CN101026305A - Control device for boost three-phase grid-connected inverting system - Google Patents

Abstract

The disclosed control device is contravariant control device connected to power net in high efficiency by using digital signal processor. Through a stage of step up transform, the control device and control method can feed DC voltage obtained from light-voltage battery array, fuel batteries, wind electric power generation, or other methods to power net. When inputted DC voltage is lower than peak voltage of power net, the invention can generate electricity connected to power net. Features are: simple structure, low cost, miniaturization, reduced power loss in energy transform procedure, and raised system efficiency.

Description

The control device of boost three-phase grid-connected inverting system and control method thereof

Technical field

The present invention relates to a kind of control device and control method thereof of boost three-phase grid-connected inverting system.

Background technology

The direct voltage that is obtained by photovoltaic battery array, fuel cell, wind power generation or other the whole bag of tricks is usually less than the electrical network crest voltage, generally direct voltage need be boosted to can realize that voltage-type generates electricity by way of merging two or more grid systems after being higher than the electrical network crest voltage.Usually the method that adopts has: the single-stage buck type generates electricity by way of merging two or more grid systems, to organize generator unit series connection back is connected to the grid by inverter more, this method system topological is simple, the one-level energy conversion just can realize generating electricity by way of merging two or more grid systems, but when output dc voltage is lower than the electrical network crest voltage, inverter can not carry out operate as normal, reduces system's generating efficiency; Two Stages is generated electricity by way of merging two or more grid systems, prime DC/DC converter is realized boost function, back level DC/AC inverter is realized generating electricity by way of merging two or more grid systems, though the method can be under lower VD normal power generation, but exist circuit structure complicated, used power device is more, and cost is higher relatively, the shortcoming that circuit efficiency is also relatively low; The transformer booster type generates electricity by way of merging two or more grid systems, with combining inverter through the transformer back feed of realizing being incorporated into the power networks that boosts because general mains frequency lower (50Hz), shortcoming such as so exist volume of transformer big, consumptive material is many, and loss is big.Fig. 2 is a conventional buck combining inverter schematic diagram; Fig. 3 is traditional Two Stages combining inverter schematic diagram; Fig. 4 is a traditional transformer booster type combining inverter schematic diagram.

Summary of the invention

The object of the present invention is to provide a kind of boost three-phase grid-connected inverter controlling apparatus and control method thereof, adopt this control device and control method thereof can realize direct voltage by one-level energy conversion feed-in electrical network, and this inverter has boost function, promptly realizes generating electricity by way of merging two or more grid systems under input direct voltage is lower than the situation of electrical network crest voltage.It is simple that this control device and control method thereof have system configuration, and cost is low, but the implement device miniaturization reduces power loss in the energy conversion process simultaneously, improves system effectiveness.

For achieving the above object, the present invention adopts following technical proposals:

A kind of control device of boost three-phase grid-connected inverting system, comprise a digital signal processor, by the electric current supplied with digital signal processor that flows through DC filter in the current sensor senses main circuit, line voltage zero-crossing detector of R phase voltage input of a voltage sensor senses three phase network, described line voltage zero-crossing detector carries out supplied with digital signal processor after the signal processing with the R phase voltage of input, digital signal processor carries out pulse-width modulation and interval calculating back output two pulse signals and a switching tube selection of one road wayside signaling input circuit according to the current signal and the voltage zero-crossing signal of input, described switching tube selects circuit according to the wayside signaling of input the pulse signal of importing to be carried out exporting six tunnel drive signals behind the signal condition, and switching tube selects drive circuit of drive signal input of circuit output to isolate and power amplification rear drive main circuit.

In the control device of above-mentioned boost three-phase grid-connected inverting system, described switching tube selects circuit to select 1 device 74HC151 or 74HC251 or 74HC354 or other identical function device to form by 3 address latch 74HC164 and 68, the two-way pulse width signal S that will be imported by digital signal processor _aAnd S _bSeparately negate and with after obtain another road pulse width signal S _c, 8 select the wayside signaling S of 1 circuit according to input _eWith 3 road pulse width signal S _a, S _b, S _cConditioning generates 6 tunnel drive signals and outputs to drive circuit.

In the control device of above-mentioned boost three-phase grid-connected inverting system, described drive circuit adopts the EXB841 of FUJI ELECTRIC or HR065 or the M57962L of Mitsubishi or PC923 or the HCPL-3120 of Agilent or the IR2110 or the IR2130 drive circuit of HCPL-316J or American I R company of Sharp that Japanese English reaches.

A kind of control method that is used for boost three-phase grid-connected inversion control device is characterized in that controlled step is as follows:

1. with the current i of current sensor senses _LVoltage zero-crossing signal with the generation of line voltage zero-crossing detector

U _RBe input to digital signal processor;

2. digital signal processor (3) calculates the grid-connected current coefficient according to grid-connected current $k=$ $\frac{2\sqrt{2}{\mathrm{<figure-callout\; id="3"\; label="V\; g"\; filenames="A20071003741200121.png,A20071003741200131.png"\; state="\{\{state\}\}">V</figure-callout>}}_g}{3{\mathrm{Ui}}_L^{*}}$ $;$

3. k and i _LMultiply each other, product is sent into temporary register T _Temp

4. according to voltage zero-crossing signal U _RCalculate current operation angle θ and wayside signaling S _e

5. look into modulation signal figure according to current operation angle θ and obtain sine wave signal M _a, M _b

6. T _TempAnd M _aMultiply each other, product is sent into comparand register 1; T _TempAnd M _bMultiply each other, 1 deducts the difference that product obtains sends into comparand register 2;

7. the inner comparand register of digital signal processor (3) relatively generates pulse width signal S _a, S _bOutput to switching tube and select circuit; With wayside signaling S _eOutput to switching tube and select circuit.

The present invention compared with prior art, have following conspicuous outstanding substantive distinguishing features and remarkable advantage: the present invention be a kind of be the high efficiency parallel network reverse control device of core with digital signal processor (DSP), the direct voltage that it can obtain photovoltaic battery array, fuel cell, wind power generation or other the whole bag of tricks is by feed-in electrical network after the first class boost conversion, can realize generating electricity by way of merging two or more grid systems under input direct voltage is lower than the situation of electrical network crest voltage.The present invention is simple in structure, cost is low, but the implement device miniaturization reduces power loss in the energy conversion process, improves system effectiveness.

Description of drawings

Fig. 1 is a boost three-phase grid-connected inverter controlling apparatus structured flowchart of the present invention.

Fig. 2 is a conventional buck combining inverter schematic diagram.

Fig. 3 is traditional Two Stages combining inverter schematic diagram.

Fig. 4 is a traditional transformer booster type combining inverter schematic diagram.

Fig. 5 is the section definition schematic diagram.

Fig. 6 is a PWM pulse-width modulation schematic diagram.

Fig. 7 is a main circuit different operating view.

Fig. 8 is based on digital signal processor PWM pulse-width modulation schematic diagram.

Fig. 9 is the control algolithm flow chart.

Figure 10 is modulation signal figure.

Figure 11 is that driving pulse generates schematic diagram.

Figure 12 is that switching tube is selected circuit diagram.

Embodiment

Details are as follows in conjunction with the accompanying drawings for the preferred embodiments of the present invention:

Referring to Fig. 1, the control device of this boost three-phase grid-connected inverting system, comprise a digital signal processor 3, detect the electric current supplied with digital signal processor 3 that flows through DC filter in the main circuit by a current sensor 5, a voltage sensor 1 detects line voltage zero-crossing detector 2 of R phase voltage input of three phase network, described line voltage zero-crossing detector 2 carries out supplied with digital signal processor 3 after the signal processing with the R phase voltage of input, digital signal processor 3 carries out pulse-width modulation and interval calculating back output two pulse signals and a switching tube selection of one road wayside signaling input circuit 4 according to the current signal and the voltage zero-crossing signal of input, described switching tube selects circuit 4 according to the wayside signaling of input the pulse signal of importing to be carried out exporting six tunnel drive signals behind the signal condition, and switching tube selects drive circuit 6 of drive signal input of circuit 4 outputs to isolate and power amplification rear drive main circuit 7.

Referring to Figure 12, in the control device of above-mentioned boost three-phase grid-connected inverting system, described switching tube selects circuit 4 to select 1 device 74HC151 or 74HC251 or 74HC354 or other identical function device to form by 3 address latch 74HC164 and 68, the two-way pulse width signal S that will be imported by digital signal processor 3 _aAnd S _bSeparately negate and with after obtain another road pulse width signal S _c, 8 select the wayside signaling S of 1 circuit according to input _eWith 3 road pulse width signal S _a, S _b, S _cConditioning generates 6 tunnel drive signals and outputs to drive circuit.

In the control device of above-mentioned boost three-phase grid-connected inverting system, described drive circuit 6 adopts the EXB841 of FUJI ELECTRIC or HR065 or the M57962L of Mitsubishi or PC923 or the HCPL-3120 of Agilent or the IR2110 or the IR2130 drive circuit of HCPL-316J or American I R company of Sharp that Japanese English reaches.

A kind of control method that is used for boost three-phase grid-connected inversion control device is characterized in that controlled step is as follows:

1. the current i that current sensor 1 is detected _LVoltage zero-crossing signal U with 2 generations of line voltage zero-crossing detector _RBe input to digital signal processor 3;

2. digital signal processor 3 calculates the grid-connected current coefficient according to grid-connected current $k=\frac{2\sqrt{2}{\mathrm{<figure-callout\; id="3"\; label="V\; g"\; filenames="A20071003741200121.png,A20071003741200131.png"\; state="\{\{state\}\}">V</figure-callout>}}_g}{3{\mathrm{Ui}}_L^{*}};$

3. k and i _LMultiply each other, product is sent into temporary register T _Temp

4. according to voltage zero-crossing signal U _RCalculate current operation angle θ and wayside signaling S _e

5. look into modulation signal figure according to current operation angle θ and obtain sine wave signal M _a, M _b

6. T _TempAnd M _aMultiply each other, product is sent into comparand register 1; T _TempAnd M _bMultiply each other, 1 deducts the difference that product obtains sends into comparand register 2;

7. digital signal processor 3 inner comparand registers relatively generate pulse width signal S _a, S _bOutput to switching tube and select circuit; With wayside signaling S _eOutput to switching tube and select circuit.

The control method and the principle of this boost three-phase grid-connected inverter are summarized as follows:

Figure 1 shows that boost three-phase grid-connected inverter controlling apparatus.The R phase voltage signal u that sampling obtains according to voltage sensor _REach cycle of electrical network is divided into 6 intervals, as shown in Figure 5.To be the control method that example specifies boost three-phase grid-connected inverter with interval I below.

When interval I, switching tube S _SNConducting, switching tube S _RN, S _TNTurn-off (consulting Fig. 7), top three switching tubes of three-phase brachium pontis carry out PWM modulation (conducting in turn), and concrete drive signal as shown in Figure 6.

Among Fig. 6, ki _LU _R, ki _LU _TBe respectively and line voltage e _R, e _TThe modulation signal of homophase, i _LFor flowing through the electric current of inductance L, k is the current sample amplification coefficient, T _SBe carrier cycle.When carrier cycle is higher, make the following assumptions:

1. U in each carrier cycle _R, U _TIt is a constant;

2. i _LRipple is little, is a constant in each carrier cycle.

Ki among the figure _LU _RModulation signal and in the preceding half period sawtooth carrier wave ratio generate drive signal, wherein T _aPulsed drive S _SP, T _a' pulsed drive S _RP

Ki _LU _TThe interim sawtooth carrier wave ratio of modulation signal and second half generates drive signal, wherein T _bPulsed drive S _SP, T _b' pulsed drive S _TP

Main circuit has four kinds of states (as shown in Figure 8) in each carrier cycle:

State 1: switching tube S _SPConducting, voltage source V _gThrough inductance L, switching tube S _SP, S _SNForm the loop, inductive current i _LWith speed V _g/ L is linear to rise filter capacitor C _R, C _S, C _TKeep grid-connected current i _R, i _S, i _TThis state inductance L storage power.

State 2: switching tube S _SPShutoff, S _RPConducting, voltage source V _gThrough inductance L, switching tube S _RPFlow into R ' end, again by the outflow of S ' end, through switching tube S _SNForm the loop, at this moment e _RS＞V _g(these topological characteristics are exactly that line voltage compares V _gThe feed that can be incorporated into the power networks under the high state is so there is this relation), so current i _LWith speed (e _RS-V _g)/L is linear to descend filter capacitor C _TKeep grid-connected current i _TUnder this state, power supply V _gSimultaneously present energy with inductance L to electrical network.

State 3: with above-mentioned state 1.

State 4: switching tube S _SPShutoff, S _TPConducting, voltage source V _gThrough inductance L, switching tube S _TPFlow into T ' end, again by the outflow of S ' end, through switching tube S _SNForm the loop, at this moment e _TS＞V _gSo, current i _LWith speed (e _TS-V _g)/L is linear to descend filter capacitor C _RKeep grid-connected current i _RThis state power supply V _gSimultaneously present energy with inductance L to electrical network.

Similar according to Fig. 6 intermediate cam shape, can obtain:

$\left\{\begin{array}{c}{T}_a=(T_S/2)(1-{\mathrm{ki}}_L{U}_R)\\ T_b=(T_S/2)(1-{\mathrm{ki}}_L{U}_T)\end{array}\right.---\left(1\right)$

Inductive current i in carrier cycle among Fig. 6 _LBe changed to:

$I_{\mathrm{Lt}}-{\mathrm{<figure-callout\; id="0"\; label="I\; L"\; filenames="A20071003741200151.png,A20071003741200171.png"\; state="\{\{state\}\}">I</figure-callout>}}_L=\frac{V_g}{L}\&CenterDot;T_a+\frac{V_g-e_{\mathrm{RS}}}{L}\&CenterDot;T_a^{\&prime;}+\frac{V_g}{L}\&CenterDot;T_b+\frac{V_g-e_{\mathrm{TS}}}{L}\&CenterDot;T_b^{\&prime;}$

$=\frac{V_g}{L}\&CenterDot;T_a+\frac{V_g-e_{\mathrm{RS}}}{L}\&CenterDot;(\frac{T_S}{2}-T_a)+\frac{V_g}{L}\&CenterDot;T_b+\frac{V_g-e_{\mathrm{TS}}}{L}\&CenterDot;(\frac{T_S}{2}-T_b)---\left(2\right)$

Formula (1) substitution formula (2) is got:

$I_{\mathrm{Lt}}-{\mathrm{<figure-callout\; id="0"\; label="I\; L"\; filenames="A20071003741200151.png,A20071003741200171.png"\; state="\{\{state\}\}">I</figure-callout>}}_L=\frac{V_g}{L}\&CenterDot;T_s-\frac{{\mathrm{ki}}_L}{L}\&CenterDot;\frac{T_S}{2}(U_R\&CenterDot;e_{\mathrm{RS}}+U_T\&CenterDot;e_{\mathrm{TS}})---\left(3\right)$

If line voltage is (consulting Fig. 5):

$\left\{\begin{array}{c}{e}_R=\sqrt{2}U\sin \mathrm{\&omega;t}\\ e_S=\sqrt{2}U\sin (\mathrm{\&omega;t}-\frac{2}{3}\mathrm{\&pi;})\\ e_T=\sqrt{2}U\sin (\mathrm{\&omega;t}+\frac{2}{3}\mathrm{\&pi;})\end{array}\right.---\left(4\right)$

Since in this control mode, modulation signal U _R, U _S, U _TWith line voltage e _R, e _S, e _TSame-phase, that is:

$\left\{\begin{array}{c}{U}_R=\sin \mathrm{\&omega;t}\\ U_S=\sin (\mathrm{\&omega;t}-\frac{2}{3}\mathrm{\&pi;})\\ U_T=\sin (\mathrm{\&omega;t}+\frac{2}{3}\mathrm{\&pi;})\end{array}\right.---\left(5\right)$

Can try to achieve by formula (4), (5):

$\left\{\begin{array}{c}{U}_R\&CenterDot;e_{\mathrm{RS}}=\sqrt{\frac{3}{2}}U[\sin (2\mathrm{\&omega;t}-\frac{\mathrm{\&pi;}}{3})+\frac{\sqrt{3}}{2}]\\ U_T\&CenterDot;e_{\mathrm{TS}}=\sqrt{\frac{3}{2}}U[\sin (2\mathrm{\&omega;t}+\frac{2\mathrm{\&pi;}}{3})+\frac{\sqrt{3}}{2}]\end{array}\right.---\left(6\right)$

Formula (6) substitution formula (3):

$I_{\mathrm{Lt}}-{\mathrm{<figure-callout\; id="0"\; label="I\; L"\; filenames="A20071003741200151.png,A20071003741200171.png"\; state="\{\{state\}\}">I</figure-callout>}}_L=\frac{V_g}{L}\&CenterDot;T_s-\frac{{\mathrm{ki}}_{L}U}{L}\&CenterDot;\frac{3\sqrt{2}}{4}{T}_S---\left(7\right)$

Under the stable situation, I _Lt-I _L0=0, substitution formula (7):

$i_L=\frac{2\sqrt{2}}{3}\&CenterDot;\frac{V_g}{\mathrm{kU}}---\left(8\right)$

Work as S _RPDuring conducting, with power supply V _gMiddle energy feed-in R phase electrical network, S _RPON time is T _a', low-pass filtering electric capacity is at S _RPConduction period storage power, all the other times are kept grid-connected current i _RSo i _RBe current i _LConducting T _aThe mean value of ' time:

$i_R=i_L\&CenterDot;\frac{T_a^{\&prime;}}{T_S}=i_L\&CenterDot;\frac{\frac{T_S}{2}-T_a}{T_S}=\frac{k{U}_{\mathrm{<figure-callout\; id="2"\; label="R\; i\; L"\; filenames="A20071003741200121.png,A20071003741200131.png"\; state="\{\{state\}\}">R</figure-callout>}}{i}_L^{}{}_2^{}}{2}=\frac{4{\mathrm{<figure-callout\; id="2"\; label="V\; g"\; filenames="A20071003741200121.png,A20071003741200131.png"\; state="\{\{state\}\}">V</figure-callout>}}_g^{}}{9\mathrm{<figure-callout\; id="2"\; label="k\; U"\; filenames="A20071003741200121.png,A20071003741200131.png"\; state="\{\{state\}\}">k</figure-callout>}{U}^{}{}^2}\&CenterDot;U_R---\left(9\right)$

From formula (9) as can be seen.Current i _RWith electrical network electromotive force e _RSame-phase, promptly grid-connected current is and the synchronous sine wave of line voltage.

Figure 8 shows that the pulsewidth that realizes based on digital signal processor generates schematic diagram.Comparison diagram 6 and Fig. 8 are not difficult to find, realize for the ease of digital signal processor, and two sawtooth carrier waves among Fig. 6 are merged into a sawtooth carrier wave, simultaneously modulation signal ki _LU _TBe adjusted into (1-ki accordingly _LU _T).After adopting the method, though the switching tube conducting is different from Fig. 6 in proper order in a carrier cycle, this algorithm does not change same switch pipe driving pulse width, does not therefore influence final grid-connected current.Adopt identical control method that rest interval is controlled, as shown in table 1.When interval I, III, V, a switching tube conducting in three following brachium pontis, two switching tubes are closed in addition, go up brachium pontis for three and carry out PWM modulation in turn; When interval II, IV, VI, three switching tube conductings of going up in the brachium pontis, two switching tubes are closed in addition, and three following brachium pontis carry out PWM modulation in turn.After above-mentioned control method, can realize that finally net side sinusoidal current is incorporated into the power networks.

The The whole control algorithm of the boost three-phase grid-connected inverter of realizing based on digital signal processor as shown in Figure 9.After digital signal processor powers on, at first carry out parameter initialization, inquire about the instruction of being incorporated into the power networks then, in case receive the instruction of being incorporated into the power networks, digital signal processor carries out pulsewidth and calculates.Concrete steps are as follows:

1. with the current i of current sensor senses _LVoltage zero-crossing signal U with the generation of line voltage zero-crossing detector _RBe input to digital signal processor;

2. digital signal processor calculates the grid-connected current coefficient according to grid-connected current $k=\frac{2\sqrt{2}{\mathrm{<figure-callout\; id="3"\; label="V\; g"\; filenames="A20071003741200121.png,A20071003741200131.png"\; state="\{\{state\}\}">V</figure-callout>}}_g}{3{\mathrm{Ui}}_L^{*}};$

3. k and i _LMultiply each other, product is sent into temporary register T _Temp

4. according to voltage zero-crossing signal U _RCalculate current operation angle θ and wayside signaling S _e

5. look into modulation signal figure (consulting Figure 10) according to current operation angle θ and obtain sine wave signal M _a, M _b

6. T _TempAnd M _aMultiply each other, product is sent into comparand register 1; T _TempAnd M _bMultiply each other, 1 deducts the difference that product obtains sends into comparand register 2;

7. the inner comparand register of digital signal processor relatively generates pulse width signal S _a, S _bOutput to switching tube and select circuit; With wayside signaling S _eOutput to switching tube and select circuit (consulting Figure 11).

Figure 12 selects circuit diagram for switching tube.Will be by the two-way pulse width signal S of digital signal processor input _aAnd S _bSeparately negate and with after obtain another road pulse width signal S _c, 1 decoding generates a group address to digital signal processor according to current place section scale-checking, passes through S _eHolding wire is sent to switching tube and selects circuit, switching tube is selected 3 74HC164 in the circuit that this group address is carried out serial/parallel conversion and is latched, 68 of gatings select a certain road input signal in 1 device to make its output respectively then, and switching tube selects the drive signal of circuit generation through drive circuit driving power switch.

Table 1

Interval	I	?II	?III	?IV	?V	?VI
							S c	S SP	?S RN	?S TP	?S SN	?S RP	?S TN
S a	S RP	?S SN	?S SP	?S TN	?S TP	?S RN
							S b	S TP	?S TN	?S RP	?S RN	?S SP	?S SN
ON	S SN	?S RP	?S TN	?S SP	?S RN	?S TP
							OFF	S RNS TN	?S TP?S SP	?S RN?S SN	?S RP?S TP	?S TN?S SN	?S RP?S SP

Claims (4)

1. the control device of a boost three-phase grid-connected inverting system, comprise a digital signal processor (3), it is characterized in that: detect the electric current supplied with digital signal processor (3) that flows through DC filter in the main circuit (7) by a current sensor (5), a voltage sensor (1) detects a R phase voltage input line voltage zero-crossing detector (2) of three phase network, described line voltage zero-crossing detector (2) carries out supplied with digital signal processor (3) after the signal processing with the R phase voltage of input, digital signal processor (3) carries out pulse-width modulation and interval calculating back output two pulse signals and a switching tube selection of one road wayside signaling input circuit (4) according to the current signal and the voltage zero-crossing signal of input, described switching tube selects circuit (4) according to the wayside signaling of input the pulse signal of importing to be carried out exporting six tunnel drive signals behind the signal condition, and switching tube selects a drive signal drive circuit of input (6) of circuit (4) output to isolate and power amplification rear drive main circuit (7).

2. the control device of boost three-phase grid-connected inverting system according to claim 1, it is characterized in that described switching tube selects circuit (4) to select 1 device 74HCl51 or 74HC251 or 74HC354 or other identical function device to form by 3 address latch 74HCl64 and 68, the two-way pulse width signal S that will import by digital signal processor _aAnd S _bSeparately negate and with after obtain another road pulse width signal S _c, 8 select the wayside signaling S of 1 circuit according to input _eWith 3 road pulse width signal S _a, S _b, S _cConditioning generates 6 tunnel drive signals and outputs to drive circuit (6).

3. the control device of boost three-phase grid-connected inverting system according to claim 1 is characterized in that described drive circuit (6) adopts the EXB841 of FUJI ELECTRIC or HR065 or the M57962L of Mitsubishi or PC923 or the HCPL-3120 of Agilent or the IR2110 or the IR2130 drive circuit of HCPL-316J or American I R company of Sharp that Japanese English reaches.

4. control method that is used for according to right 1 described boost three-phase grid-connected inversion control device is characterized in that controlled step is as follows:

1. the current i that current sensor (5) is detected _LVoltage zero-crossing signal U with line voltage zero-crossing detector (2) generation _RBe input to digital signal processor (3);

2. digital signal processor (3) calculates the grid-connected current coefficient according to grid-connected current $k=\frac{{2\sqrt{2}V}_g}{{3\mathrm{Ui}}_L^{*}};$

3. k and i _LMultiply each other, product is sent into temporary register T _Temp

4. according to voltage zero-crossing signal U _RCalculate current operation angle θ and wayside signaling S _e

5. look into modulation signal figure according to current operation angle θ and obtain sine wave signal M _a, M _b

6. T _TempAnd M _aMultiply each other, product is sent into comparand register 1;

T _TempAnd M _bMultiply each other, 1 deducts the difference that product obtains sends into comparand register 2;

7. the inner comparand register of digital signal processor (3) relatively generates pulse width signal S _a, S _bOutput to switching tube and select circuit; With wayside signaling S _eOutput to switching tube and select circuit.

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