CN203562765U - Control device of current transformer current-limiting protection system - Google Patents

Abstract

The utility model discloses a control device of a current transformer current-limiting protection system. The device comprises an AC reactor, an electronic switch, a PWM rectifier, a DC reactor, and a DC filter connected in sequence. The DC filter is connected with an output filter through a PWM inverter, a correction reactor, and an inverter output transformer. The output filter accesses processor through a first AC signal sampling circuit. The processor is connected with the electronic switch, the PWM rectifier, and the PWM inverter. The processor is connected with output ends of a DC signal sampling circuit and a second AC signal sampling circuit. An input end of the DC signal sampling circuit is connected in parallel between the DC filter and the PWM inverter. An input end of the second AC signal sampling circuit is connected in parallel between the AC reactor and the electronic switch. The processor is also connected with current transformer output short-circuit hardware to lock a current foldback circuit. The device can effectively limit current and protect in an operating process of the current transformer. The device responses rapidly to resist large-current impact in instantaneous and non-instantaneous short-circuit and other operating process.

Description

Current transformer current-limiting protection system control device

Technical field

The utility model relates to a kind of high-power converter Short Circuit withstand or protection system of heavy current impact, particularly a kind of current transformer current-limiting protection system control device in when operation of being applied to.

Background technology

Bank electricity power station Converter Capacity demand constantly increases, and to its Performance And Reliability, requires more and more higher.Current transformer is the core component in electronic type bank electricity power station, has current transformer protection and Anti-interference Design for various opposing accidents or adverse circumstances in bank electric installation.The high power nonlinear load of the existing electric machinery of marine electrical equipment load, also has the sensitiveness load of high-precision electronics, communication and control class, and therefore have relatively high expectations to current transformer protective value in electronic type bank electricity power station.In actual applications current transformer require to bear electric motor starting heavy current impact, because of the overcurrent that the electric current of load variations is uprushed or various short circuit causes, can be at the fault state of resuming work fast later.The development of current transformer Over Current Protection System can strengthen current transformer robust performance and application efficiency.

Existing protection strategy mainly contains relatively relatively current-limiting circuit, software current limliting strategy of current limliting strategy, DC bus current instantaneous value of collector voltage.These technology mainly should have in the protection module of separate unit current transformer or small-power current transformer, and impact resistance is poor, are prone to response slowly and cause the very large circulation of generation between current transformer because of the difference of recovery time.

Utility model content

Technical problem to be solved in the utility model is; for prior art deficiency; a kind of current transformer current-limiting protection system control device and Current limited Control method thereof are provided; effectively current-limiting protection in current transformer running; response, resists the heavy current impact in the runnings such as instantaneous and non-instantaneous short-circuit fast.

For solving the problems of the technologies described above, the technical scheme that the utility model adopts is: a kind of current transformer current-limiting protection system control device, comprise the AC reactor, electronic switch, PWM rectifier, direct current reactor, the DC filter that connect successively, described DC filter is connected with output filter by PWM inverter, correction reactor, inversion output transformer successively; Described output filter is by the first AC signal sample circuit access processor, and described processor is connected with described electronic switch, PWM rectifier, PWM inverter; Described processor connects direct current signal sample circuit output, the second AC signal sample circuit output, between described direct current signal sample circuit input access in parallel DC filter and PWM inverter, between described the second AC signal sample circuit input described AC reactor of access in parallel and electronic switch; Described processor is also connected with current transformer output short-circuit hardware lockout current-limiting circuit, and described current transformer output short-circuit hardware lockout current-limiting circuit comprises the rectifier bridge, comparator, the d type flip flop that connect successively, and described d type flip flop outputs signal to described processor.

The Current limited Control method of current transformer current-limiting protection system control device is:

1) when short circuit or heavy current impact accident occur, AC signal sample circuit is sent into the sample rate current of PWM inverter in processor, if sample rate current mean value is greater than predefined current value in described processor, processor control PWM inverter sends failure alarm signal, processor is carried out and is interrupted, and starts software current-limiting protection subprogram;

2) whether failure judgement is removed, if remove EOI; If do not remove, enter 3);

3) definition s _kiGBT conducting on=1 o'clock PWM inverter leg, lower IGBT turn-offs, s _kiGBT conducting under=0 o'clock PWM inverter leg, upper IGBT turn-offs, wherein, and k=u, v, w, and u, v, w is three brachium pontis of corresponding PWM inverter respectively;

4), according to KCL and KVL law, obtain the inversion output loop equation under three phase static coordinate system that PWM inverter three-phase output voltage and three-phase output current are corresponding:

$\left[\begin{array}{c}{u}_{\mathrm{ou}}\\ u_{\mathrm{ov}}\\ u_{\mathrm{ow}}\end{array}\right]=(\frac{1}{C}-\frac{R_C}{L}{R}_L)\left[\begin{array}{ccc}1& 0& 0\\ 0& 1& 0\\ 0& 0& 1\end{array}\right]\left[\begin{array}{c}{i}_u\\ i_v\\ i_w\end{array}\right]-\frac{{\mathrm{<figure-callout\; id="1"\; label="R\; C\; L"\; filenames="HDA00003172273700012.png,HDA00003172273700022.png"\; state="\{\{state\}\}">R</figure-callout>}}_C}{L}\left[\begin{array}{ccc}1& 0& 0\\ 0& 1& 0\\ 0& 0& 1\end{array}\right]\left[\begin{array}{c}{u}_{\mathrm{ou}}\\ u_{\mathrm{ov}}\\ u_{\mathrm{ow}}\end{array}\right]+\frac{R_C{U}_{\mathrm{dc}}}{L}\left[\begin{array}{ccc}\frac{2}{3}& -\frac{1}{3}& \frac{2}{3}\\ -\frac{1}{3}& \frac{2}{3}& \frac{2}{3}\\ -\frac{1}{3}& -\frac{1}{3}& \frac{2}{3}\end{array}\right]\left[\begin{array}{c}{s}_u\\ s_v\\ s_w\end{array}\right],$

$\left[\begin{array}{c}{i}_u\\ i_v\\ i_w\end{array}\right]=-\frac{{\mathrm{<figure-callout\; id="1"\; label="R\; L\; L"\; filenames="HDA00003172273700012.png,HDA00003172273700022.png"\; state="\{\{state\}\}">R</figure-callout>}}_L}{L}\left[\begin{array}{ccc}1& 0& 0\\ 0& 1& 0\\ 0& 0& 1\end{array}\right]\left[\begin{array}{c}{i}_u\\ i_v\\ i_w\end{array}\right]-\frac{1}{\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HDA00003172273700012.png,HDA00003172273700022.png"\; state="\{\{state\}\}">L</figure-callout>}}\left[\begin{array}{ccc}1& 0& 0\\ 0& 1& 0\\ 0& 0& 1\end{array}\right]\left[\begin{array}{c}{u}_{\mathrm{ou}}\\ u_{\mathrm{ov}}\\ u_{\mathrm{ow}}\end{array}\right]+\frac{U_{\mathrm{dc}}}{L}\left[\begin{array}{ccc}\frac{2}{3}& -\frac{1}{3}& \frac{2}{3}\\ -\frac{1}{3}& \frac{2}{3}& \frac{2}{3}\\ -\frac{1}{3}& -\frac{1}{3}& \frac{2}{3}\end{array}\right]\left[\begin{array}{c}{s}_u\\ s_v\\ s_w\end{array}\right],$

Wherein, u _ou, u _ov, u _owfor the three-phase output phase voltage of output filter, i _u, i _v, i _wfor PWM inverter output current phase, L is for proofreading and correct reactor equivalent inductance value, R _lfor inversion output transformer equivalent inductance value, L=R _l, R _cbe respectively output filter equivalent resistance and capacitance with C, definition O point is output Zero potential reference, U _dcfor PWM inverter input voltage;

5), according to PWM modulation principle, get the mean value of one-period, defined variable d _jfor average duty ratio, that is:

$s_j=d_j+\frac{1}{2},j=u,v,w$

6) utilize d _jobtain PWM inverter three-phase output voltage with inversion output loop equation and the Mathematical Modeling of three-phase output current based on average duty ratio is:

$\left[\begin{array}{c}{u}_{\mathrm{ou}}\\ u_{\mathrm{ov}}\\ u_{\mathrm{ow}}\end{array}\right]=(\frac{1}{C}-\frac{R_C}{L}{R}_L)\left[\begin{array}{ccc}1& 0& 0\\ 0& 1& 0\\ 0& 0& 1\end{array}\right]\left[\begin{array}{c}{i}_u\\ i_v\\ i_w\end{array}\right]-\frac{{\mathrm{<figure-callout\; id="1"\; label="R\; C\; L"\; filenames="HDA00003172273700012.png,HDA00003172273700022.png"\; state="\{\{state\}\}">R</figure-callout>}}_C}{L}\left[\begin{array}{ccc}1& 0& 0\\ 0& 1& 0\\ 0& 0& 1\end{array}\right]\left[\begin{array}{c}{u}_{\mathrm{ou}}\\ u_{\mathrm{ov}}\\ u_{\mathrm{ow}}\end{array}\right]+\frac{R_C{\mathrm{<figure-callout\; id="1"\; label="U\; dc\; L"\; filenames="HDA00003172273700012.png,HDA00003172273700022.png"\; state="\{\{state\}\}">U</figure-callout>}}_{\mathrm{dc}}}{L}\left[\begin{array}{ccc}1& 0& 0\\ 0& 1& 0\\ 0& 0& 1\end{array}\right]\left[\begin{array}{c}{d}_u\\ d_v\\ d_w\end{array}\right],$

$\left[\begin{array}{c}{i}_u\\ i_v\\ i_w\end{array}\right]=-\frac{{\mathrm{<figure-callout\; id="1"\; label="R\; L\; L"\; filenames="HDA00003172273700012.png,HDA00003172273700022.png"\; state="\{\{state\}\}">R</figure-callout>}}_L}{L}\left[\begin{array}{ccc}1& 0& 0\\ 0& 1& 0\\ 0& 0& 1\end{array}\right]\left[\begin{array}{c}{i}_u\\ i_v\\ i_w\end{array}\right]-\frac{1}{\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HDA00003172273700012.png,HDA00003172273700022.png"\; state="\{\{state\}\}">L</figure-callout>}}\left[\begin{array}{ccc}1& 0& 0\\ 0& 1& 0\\ 0& 0& 1\end{array}\right]\left[\begin{array}{c}{u}_{\mathrm{ou}}\\ u_{\mathrm{ov}}\\ u_{\mathrm{ow}}\end{array}\right]+\frac{{\mathrm{<figure-callout\; id="1"\; label="U\; dc\; L"\; filenames="HDA00003172273700012.png,HDA00003172273700022.png"\; state="\{\{state\}\}">U</figure-callout>}}_{\mathrm{dc}}}{L}\left[\begin{array}{ccc}1& 0& 0\\ 0& 1& 0\\ 0& 0& 1\end{array}\right]\left[\begin{array}{c}{d}_u\\ d_v\\ d_w\end{array}\right],$

7) by u _ou, u _ov, u _ow, i _u, i _v, i _w, variable d _jthrough transformation matrix T, carry out Clark conversion respectively, obtain voltage u under the static α β of two-phase coordinate system _{o α}, u _{o β}, current i _α, i _β, variable d _α, d _β;

8) Mathematical Modeling described in step 6) is shone upon to Clarke conversion by equivalence, obtains PWM inverter Mathematical Modeling under α β coordinate system and be:

$\left[\begin{array}{c}{u}_{\mathrm{o\&alpha;}}\\ u_{\mathrm{o\&beta;}}\end{array}\right]=\left[\begin{array}{cc}\frac{1}{C}-\frac{R_C}{\mathrm{<figure-callout\; id="0"\; label="L\; R\; L"\; filenames="HDA00003172273700033.png"\; state="\{\{state\}\}">L</figure-callout>}}{R}_L{}_{}& 0\\ 0& \frac{1}{C}-\frac{R_C}{L}{R}_L\end{array}\right]\left[\begin{array}{c}{i}_{\mathrm{\&alpha;}}\\ i_{\mathrm{\&beta;}}\end{array}\right]+\left[\begin{array}{cc}\frac{{\mathrm{<figure-callout\; id="0"\; label="R\; C\; L"\; filenames="HDA00003172273700033.png"\; state="\{\{state\}\}">R</figure-callout>}}_C}{L}& 0\\ 0& \frac{R_C}{L}\end{array}\right]\left[\begin{array}{c}{u}_{\mathrm{o\&alpha;}}\\ u_{\mathrm{o\&beta;}}\end{array}\right]+\left[\begin{array}{cc}\frac{R_C}{L}{u}_{\mathrm{<figure-callout\; id="0"\; label="dc"\; filenames="HDA00003172273700033.png"\; state="\{\{state\}\}">dc</figure-callout>}}& 0\\ 0& \frac{R_C}{L}{u}_{\mathrm{dc}}\end{array}\right]\left[\begin{array}{c}{d}_{\mathrm{\&alpha;}}\\ d_{\mathrm{\&beta;}}\end{array}\right],$

$\left[\begin{array}{c}{i}_{\mathrm{\&alpha;}}\\ i_{\mathrm{\&beta;}}\end{array}\right]=\left[\begin{array}{cc}-\frac{{\mathrm{<figure-callout\; id="0"\; label="R\; L\; L"\; filenames="HDA00003172273700033.png"\; state="\{\{state\}\}">R</figure-callout>}}_L}{L}& 0\\ 0& -\frac{R_L}{L}\end{array}\right]\left[\begin{array}{c}{i}_{\mathrm{\&alpha;}}\\ i_{\mathrm{\&beta;}}\end{array}\right]\begin{array}{}\end{array}+\left[\begin{array}{cc}-\frac{1}{\mathrm{<figure-callout\; id="0"\; label="L"\; filenames="HDA00003172273700033.png"\; state="\{\{state\}\}">L</figure-callout>}}& 0\\ 0& -\frac{1}{L}\end{array}\right]\left[\begin{array}{c}{u}_{\mathrm{o\&alpha;}}\\ u_{\mathrm{o\&beta;}}\end{array}\right]+\left[\begin{array}{cc}\frac{u_{\mathrm{<figure-callout\; id="0"\; label="dc\; L"\; filenames="HDA00003172273700033.png"\; state="\{\{state\}\}">dc</figure-callout>}}}{L}& 0\\ 0& \frac{u_{\mathrm{dc}}}{L}\end{array}\right]\left[\begin{array}{c}{d}_{\mathrm{\&alpha;}}\\ d_{\mathrm{\&beta;}}\end{array}\right];$

9) by above-mentioned steps 8) in PWM inverter Mathematical Modeling parameter under α β coordinate system by equivalent mapping transformation, be decoupled into linear DC amount, processor by control linear DC quantity realize the control to PWM inverter;

10) sampling inversion output transformer outlet side phase current, and calculate nearly n the mean effective value size of described phase current, get predefined current threshold I in maximum mean effective value and processor _sfrelatively, electric current difference is sent in current inner loop pi regulator, electric current difference through pi regulator regulate after as α axle controlled quentity controlled variable, through transformation matrix of coordinates P, be reduced into three phase static coordinate control amount with 0 regulated quantity of β axle, with after through PWM inverter regulation and control, control IGBT gate drive signal, make the phase difference all-the-time stable of inversion output transformer outlet side phase voltage, output current phase is progressively reduced to predefined current threshold in processor.

In described step 7), the expression formula of transformation matrix T is:

The utility model device major function has: during overload, keep voltage in setting range; During load short circuits, disconnect current transformer output voltage protection internal power device, can bear longer fault handling time; During trouble shooting, can recover current transformer work.

The task of switching controls is to judge that current transformer normal running conditions, to Failure elimination, switches back to normal mode of operation.When current transformer is normally worked in voltage constant pattern, once current transformer, occur even short circuit of impact load, first PWM drive circuit works, and Current Limits surely within the specific limits, then in digital control circuit processor, work, judge whether switchback normal mode of operation.

Under nominal situation, the average of three-phase output voltage is near rated value, and the average of three-phase output current is in nominal load current.When current transformer output short-circuit, because current transformer itself has certain internal resistance, and load resistance is minimum during short circuit, and suitable with the internal resistance of current transformer, therefore current transformer output voltage can fall rapidly, electric current is now very large.Now hardware current limliting works, by Current Control within limits, thereby so output voltage because of load resistance very little also very little, almost nil.Once short trouble is eliminated, output current of converter still maintains cut-off current just now, but now load resistance increases, and causes output voltage to increase very soon, and the rising of voltage must exceed the normal output voltage before short trouble.The threshold voltage that current transformer exits current-limiting protection pattern is set; once the maximum of three phase voltage effective values of current transformer output, be greater than the threshold voltage of current-limiting protection pattern; think that fault eliminates; current-limiting protection subprogram exits control; current transformer switches back normal mode of operation, avoids causing vibration.

Compared with prior art, the beneficial effect that the utility model has is: device of the present utility model is compared other frequency converter running protection products, can be in frequency converter running effectively current-limiting protection, can respond fast, can resist instantaneous and non-instantaneous short-circuit impact; This device performance is stable, controls precisely, and coefficient of safety is high, has very strong practicality and extensive market application foreground; Method reliability of the present utility model is high, can effectively guarantee that current transformer maintains current limit output between age at failure, effectively protects current transformer, makes output obtain good voltage current waveform simultaneously, has maintained the continuation of power supply.

Accompanying drawing explanation

Fig. 1 is the utility model one example structure block diagram;

Fig. 2 (a) is the utility model one embodiment inversion output transformer illustraton of model; Fig. 2 (b) is the utility model one embodiment inversion output transformer isoboles;

Fig. 3 is that the utility model one Embodiment C larke conversion three phase static coordinate is to two-phase static coordinate mapping graph;

Fig. 4 is the utility model one embodiment PWM inverter, correction reactor, output transformer and output filter circuit equivalent circuit diagram;

Fig. 5 is the utility model one embodiment α axle equivalence single-phase semi-bridge converter structure block diagram;

Fig. 6 is the utility model one embodiment current sampling circuit schematic diagram;

Fig. 7 is the utility model one embodiment voltage sampling circuit schematic diagram;

Fig. 8 is the utility model one embodiment current transformer output short-circuit hardware lockout current limliting schematic diagram;

Fig. 9 is the utility model one embodiment Current limited Control and normal mode of operation changing method figure;

Figure 10 is the utility model one embodiment current limliting interrupt control method flow chart.

Embodiment

As shown in Figure 1, the utility model one embodiment Main Function device cell in dotted line frame, comprise digital control circuit processor, three voltage signal sampling circuit, three current signal sample circuits, PWM inverter, proofread and correct reactor, inversion output transformer and current transformer output filter circuit, described current transformer output filter circuit passes through voltage sampling circuit, the voltage and current signal input digital control circuit processor of current sampling circuit sampling current transformer PWM inverter output, described digital control circuit processor is connected with PWM inverter by PWM drive circuit, PWM inverter in described current transformer, proofread and correct reactor, inversion output transformer, current transformer output filter circuit connects successively.

The clock frequency that described digital control circuit processor adopting TI company produces reaches the TMS320F28335DSP control chip of 150MHz, is aided with each sample circuit, drive circuit and protective circuit etc.By the decoupling zero to current transformer Mathematical Modeling, can control separately corresponding parameter under α β coordinate system, then control parameter through the corresponding PWM of coordinate inversion, by current/voltage collection signal feedback fault type, switch current transformer operational mode.

Fig. 2 (a), Fig. 2 (b) are illustraton of model and the model isoboles of inversion output transformer, use the transformer of star-like connection, and customization voltage change ratio is 1.

Fig. 3 is that Clarke conversion three phase static coordinate arrives two-phase static coordinate mapping graph, by Tu Ke get, by static three phase coordinate systems, to the expression formula of the constant power conversion transformation matrix T of static two phase coordinate systems, is:

By static two phase coordinate systems to the transformation matrix of static three phase coordinate systems be transformation matrix T inverse matrix, definition P=T ^-1, P expression formula is:

Fig. 4 is PWM inverter, correction reactor, output transformer and output filter circuit equivalent circuit diagram.For convenient design control system, can be by coordinate transform, by three-phase symmetrical coordinate system (a, b, c) transform to two-phase rest frame (α, β), after this conversion, the sinusoidal quantity of three-phase alternation has changed into DC quantity, simplified control system design greatly.

In current transformer, PWM inverter input terminal is equivalent to a DC current source, and definition input voltage size is U _dc, input current size is I _dc, definition s _k=1(k=u, v, w) be IGBT conducting on the corresponding circuitry phase arm of PWM inverter bridge, lower IGBT turn-offs, s _k=0(k=u, v, w) be IGBT conducting under the corresponding circuitry phase arm of PWM inverter bridge, upper IGBT turn-offs, u, v, w is three brachium pontis of corresponding PWM inverter respectively; According to KCL and KVL law, obtain the inversion output loop equation under three phase static coordinate system that PWM inverter three-phase output voltage and electric current are corresponding:

$\left[\begin{array}{c}{u}_{\mathrm{ou}}\\ u_{\mathrm{ov}}\\ u_{\mathrm{ow}}\end{array}\right]=(\frac{1}{C}-\frac{R_C}{L}{R}_L)\left[\begin{array}{ccc}1& 0& 0\\ 0& 1& 0\\ 0& 0& 1\end{array}\right]\left[\begin{array}{c}{i}_u\\ i_v\\ i_w\end{array}\right]-\frac{{\mathrm{<figure-callout\; id="1"\; label="R\; C\; L"\; filenames="HDA00003172273700012.png,HDA00003172273700022.png"\; state="\{\{state\}\}">R</figure-callout>}}_C}{L}\left[\begin{array}{ccc}1& 0& 0\\ 0& 1& 0\\ 0& 0& 1\end{array}\right]\left[\begin{array}{c}{u}_{\mathrm{ou}}\\ u_{\mathrm{ov}}\\ u_{\mathrm{ow}}\end{array}\right]+\frac{R_C{U}_{\mathrm{dc}}}{L}\left[\begin{array}{ccc}\frac{2}{3}& -\frac{1}{3}& \frac{2}{3}\\ -\frac{1}{3}& \frac{2}{3}& \frac{2}{3}\\ -\frac{1}{3}& -\frac{1}{3}& \frac{2}{3}\end{array}\right]\left[\begin{array}{c}{s}_u\\ s_v\\ s_w\end{array}\right]$

$\left[\begin{array}{c}{i}_u\\ i_v\\ i_w\end{array}\right]=-\frac{{\mathrm{<figure-callout\; id="1"\; label="R\; L\; L"\; filenames="HDA00003172273700012.png,HDA00003172273700022.png"\; state="\{\{state\}\}">R</figure-callout>}}_L}{L}\left[\begin{array}{ccc}1& 0& 0\\ 0& 1& 0\\ 0& 0& 1\end{array}\right]\left[\begin{array}{c}{i}_u\\ i_v\\ i_w\end{array}\right]-\frac{1}{\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HDA00003172273700012.png,HDA00003172273700022.png"\; state="\{\{state\}\}">L</figure-callout>}}\left[\begin{array}{ccc}1& 0& 0\\ 0& 1& 0\\ 0& 0& 1\end{array}\right]\left[\begin{array}{c}{u}_{\mathrm{ou}}\\ u_{\mathrm{ov}}\\ u_{\mathrm{ow}}\end{array}\right]+\frac{U_{\mathrm{dc}}}{L}\left[\begin{array}{ccc}\frac{2}{3}& -\frac{1}{3}& \frac{2}{3}\\ -\frac{1}{3}& \frac{2}{3}& \frac{2}{3}\\ -\frac{1}{3}& -\frac{1}{3}& \frac{2}{3}\end{array}\right]\left[\begin{array}{c}{s}_u\\ s_v\\ s_w\end{array}\right]$

Wherein, u _ou, u _ov, u _owbe respectively the output phase voltage of current transformer output filter circuit end, i _u, i _v, i _wbe respectively PWM inverter output current phase, proofread and correct reactor consistent with inversion output transformer equivalent resistance inductance resistance sizes, size is used respectively L and R _lrepresent, current transformer output filter circuit equivalent resistance and capacitance are respectively R _cand C, definition O point is output Zero potential reference.

According to PWM modulation principle, for switch function variable in formula, can get the mean value of one-period, defined variable d _j(j=u, v, w) is average duty ratio, that is:

$s_j=d_j+\frac{1}{2},j=u,v,w$

By d _jbring inversion output loop equation into and obtain output voltage, output current based on average duty ratio function Mathematical Modeling is:

$\left[\begin{array}{c}{u}_{\mathrm{ou}}\\ u_{\mathrm{ov}}\\ u_{\mathrm{ow}}\end{array}\right]=(\frac{1}{C}-\frac{R_C}{L}{R}_L)\left[\begin{array}{ccc}1& 0& 0\\ 0& 1& 0\\ 0& 0& 1\end{array}\right]\left[\begin{array}{c}{i}_u\\ i_v\\ i_w\end{array}\right]-\frac{{\mathrm{<figure-callout\; id="1"\; label="R\; C\; L"\; filenames="HDA00003172273700012.png,HDA00003172273700022.png"\; state="\{\{state\}\}">R</figure-callout>}}_C}{L}\left[\begin{array}{ccc}1& 0& 0\\ 0& 1& 0\\ 0& 0& 1\end{array}\right]\left[\begin{array}{c}{u}_{\mathrm{ou}}\\ u_{\mathrm{ov}}\\ u_{\mathrm{ow}}\end{array}\right]+\frac{R_C{\mathrm{<figure-callout\; id="1"\; label="U\; dc\; L"\; filenames="HDA00003172273700012.png,HDA00003172273700022.png"\; state="\{\{state\}\}">U</figure-callout>}}_{\mathrm{dc}}}{L}\left[\begin{array}{ccc}1& 0& 0\\ 0& 1& 0\\ 0& 0& 1\end{array}\right]\left[\begin{array}{c}{d}_u\\ d_v\\ d_w\end{array}\right]$

$\left[\begin{array}{c}{i}_u\\ i_v\\ i_w\end{array}\right]=-\frac{{\mathrm{<figure-callout\; id="1"\; label="R\; L\; L"\; filenames="HDA00003172273700012.png,HDA00003172273700022.png"\; state="\{\{state\}\}">R</figure-callout>}}_L}{L}\left[\begin{array}{ccc}1& 0& 0\\ 0& 1& 0\\ 0& 0& 1\end{array}\right]\left[\begin{array}{c}{i}_u\\ i_v\\ i_w\end{array}\right]-\frac{1}{\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HDA00003172273700012.png,HDA00003172273700022.png"\; state="\{\{state\}\}">L</figure-callout>}}\left[\begin{array}{ccc}1& 0& 0\\ 0& 1& 0\\ 0& 0& 1\end{array}\right]\left[\begin{array}{c}{u}_{\mathrm{ou}}\\ u_{\mathrm{ov}}\\ u_{\mathrm{ow}}\end{array}\right]+\frac{{\mathrm{<figure-callout\; id="1"\; label="U\; dc\; L"\; filenames="HDA00003172273700012.png,HDA00003172273700022.png"\; state="\{\{state\}\}">U</figure-callout>}}_{\mathrm{dc}}}{L}\left[\begin{array}{ccc}1& 0& 0\\ 0& 1& 0\\ 0& 0& 1\end{array}\right]\left[\begin{array}{c}{d}_u\\ d_v\\ d_w\end{array}\right]$

To export phase voltage u _ou, u _ov, u _ow, output current phase i _u, i _v, i _w, variable d _j(j=u, v, w) carries out Clark conversion through transformation matrix T respectively, obtains voltage u under the static α β of two-phase coordinate system _{o α}, u _{o β}, current i _α, i _β, variable d _α, d _β.

Based on average duty ratio function Mathematical Modeling, by equivalence, shine upon Clarke conversion, obtain PWM inverter Mathematical Modeling under α β coordinate system and be:

$\left[\begin{array}{c}{u}_{\mathrm{o\&alpha;}}\\ u_{\mathrm{o\&beta;}}\end{array}\right]=\left[\begin{array}{cc}\frac{1}{C}-\frac{R_C}{\mathrm{<figure-callout\; id="0"\; label="L\; R\; L"\; filenames="HDA00003172273700033.png"\; state="\{\{state\}\}">L</figure-callout>}}{R}_L{}_{}& 0\\ 0& \frac{1}{C}-\frac{R_C}{L}{R}_L\end{array}\right]\left[\begin{array}{c}{i}_{\mathrm{\&alpha;}}\\ i_{\mathrm{\&beta;}}\end{array}\right]+\left[\begin{array}{cc}\frac{{\mathrm{<figure-callout\; id="0"\; label="R\; C\; L"\; filenames="HDA00003172273700033.png"\; state="\{\{state\}\}">R</figure-callout>}}_C}{L}& 0\\ 0& \frac{R_C}{L}\end{array}\right]\left[\begin{array}{c}{u}_{\mathrm{o\&alpha;}}\\ u_{\mathrm{o\&beta;}}\end{array}\right]+\left[\begin{array}{cc}\frac{R_C}{L}{u}_{\mathrm{<figure-callout\; id="0"\; label="dc"\; filenames="HDA00003172273700033.png"\; state="\{\{state\}\}">dc</figure-callout>}}& 0\\ 0& \frac{R_C}{L}{u}_{\mathrm{dc}}\end{array}\right]\left[\begin{array}{c}{d}_{\mathrm{\&alpha;}}\\ d_{\mathrm{\&beta;}}\end{array}\right]$

$\left[\begin{array}{c}{i}_{\mathrm{\&alpha;}}\\ i_{\mathrm{\&beta;}}\end{array}\right]=\left[\begin{array}{cc}-\frac{{\mathrm{<figure-callout\; id="0"\; label="R\; L\; L"\; filenames="HDA00003172273700033.png"\; state="\{\{state\}\}">R</figure-callout>}}_L}{L}& 0\\ 0& -\frac{R_L}{L}\end{array}\right]\left[\begin{array}{c}{i}_{\mathrm{\&alpha;}}\\ i_{\mathrm{\&beta;}}\end{array}\right]\begin{array}{}\end{array}+\left[\begin{array}{cc}-\frac{1}{\mathrm{<figure-callout\; id="0"\; label="L"\; filenames="HDA00003172273700033.png"\; state="\{\{state\}\}">L</figure-callout>}}& 0\\ 0& -\frac{1}{L}\end{array}\right]\left[\begin{array}{c}{u}_{\mathrm{o\&alpha;}}\\ u_{\mathrm{o\&beta;}}\end{array}\right]+\left[\begin{array}{cc}\frac{u_{\mathrm{<figure-callout\; id="0"\; label="dc\; L"\; filenames="HDA00003172273700033.png"\; state="\{\{state\}\}">dc</figure-callout>}}}{L}& 0\\ 0& \frac{u_{\mathrm{dc}}}{L}\end{array}\right]\left[\begin{array}{c}{d}_{\mathrm{\&alpha;}}\\ d_{\mathrm{\&beta;}}\end{array}\right]$

Fig. 5 is α axle equivalence single phase half bridge inverter structured flowchart.Mathematical Modeling parameter is by equivalent mapping transformation, three phase static coordinate system alternation coupling paameter can further be decoupled into linear DC amount, β axle should adopt same α axis controller, can be by α axle and β axle DC quantity are controlled respectively to the control realizing PWM inverter.

Fig. 6 is current sampling circuit schematic diagram in AC signal sample circuit, current signal acquisition applications Hall current sensor LA58-P, wherein CUR_U+ and CUR_U-are that current transformer is exported through LA58-P signals collecting, by the output setting of R1 and R2, are delivered to digital control circuit processor data sample port.The first half is current acquisition, and BD3 is rectifier bridge, and alternating current is direct current through over commutation, and Jump is wire jumper, leads to 1 when electric current is excessive, becomes overcurrent protection signal.The latter half is level shifting circuit, for the voltage conforms DSP standard that makes the ID conversion mouthful of exporting DSP.

Fig. 7 is voltage sampling circuit schematic diagram in AC signal sample circuit, and wherein INV_U is current transformer output U phase phase voltage collection signal, and INV_N is the interchange centerline collection signal of current transformer inversion unit output, by change-over circuit, by VINV_U, inputs DSP.T4 is the fertile hereby active low-pass filter of second order Bart, because the FilterLab software adopting is transformed into Liao Yi road unipolarity voltage acquisition signal to design of filter by current transformer AC voltage sampling signal.The unipolarity voltage acquisition signal of filter output is delivered to the AD thief hatch of DSP28335 through level conversion safety circuit after by voltage follower.

Fig. 8 is current transformer output short-circuit hardware lockout current limliting schematic diagram, current signal acquisition applications Hall current sensor LA58-P, wherein CUR_U+ and CUR_U-are current transformer through the output of LA58-P signals collecting, SC and for hardware protection circuit output logic signal, #INV and RESET are respectively logic negate and reset signal output.Current transformer output AC electric current transfers voltage signal to after BD1 rectifier circuit, comparator compares the outlet side maximum phase current through over commutation and hardware current limliting IGBT blockade threshold values, when being greater than blockade threshold values through the outlet side maximum phase current of over commutation, utilize the digital circuit logic of d type flip flop, IGBT gate drive signal is turn-offed, make IGBT be operated in afterflow pattern, and force electric current to decline, when direct current is reduced to set point lower limit, driving pulse works again, and current transformer recovers normal work.If now fault is not eliminated and Current limited Control interrupt routine does not work, PWM drive circuit starts again action, so repeatedly, Current Limits is fixed on below set point, plays the effect of protection current transformer.D type flip flop simultaneously output signal is delivered to DSP main control chip request startup current limliting interrupt routine.

Fig. 9 is Current limited Control and normal mode of operation changing method figure.During K=1, current transformer mode controller effect working properly, PWM inverter output constant voltage signal.During K=0, PWM inverter is operated in current limliting and interrupts control model, and sampling current transformer outlet side phase current also calculates nearly n mean effective value size, gets maximum mean effective value and software current-limiting protection program control threshold values I _sfrelatively, difference is sent in current inner loop pi regulator.Electric current difference through program regulate after as α axle controlled quentity controlled variable, through transformation matrix of coordinates P, be reduced into three phase static coordinate control amount with 0 regulated quantity of β axle, with after through PWM regulation and control, control IGBT gate drive signal, the phase difference all-the-time stable that makes current transformer outlet side phase voltage, output current phase is progressively reduced to program control threshold values.

Figure 10 is the utility model one embodiment current limliting interrupt control method flow chart.Processor response hardware lockout circuit interrupt requests, calculate phase current mean effective value one by one with software current-limiting protection program control threshold values I _sfrelatively, diverter switch K=LT_FLAG in Figure 10, U _sffor current transformer exits the threshold voltage of current-limiting protection pattern, U _mfor the maximum of three phase voltage mean effective values of current transformer output, by several step failure judgement, whether eliminate, to determine to exit, interrupt or operation current-limiting protection adjusting program.

Claims (2)

1. a current transformer current-limiting protection system control device, comprise the AC reactor, electronic switch, PWM rectifier, direct current reactor, the DC filter that connect successively, it is characterized in that, described DC filter is connected with output filter by PWM inverter, correction reactor, inversion output transformer successively; Described output filter is by the first AC signal sample circuit access processor, and described processor is connected with described electronic switch, PWM rectifier, PWM inverter; Described processor connects direct current signal sample circuit output, the second AC signal sample circuit output, between described direct current signal sample circuit input access in parallel DC filter and PWM inverter, between described the second AC signal sample circuit input described AC reactor of access in parallel and electronic switch; Described processor is also connected with current transformer output short-circuit hardware lockout current-limiting circuit, and described current transformer output short-circuit hardware lockout current-limiting circuit comprises the rectifier bridge, comparator, the d type flip flop that connect successively, and described d type flip flop outputs signal to described processor.

2. current transformer current-limiting protection system control device according to claim 1, is characterized in that, the DSP control chip that described processor adopting model is TMS320F28335.

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