅读说明：本技术 一种单相逆变器直流宽频域纹波抑制装置及其控制方法 (Single-phase inverter direct-current broadband domain ripple suppression device and control method thereof ) 是由 罗安 李高翔 周乐明 陈燕东 姜捷 刘思怡 于 2019-09-16 设计创作，主要内容包括：本发明公开了一种单相逆变器直流宽频域纹波抑制装置及其控制方法,主要包括混合直流有源滤波器及其滑模反馈线性化控制方法,用于治理单项逆变器直流侧电流纹波,提高负荷供电质量。所述混合直流有源滤波器包括无源电感<I>L</I>和直流有源滤波器。其中,所述无源电感<I>L</I>串联在直流电源与逆变器间,与储能电容<I>C</I>构成<I>LC</I>滤波器,用于抑制直流纹波中高频成分；所述直流有源滤波器与逆变器部分相并联,并采用滑模反馈线性化控制方法,用于补偿直流纹波电流的低频成分。而所述滑模反馈线性化控制方法可将直流有源滤波器直流侧电压和输出电流作为一个整体进行控制,具有更高的控制精度和更好的系统鲁棒性。(The invention discloses a single-phase inverter direct-current broadband domain ripple suppression device and a control method thereof. The hybrid DC active filter comprises a passive inductor L And a dc active filter. Wherein the passive inductor L Connected in series between the DC power supply and the inverter and the energy storage capacitor C Form a LC The filter is used for inhibiting high-frequency components in direct-current ripples; the direct current active filter is connected with the inverter part in parallel, and a sliding mode feedback linearization control method is adopted for compensating the low-frequency component of the direct current ripple current. The sliding mode feedback linearization control method can convert the direct current side current of the direct current active filter into the direct current side currentthe voltage and the output current are controlled as a whole, and the method has higher control precision and better system robustness.)

1. a control method of a single-phase inverter DC broadband ripple suppression device is characterized in that,

The method comprises the following steps:

1) A direct current active filter based on a boost circuit is connected with an inverter part in parallel, and then a capacitor C is arranged on the direct current side of the direct current active filter and the inverter₁a filter inductance L is added between₁An LC filter is formed and used for inhibiting high-frequency components in direct-current ripples;

2) Detecting DC side voltage v of inverter_inMeasuring the DC side current i after passing through the LC filter_L1Capacitor voltage v of DC active filter_cAnd the output current i of the DC active filter_apfThen filtering the current i with a sliding average filter_L1Medium low frequency harmonic current to obtain direct side current i_L1Of the current of the first and second coils, and then using the current i_L1Subtracting the detected direct current quantity, and obtaining the instruction current i of the direct current hybrid active filter after negating the subtracted difference_ref；

3) taking x as [ x ]₁,x₂]＝[i_apf,v_c]Obtaining the capacitor voltage v of the DC active filter by feedback linear transformation_cand an output current i_apfEquivalent differential homoembryo control target z₁And z₂(ii) a Based on the control target z₁And z₂Calculated according to the following formulaA control variable u is output; and comparing the control variable u with the unit triangular carrier to generate a switching signal for switching on and off the switching tube of the direct current active filter, and switching on the switching tube if the control variable is greater than the unit triangular carrier signal, or switching off the switching tube if the control variable is not greater than the unit triangular carrier signal.

2. The method according to claim 1, wherein the method further comprises: in step 3), the formula before and after the feedback linearization conversion is as follows:

Wherein L is₂Is an inductance of a DC active filter, C₂Is a DC active filter capacitor.

3. The method for controlling the single-phase inverter direct-current wide-frequency-domain ripple suppression device according to claim 2, wherein in the step 4),

s＝e₂+c₁e₁；z_1refIs z₁reference value of (2), z_2refIs z₂A reference value of (d);

k, ε and c₁As a controller parameter, k>0,ε>0 and c₁>0；Is z_2refThe derivative of (c).

4. A single-phase inverter direct current broadband domain ripple suppression device is characterized by comprising a direct current active filter and an inverter based on a boost circuit; the direct current active filter is connected with the inverter in parallel; a filter inductor is connected between the direct current active filter and the inverter; the control process of the direct current active filter mainly comprises the following steps: comparing the control variable u with the unit triangular carrier to generate a switching signal for switching on and off a switching tube of the direct-current active filter, wherein if the control variable is greater than the unit triangular carrier signal, the switching tube is switched on, and if not, the switching tube is switched off;

z_1refIs z₁Reference value of (2), z_2refIs z₂A reference value of (d); k, ε and c₁Is a controller parameter; [ x ] of₁,x₂]＝[i_apf,v_c]；v_cIs the capacitor voltage of the direct current active filter; i.e. i_apfOutputting current for the direct current active filter; v. of_inIs the DC side voltage of the inverter; l is₂Is a direct current active filter inductor; k is a radical of>0,ε>0 and c₁>0；Is z_2refThe derivative of (c).

Technical Field

The invention belongs to the technical field of single-phase inverter direct-current ripple treatment, and particularly relates to a direct-current hybrid active filter and a feedback linearization sliding-mode control method thereof.

Technical Field

along with the development of national defense industry and new energy power generation, the single-phase inverter is more and more applied, harmonic current exists in direct current side current of the single-phase inverter, direct current low-frequency harmonic seriously harms the health and reliability of direct current side power supply, and the problem of single-phase inverter direct current side low-frequency harmonic treatment is increasingly prominent. Because the low-frequency harmonic current frequency is lower, only the filter capacitor is used for filtering the direct-current side harmonic, a larger capacitor is needed, the size of the power electronic equipment is increased, and the service life is shorter. The DC active filter is an effective device for compensating harmonic current in DC, has small volume and good filtering effect, is already applied to national defense industry, particularly aviation power systems, and has the principle that current with the same amplitude but opposite phase to the harmonic current is generated and injected into the DC side of an inverter to achieve the aim of eliminating the harmonic current. The hybrid active filter is an alternating current hybrid active filter, the alternating current harmonic suppression quality is improved by combining the passive filter and the active filter, and compared with a pure active filter, the hybrid active filter integrates the advantages of the passive filter and the active filter and has higher harmonic suppression capability.

Active filter control techniques are mainly divided into harmonic detection and active filter control. Harmonic detection is the basis of normal work of the active filter, and the rapidity, accuracy and flexibility of the harmonic detection directly influence the tracking and compensation characteristics of the active filter. Early harmonic current detection methods were implemented using analog circuits, but analog filters with large phase and amplitude errors and high accuracy were difficult to design and have been rarely used. With the development of electronic technology and computers, digital harmonic detection methods have become the mainstream. The control of the active filter generally adopts double closed-loop control of a voltage outer loop and a current inner loop, the outer loop controls the stability of the voltage at the direct current side, the inner loop controls the output current of the active filter to follow the target current, the conventional double-loop control has low control speed, and the effect of the active filter on harmonic compensation is severely limited.

disclosure of Invention

The invention aims to solve the technical problem that the prior art is insufficient, and provides a control method of a single-phase inverter direct-current broadband domain ripple suppression device.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows: a control method of a single-phase inverter direct-current broadband domain ripple suppression device comprises the following steps:

1) A direct current active filter based on a boost circuit is connected with an inverter part in parallel, and then a capacitor C is arranged on the direct current side of the direct current active filter and the inverter₁a filter inductance L is added between₁an LC filter is formed and used for inhibiting high-frequency components in direct-current ripples;

2) Detecting DC side voltage v of inverter_inMeasuring the DC side current i after passing through the LC filter_L1Capacitor voltage v of DC active filter_cAnd the output current i of the DC active filter_apfThen filtering the current i with a sliding average filter_L1Medium low frequency harmonic current to obtain direct side current i_L1Of the current of the first and second coils, and then using the current i_L1Subtracting the detected direct current quantity, and obtaining the instruction current i of the direct current hybrid active filter after negating the subtracted difference_ref；

3) Taking x as [ x ]₁,x₂]＝[i_apf,v_c]Obtaining the capacitor voltage v of the DC active filter by feedback linear transformation_cAnd an output current i_apfEquivalent differential homoembryo control target z₁And z₂(ii) a Based on the control target z₁And z₂Calculating a control variable u according to the following formula; and comparing the control variable u with the unit triangular carrier to generate a switching signal for switching on and off the switching tube of the direct current active filter, and switching on the switching tube if the control variable is greater than the unit triangular carrier signal, or switching off the switching tube if the control variable is not greater than the unit triangular carrier signal.

In step 3), the formula before and after the feedback linearization conversion is as follows:

Wherein L is₂Is an inductance of a DC active filter, C₂Is a DC active filter capacitor.

in the step 4), the step of mixing the raw materials,ε＞0,k＞0，s＝e₂+c₁e₁；z_1refis z₁Reference value of (2), z_2refIs z₂A reference value of (d); k, ε and c₁as a controller parameter, k>0,ε>0 and c₁>0；Is z_2refThe derivative of (c).

Correspondingly, the invention also provides a single-phase inverter direct-current broadband domain ripple suppression device, which comprises a direct-current active filter and an inverter based on a boost circuit; the direct current active filter is connected with the inverter in parallel; a filter inductor is connected between the direct current active filter and the inverter; the direct current is activethe control process of the filter mainly comprises the following steps: comparing the control variable u with the unit triangular carrier to generate a switching signal for switching on and off a switching tube of the direct-current active filter, wherein if the control variable is greater than the unit triangular carrier signal, the switching tube is switched on, and if not, the switching tube is switched off;ε＞0,k＞0，z_1refIs z₁Reference value of (2), z_2refIs z₂A reference value of (d); k, ε and c₁Is a controller parameter; [ x ] of₁,x₂]＝[i_apf,v_c]；v_cIs the capacitor voltage of the direct current active filter; i.e. i_apfOutputting current for the direct current active filter; v. of_inis the DC side voltage of the inverter; l is₂Is a direct current active filter inductor; k is a radical of>0,ε>0 and c₁>0；Is z_2refThe derivative of (c).

Compared with the prior art, the invention has the beneficial effects that: aiming at the problem of single-phase inverter direct current side ripple wave treatment, the LC filter and the direct current active filter are combined to obtain the direct current hybrid active filter, and the control of the direct current active filter is realized by applying a feedback linearization theory and sliding mode variable structure control.

Drawings

Fig. 1 shows a single-phase inverter grid-connected circuit with a direct-current hybrid active filter and a control block diagram thereof.

Fig. 2 is an equivalent circuit diagram of a single-phase inverter including a dc hybrid active filter.

Fig. 3 is a graph of impedance amplitude-frequency characteristics of the dc hybrid active filter.

Fig. 4 is a waveform diagram of an experiment before adding a direct current hybrid active filter.

Fig. 5 is an experimental waveform diagram after adding a dc hybrid active filter.

Detailed Description

the structure diagram of the grid-connected single-phase inverter with the direct-current hybrid active filter is shown in fig. 1. A filter inductor L is added between a DC side capacitor C of the single-phase inverter and a DC active filter, and the LC filter is composed of a capacitor C₁And an inductance L₁Forming; the DC active filter is composed of a capacitor C₁Inductance L₁And S5 and S6; the current on the inductor is i_L1The output current of the DC active filter is i_apfThe direct current after passing through the direct current hybrid active filter is i₁。

modeling is carried out on a direct current active filter based on a boost circuit, and a state equation can be obtained according to an average switch model:

Wherein u is a control signal of S5, C₂Is an active filter DC side capacitor, L₂Is an active filter inductance, v_cas a DC side capacitor C of the active filter₂Voltage, Z_apf(s) is the active filter equivalent impedance.

According to the equation (2), the dc active filter is equivalent to an impedance, the single-phase inverter is equivalent to a dc power supply and a frequency-doubled current source, and the equivalent circuit diagram of fig. 1 is shown in fig. 2. Fig. 3 shows a graph of the amplitude-frequency characteristic of the impedance of the active filter obtained from equation (2).

Selecting a state variable x ═ x₁,x₂]＝[i_apf,v_c]the output variable y is h (x) x₁Input variable u ═ D_kThe form can be obtained according to the formula (1)The equation of state:

Selecting a coordinate transformation formula:

and (3) transforming the state equation of the formula (3) by the lower coordinate to obtain a differential homomorphic state equation of the formula (3):

Where w is the new equivalent control variable.

The new output function is defined by equation (5):

y＝z₁ (6)

From equation (5), the state error is defined:

Constructing a sliding mode surface function according to an equation (5):

s＝e₂+c₁e₁ (8)

From equations (5), (7) and (8), the new equivalent control in equation (5) can be found:

Wherein, ε, c₁And k is a controller parameter.

According to equation (9), the corresponding original control quantity u is obtained:

The corresponding original control quantity u can be obtained by the expression (10), u is compared with the triangular carrier signal, if u is larger than the triangular carrier signal, S5 is conducted, S6 is disconnected, otherwise, S5 is conducted, and S6 is disconnected.

The TMS320F 28335-based single-phase inverter grid-connected experimental platform containing the direct-current hybrid active filter is built according to fig. 1 for research, and experimental results are shown in fig. 4 and fig. 5, wherein an experimental waveform diagram before the direct-current hybrid active filter is added to fig. 4, and an experimental waveform diagram after the direct-current hybrid active filter is added to fig. 5.

The results of the practical example show that the designed direct-current hybrid active filter and the feedback linearization sliding mode control can well control the second harmonic current at the direct-current side of the single-phase inverter and reduce the harmonic current at the direct-current side.