CN103441696B - A kind of cascade current transformer DC side self-voltage-stabilimethod method - Google Patents

Abstract

The invention discloses a kind of cascade current transformer DC side self-voltage-stabilimethod method, FEEDBACK CONTROL is carried out to the DC voltage of each H bridge, then on the basis of phase-shifting carrier wave, carries out carrier wave rotation.Thus carry out from voltage stabilizing when not increasing auxiliary circuit and other system extra expenses, realize the balance of cascade converter unit DC voltage.

Description

A kind of cascade current transformer DC side self-voltage-stabilimethod method

Technical field

The present invention relates to a kind of cascade structure current transformer mutually in DC voltage from method for stabilizing voltage, be intended to carry out from voltage stabilizing when not increasing any DC side auxiliary circuit, ensure the balance of unit DC voltage simultaneously.

Background technology

In the application of cascade converter, due to the imbalance of series loss and shunt loss, can cause current transformer mutually in DC voltage inconsistent.Existing method or be equipped with independent power supply circuits and carry out voltage stabilizing to each DC side; Or at DC side connecting resistance and gate-controlled switch device, carried out the balance of voltage by the loss of resistance; Or carry out balancing energy by DC bus or public exchange bus.First method adds extra circuit, not only adds volume and the complexity of whole converter system, improves cost simultaneously.Second method adds the loss of device, reduces the efficiency of system.The third method is identical with first method, adds volume and the installation cost of system, makes the flowing of system capacity become complicated simultaneously.

Summary of the invention

The invention provides a kind of cascade current transformer DC side self-voltage-stabilimethod method, carrying out from voltage stabilizing when not increasing auxiliary circuit and other system extra expenses, realizing the balance of cascade converter unit DC voltage.

The technical scheme realizing above-mentioned purpose is:

A kind of cascade current transformer DC side self-voltage-stabilimethod method, described cascade converter every by N number of H-bridge unit cascade, N >=2 and N is integer, carry out FEEDBACK CONTROL to the DC voltage of each H bridge, then on the basis of phase-shifting carrier wave, carry out carrier wave rotation.

Above-mentioned cascade current transformer DC side self-voltage-stabilimethod method, wherein, carries out FEEDBACK CONTROL to the DC voltage of each H bridge, and for A phase m H bridge, 1≤m≤N and m is integer, specifically comprises:

Under the effect of the mean value control ring of current regulator and all DC voltages, obtain the controlled quentity controlled variable U of A phase _a;

The DC voltage V of A phase m H bridge _am-dcthrough this H bridge DC side voltage control loop, obtain the feedback quantity U of control ring _adcm;

According to formula: obtain the controlled quentity controlled variable U of A phase m H-bridge unit _am, through extra pulse transmission, FEEDBACK CONTROL is realized to A phase m H bridge.

Above-mentioned cascade current transformer DC side self-voltage-stabilimethod method, wherein, under the effect of the mean value control ring of current regulator and all DC voltages, obtains the controlled quentity controlled variable U of A phase _a, specifically comprise:

According to formula:

${\stackrel{\‾}{v}}_{\mathrm{dc}}=\frac{V_{a1-\mathrm{dc}}+V_{a2-\mathrm{dc}}+...+V_{\mathrm{aN}-\mathrm{dc}}+V_{b1-\mathrm{dc}}+V_{b2-\mathrm{dc}}+...+V_{\mathrm{bN}-\mathrm{dc}}+V_{c1-\mathrm{dc}}+V_{c2-\mathrm{dc}}+...+V_{\mathrm{cN}-\mathrm{dc}}}{N*3}$

Wherein, V _a1-dc, V _a2-dc, V _aN-dcbe respectively the DC voltage of A phase first H bridge, second H bridge and N number of H bridge; V _b1-dc, V _b2-dc, V _bN-dcbe respectively the DC voltage of B phase first H bridge, second H bridge and N number of H bridge; V _c1-dc, V _c2-dc, V _cN-dcbe respectively the DC voltage of C phase first H bridge, second H bridge and N number of H bridge;

Obtain the mean value of all H-bridge unit DC voltages through the mean value control ring of described all DC voltages, obtain controlled quentity controlled variable U _dc;

Offset current i _ca, i _cb, i _ccthe dq component i of electric current is compensated through Park Transformation _d, i _q; Dq component i _d, i _qwith controlled quentity controlled variable U _dcthrough described current regulator, obtain the dq component U of reference voltage _d, U _q;

Line voltage v _sa, v _sb, v _scthe dq component v of line voltage is obtained through Park Transformation _d, v _q;

U _dwith v _dand U _qwith v _qdo with afterwards respectively, then carry out the controlled quentity controlled variable U that Parker inverse transformation obtains A phase, B phase, C phase _a, U _b, U _c.

Above-mentioned cascade current transformer DC side self-voltage-stabilimethod method, wherein, carrier wave rotation is carried out on the basis of phase-shifting carrier wave, specifically comprises:

Each H bridge start time corresponding carrier wave respectively of each phase, that is: h H bridge correspondence h carrier wave, 1≤h≤N and h is integer;

Through certain modulating wave cycle, carrier wave carries out a rotation, that is: the carrier transformation of h H bridge is h+1 carrier wave, and the carrier transformation of N number of H bridge is No. 1 carrier wave.

The invention has the beneficial effects as follows: the present invention adopts the control on extra software on Traditional control basis, by carrying out FEEDBACK CONTROL to the DC voltage of each H bridge, and carrier wave rotation is carried out on the basis of phase-shifting carrier wave, realizing carrying out from voltage stabilizing when not increasing system extra expenses, ensureing the balance of cascade converter unit DC voltage.

Accompanying drawing explanation

Fig. 1 is cascade converter system construction drawing when being applied to compensating reactive power and harmonic wave;

Fig. 2 is the FEEDBACK CONTROL block diagram of each H bridge DC side voltage in the present invention;

The carrier wave figure that when Fig. 3 is phase-shifting carrier wave, each H bridge is corresponding;

The carrier wave figure that when Fig. 4 is carrier wave rotation, each H bridge is corresponding.

Embodiment

Below in conjunction with accompanying drawing, the invention will be further described.

Current transformer adopts conventional method to carry out DC side when voltage stabilizing, and itself all can have the mean value control ring of current regulator and all DC voltages.Current regulator controls the output current of current transformer, and the mean value control ring of all DC voltages can guarantee the stable of total DC side average voltage, and current transformer many employings phase-shifting carrier wave is carried out modulating thus guaranteed that the switch subfrequency of output current is higher.But cascade converter forms (every by N number of H-bridge unit cascade, N >=2 and N is integer) by the discrepant H-bridge unit of a lot of loss, so the DC voltage of each H-bridge unit is inconsistent, thus causes system normally not run.Original method all need connect extra circuit in the DC side of each H bridge.Provided by the invention from method for stabilizing voltage only on the original basis controlled, adopt the control on extra software, comprise two main points altogether: be first that FEEDBACK CONTROL is carried out for the DC voltage of each H bridge; Next is the form changing carrier wave, and carrier wave rotation is carried out on the basis of phase-shifting carrier wave.

Referring to Fig. 1, is system construction drawing when cascade converter is applied to compensating reactive power and harmonic wave, in the present embodiment, is cascaded as example with every three H-bridge unit mutually, in Fig. 1, and v _sa, v _sb, v _scfor line voltage; i _ca, i _cb, i _ccfor offset current; V _c1-dc, V _c2-dc, V _c3-dcbe respectively the DC voltage of C phase first H bridge, second H bridge and the 3rd H bridge, other phase H-bridge unit DC voltage is analogized.

FEEDBACK CONTROL is carried out to the DC voltage of each H bridge, as shown in Figure 2, specifically comprises:

1) under the effect of the mean value control ring of current regulator and all DC voltages, A phase, B phase, C phase controlled quentity controlled variable U is separately obtained _a, U _b, U _c, specifically comprise:

According to formula:

${\stackrel{\‾}{v}}_{\mathrm{dc}}=\frac{V_{a1-\mathrm{dc}}+V_{a2-\mathrm{dc}}+...+V_{\mathrm{aN}-\mathrm{dc}}+V_{b1-\mathrm{dc}}+V_{b2-\mathrm{dc}}+...+V_{\mathrm{bN}-\mathrm{dc}}+V_{c1-\mathrm{dc}}+V_{c2-\mathrm{dc}}+...+V_{\mathrm{cN}-\mathrm{dc}}}{N*3}$

Obtain the mean value of all H-bridge unit DC voltages through the mean value control ring of all DC voltages, obtain controlled quentity controlled variable U _dc, in Fig. 2, for DC side average voltage set-point; In formula, V _a1-dc, V _a2-dc, V _aN-dcbe respectively the DC voltage of A phase first H bridge, second H bridge and N number of H bridge; V _b1-dc, V _b2-dc, V _bN-dcbe respectively the DC voltage of B phase first H bridge, second H bridge and N number of H bridge; V _c1-dc, V _c2-dc, V _cN-dcbe respectively the DC voltage of C phase first H bridge, second H bridge and N number of H bridge; In the present embodiment, N is 3;

Offset current i _ca, i _cb, i _ccthe dq component i of electric current is compensated through Park Transformation _d, i _q; Dq component i _d, i _qwith controlled quentity controlled variable U _dcthrough current regulator, obtain the dq component U of reference voltage _d, U _q, in Fig. 2, i _d ^*, i _q ^*for the given electric current of electric current loop;

Line voltage v _sa, v _sb, v _scthe dq component v of line voltage is obtained through Park Transformation _d, v _q;

U _dwith v _ddo and, U _qwith v _qdo with afterwards, then carry out the controlled quentity controlled variable U that Parker inverse transformation obtains A phase, B phase, C phase _a, U _b, U _c.

2) for A phase, B phase, C phase m H bridge separately, 1≤m≤N and m is integer; The DC voltage V of A phase, B phase, C phase m H bridge separately _am-dc, V _bm-dc, V _cm-dcthrough H bridge DC side voltage control loop corresponding separately, obtain the feedback quantity U of corresponding control ring _adcm, U _bdcm, U _cdcm, for DC side average voltage set-point;

3) according to formula: obtain the controlled quentity controlled variable U of A phase m H-bridge unit _am, through extra pulse transmission, FEEDBACK CONTROL is realized to A phase m H bridge; In like manner, the controlled quentity controlled variable U of B phase, C phase m H-bridge unit is obtained _bm, U _cm, transmitted by pulse, FEEDBACK CONTROL realized to B phase, C phase m H bridge.

Therefore, the controlled quentity controlled variable of known each H bridge is made up of two parts, for A phase m H bridge:

$U_{\mathrm{am}}=U_{\mathrm{adcm}}\left(1\right)+\frac{U_a}{N}\left(2\right)$

For the controlled quentity controlled variable of same interior different H bridge mutually, their (2) part is all identical, but the amount of (1) part is different amount, the controlled quentity controlled variable that the first part is different just serves regulating action for the consistency of DC voltage.

If but only adopt control above, the parameter of H bridge DC side voltage control loop need change along with the change of current transformer power output, when output reactive power is less than 10% full-load power, may instability be there is in system, adopt carrier wave rotation to address this problem, now control ring parameter only needs to be a fixed value.When only adopting phase-shifting carrier wave, h H bridge of each phase, by adopting same carrier wave, becomes h carrier wave herein, 1≤h≤N and h is integer.Within all years, wave frequency, peak value and shape are all identical, but h carrier wave will than h-1 carrier delay angle.When adopting carrier wave rotation, the carrier wave of each H bridge will be unfixed.

Carrier wave rotation is carried out on the basis of phase-shifting carrier wave, specifically comprises:

The corresponding carrier wave respectively of each H bridge start time of each phase, that is: h the corresponding h carrier wave of H bridge;

Through certain modulating wave cycle, carrier wave carries out a rotation, that is: the carrier transformation of h H bridge is h+1 carrier wave, and the carrier transformation of N number of H bridge is No. 1 carrier wave.In the present embodiment, N is 3, the carrier wave that during phase-shifting carrier wave as shown in Figure 3, each H bridge is corresponding; And the carrier wave that during carrier wave rotation shown in Fig. 4, each H bridge is corresponding; During beginning, the carrier wave of each phase the 1st H bridge is No. 1 carrier wave, and the carrier wave of the 2nd H bridge is No. 2 carrier waves, and the carrier wave of the 3rd H bridge is No. 2 carrier waves; Through certain modulating wave week after date, the carrier wave of each phase the 1st H bridge is No. 2 carrier waves, and the carrier wave of the 2nd H bridge is No. 3 carrier waves, and the carrier wave of the 3rd H bridge is No. 1 carrier wave; Pass through certain modulating wave week after date again, the carrier wave of each phase the 1st H bridge is No. 3 carrier waves, and the carrier wave of the 2nd H bridge is No. 1 carrier wave, and the carrier wave of the 3rd H bridge is No. 2 carrier waves; Often pass through certain modulating wave cycle, carrier wave just carries out a rotation like this.In Fig. 3, Fig. 4, y represents the amplitude of carrier wave, and t represents the time.

Above embodiment is used for illustrative purposes only, but not limitation of the present invention, person skilled in the relevant technique, without departing from the spirit and scope of the present invention, various conversion or modification can also be made, therefore all equivalent technical schemes also should belong to category of the present invention, should be limited by each claim.

Claims (2)

1. a cascade current transformer DC side self-voltage-stabilimethod method, described cascade converter every by N number of H-bridge unit cascade, N >=2 and N is integer, it is characterized in that, FEEDBACK CONTROL is carried out to the DC voltage of each H bridge, then on the basis of phase-shifting carrier wave, carries out carrier wave rotation

Carry out FEEDBACK CONTROL to the DC voltage of each H bridge, for A phase m H bridge, 1≤m≤N and m is integer, specifically comprises:

Under the effect of the mean value control ring of current regulator and all DC voltages, obtain the controlled quentity controlled variable U of A phase _a;

The DC voltage V of A phase m H bridge _am-dcthrough this H bridge DC side voltage control loop, obtain the feedback quantity U of control ring _adcm;

According to formula: obtain the controlled quentity controlled variable U of A phase m H-bridge unit _am, through extra pulse transmission, FEEDBACK CONTROL is realized to A phase m H bridge,

Under the effect of the mean value control ring of current regulator and all DC voltages, obtain the controlled quentity controlled variable U of A phase _a, specifically comprise:

According to formula:

${\stackrel{\‾}{v}}_{\mathrm{dc}}=\frac{V_{a1-\mathrm{dc}}+V_{a2-\mathrm{dc}}+...+V_{\mathrm{aN}-\mathrm{dc}}+V_{b1-\mathrm{dc}}+V_{b2-\mathrm{dc}}+...+V_{\mathrm{bN}-\mathrm{dc}}+V_{c1-\mathrm{dc}}+V_{c2-\mathrm{dc}}+...+V_{\mathrm{cN}-\mathrm{dc}}}{N*3}$

Wherein, V _a1-dc, V _a2-dc, V _aN-dcbe respectively the DC voltage of A phase first H bridge, second H bridge and N number of H bridge; V _b1-dc, V _b2-dc, V _bN-dcbe respectively the DC voltage of B phase first H bridge, second H bridge and N number of H bridge; V _c1-dc, V _c2-dc, V _cN-dcbe respectively the DC voltage of C phase first H bridge, second H bridge and N number of H bridge;

Obtain the mean value of all H-bridge unit DC voltages through the mean value control ring of described all DC voltages, obtain controlled quentity controlled variable U _dc;

Offset current i _ca, i _cb, i _ccthe dq component i of electric current is compensated through Park Transformation _d, i _q; Dq component i _d, i _qwith controlled quentity controlled variable U _dcthrough described current regulator, obtain the dq component U of reference voltage _d, U _q;

Line voltage v _sa, v _sb, v _scthe dq component v of line voltage is obtained through Park Transformation _d, v _q;

U _dwith v _dand U _qwith v _qdo with afterwards respectively, then carry out the controlled quentity controlled variable U that Parker inverse transformation obtains A phase, B phase, C phase _a, U _b, U _c.

2. cascade current transformer DC side self-voltage-stabilimethod method according to claim 1, is characterized in that, carrier wave rotation is carried out on the basis of phase-shifting carrier wave, specifically comprises:

Each H bridge start time corresponding carrier wave respectively of each phase, that is: h H bridge correspondence h carrier wave, 1≤h≤N and h is integer;

Through certain modulating wave cycle, carrier wave carries out a rotation, that is: the carrier transformation of h H bridge is h+1 carrier wave, and the carrier transformation of N number of H bridge is No. 1 carrier wave.