CN106024455A - Non-arcing hybrid DC circuit breaker and method for achieving non-arcing breaking and closing - Google Patents

Abstract

The invention discloses a non-arcing hybrid DC circuit breaker and a method for achieving non-arcing breaking and closing belonging to the technical field of DC circuit breakers. The non-arcing hybrid DC circuit breaker CB comprises a silicon controlled rectifier SCR, a mechanical switch K, a power supply side capacitor C1, a load side capacitor C2, a resistor R, diodes D1 and D2 and a current limiting inductor L, wherein a positive electrode and a negative electrode of the silicon controlled rectifier SCR are connected with two ends of the mechanical switch K. The non-arcing hybrid DC circuit breaker simultaneously meets an arcing electric field intensity condition and an arcing voltage condition of dielectric breakdown when designed aiming at the arc generation requirements; a certain safety allowance is considered; no arc is generated in the breaking and closing processes; the condition that a DC arc is difficult to extinguish after being generated is thoroughly avoided; a mechanical contact is not corroded; a fully-controlled power device and an additional auxiliary mechanical switch are not needed; the control is simple; the cost is low; and the reliability is high.

Description

The chopper of mixed DC without electric arc and realizing without the method for electric arc divide-shut brake

Technical field

The invention belongs to dc circuit breaker technical field, without electric arc mixed DC chopper and realize nothing particularly to one The method of electric arc divide-shut brake.

Background technology

Low-voltage direct power system is mainly used in the occasions such as track traffic, naval vessel, aviation, mesohigh DC transmission system It is mainly used in remote bulk power transmission and the networking of asynchronous AC system, has that track investment is few, it is steady to there is not system Determine problem, regulate the advantages such as quick, reliable.Although different application place straight-flow system operation characteristic obvious difference, but all This core power of dc circuit breaker is needed to equip.

Existing dc circuit breaker is broadly divided into mechanical type, all solid state formula of power electronics and machinery, power electronics combines Hybrid.Wherein mechanical type and hybrid be mostly conceived to how to extinguish electric arc, but make direct current without natural zero-crossing this characteristic of point The extinguishing of electric arc relatively alternating current arc is more difficult, and the erosion of contact is caused chopper frequently to keep in repair by electric arc, reduces and is System reliability.The all solid state dc circuit breaker of power electronic devices composition can cut-off without arc, but is limited to power device capacity, Being applied to during high pressure field need big metering device connection in series-parallel, cause structure and control complexity, reliability is low, just there is also system simultaneously The shortcomings such as when often running, loss is big, with high costs.Chinese invention patent CN103632895A " a kind of dc circuit breaker " proposes A kind of direct-current breaker topology cut-off without electric arc and control method thereof, but when this patent of invention does not illustrate how to guarantee to cut-off Produce without electric arc；And the multiple auxiliary mechanical switchs cooperation of this dc circuit breaker needs, causing controlling complexity, reliability drops Low；There is combined floodgate arcing problems.

Summary of the invention

The purpose of the present invention is to propose to a kind of Arc-free mixed DC chopper and realize the method without electric arc divide-shut brake； It is characterized in that, this Arc-free mixed DC chopper need to meet rising of dielectric breakdown when design for generation electric arc simultaneously Arc electric field intensity condition and arcing voltage condition；And consider certain safety allowance；

This includes IGCT SCR, mechanical switch K, mains side electric capacity C without electric arc mixed DC chopper CB₁, load-side electricity Hold C₂, resistance R, diode D₁、D₂With current-limiting inductance L；Wherein, IGCT SCR anode, negative electrode are connected in parallel on mechanical switch K two ends； Mechanical switch K connects one end of IGCT SCR anode and connects mains side electric capacity C₁Positive pole, mains side equivalent resistance R_SOne end, its Common node is i.e. direct current power system mains side positive pole 1₊；Mechanical switch K connects one end of IGCT SCR negative electrode and connects resistance R one end, diode D₁Negative electrode and current-limiting inductance L one end；The resistance R other end connects diode D₁Anode, load-side electric capacity C₂Just Pole；The current-limiting inductance L other end connects diode D₂Negative electrode, direct current power system load positive pole 2₊；Mains side electric capacity C₁Negative pole connects Straight-flow system mains side negative pole 1_‐, load-side electric capacity C₂Negative pole, diode D₂Anode, direct current power system load negative pole 2_-。

Described direct current power system loads by load-side resistance R_LWith load-side inductance L_LIt is composed in series.

Described direct current power system power supply is by mains side equivalent resistance R_S, mains side equivalent inductance L_SWith DC source U_DCString Connection is constituted.

Described Arc-free mixed DC chopper realizes including without the method for electric arc divide-shut brake:

(1) without electric arc mixed DC chopper CB parameter designing, want with cut-offfing according to given direct current power system parameter Ask, as follows based on the chopper CB parameter designing of mixed DC without electric arc having suppressed arc condition principle:

1) for avoiding short circuit current excessive, except when shortening short circuit current rising by raising mechanical switch K speed of action Outside between, in addition it is also necessary to limiting short-circuit current climbing, set up contact the most accordingly and separate moment DC source current equation.

2) for avoiding DC source to produce vibration, the mains side RLC second-order system overdamp after contact need to be made to separate, then evidence This sets up overdamp equation.

3) according to suppression starting the arc principle, the voltage side in mechanical switch K voltage build-up rate maximum moment after contact separates is set up Journey.

4) simultaneous solution current equation, overdamp equation and voltage equation, obtains mains side electric capacity C₁, load-side electric capacity C₂ With current-limiting inductance L parameter.

5) being quickly to discharge load-side energy, terminate interrupting process, resistance R should make the reverse back loading of current-limiting inductance L electric current Side RLC second-order system critical damping.

(2) without electric arc mixed DC chopper CB running, before cut-offfing rated current without electric arc mixed DC chopper, Direct current power system is properly functioning, diode D₁It is in blocking state, ignores pressure drop on mechanical switch K, mains side electric capacity C₁Voltage Equal to load-side electric capacity C₂Voltage.After mechanical switch K contact separates, its two ends potential difference has diode D₁The saltus step of conduction voltage drop, Diode D before separating due to contact when cut-offfing short circuit current₁Have been turned on, so there is not this voltage jump.Cut-off specified electricity During stream, load-side electric capacity C₂Voltage ratio declines slower when cut-offfing short circuit current, starting the arc electric field intensity is unsatisfactory for, but in order to suppress Arc voltage condition, diode D₁Conduction voltage drop cannot be greater than threshold voltage, limits diode D₁The single tube of multipotency series connection Number is that single tube is pressure without electric arc mixed DC chopper CB highest voltage level is multiplied by limit series connection number；Detailed process includes:

Making process: after receiving combined floodgate order without electric arc mixed DC chopper CB, first conducting thyristor SCR, then closes Close mechanical switch K contact；Owing to mechanical switch K two ends potential difference is kept less than the IGCT SCR conduction voltage drop of threshold voltage, Arcing voltage condition is unsatisfactory for, and will not produce electric arc in making process；After IGCT SCR conducting, mains side electric capacity C₁From initially The DC source U of state_DCFloating voltage starts electric discharge, load-side electric capacity C₂Started to charge up from no-voltage by resistance R；Machinery leaves Close pressure drop after K contact completely attaches to turn off less than IGCT SCR conduction voltage drop, IGCT SCR.

Steady operational status: without electric arc mixed DC chopper CB close a floodgate terminate after enter steady operational status, electric current from The mechanical switch K of Guan Bi flows through, and IGCT SCR is in blocking state；Mains side electric capacity C₁Without discharge and recharge, voltage is maintained at power supply Voltage U_DC；Load-side electric capacity C₂Without discharge and recharge, ignoring pressure drop on mechanical switch K, voltage is maintained at supply voltage U_DC；Resistance R without Electric current flows through；Diode D₁It is in blocking state, the most pressure system nominal voltage being half；Current-limiting inductance L is equivalent to Short circuit.During stable operation, can be equivalent to a section lead without electric arc mixed DC chopper CB, conduction loss is low.

Cut-off short circuit current process: after electric arc mixed DC chopper CB leading-out terminal short circuit, mains side electric capacity C₁, load Lateral capacitance C₂With current-limiting inductance L composition equivalence second-order circuit, limiting short-circuit current rises；After receiving separating brake order, mechanical switch K Beginning action, after contact separates, DC source U_DC, mains side equivalent inductance L_S, mains side equivalent resistance R_SWith mains side electricity Hold C₁Composition second order loop, load-side electric capacity C₂, diode D₁, current-limiting inductance L form another second order loop；Mains side electric capacity C₁With load-side electric capacity C₂It is respectively mains side electric current and load-side electric current provides freewheeling path, and maintain mechanical switch K two ends Potential difference is slowly varying.After mechanical switch K contact separates, its two ends potential difference is from the beginning of an initial value less than threshold voltage Slowly rising, when minimum contact pitch, electric field intensity is the biggest, and starting the arc electric field intensity condition meets, but arcing voltage Condition is unsatisfactory for, thus without producing electric arc；Increase along with contact pitch, although arcing voltage condition has reached, but electric Field intensity condition is the most satisfied, also will not produce electric arc；After current-limiting inductance L electric current is reverse, diode D₁Turn off, load-side electricity Hold C₂, resistance R, current-limiting inductance L composition second order loop, until load-side electric capacity C₂Storage energy dissipation is complete, mechanical switch K two Terminal potential difference drops to direct current power source voltage.

Cut-off load current process: after mechanical switch K contact separates, mains side working condition and cut-off short circuit current phase With, but load-side is load-side electric capacity C₂, current-limiting inductance L, load inductance L_LWith load resistance R_LThe RLC second-order system of composition.By In the uncertainty of load, the possible overdamp of this second-order system, critical damping or underdamping.If system overdamp or critical Damping, then at load-side electric capacity C₂Voltage drops to zero, current-limiting inductance L and load inductance L_LWhen electric current drops to zero, interrupting process Terminate.If system is vibrated because of underdamping, then after load voltage is reverse, diode D₂Conducting, protects load inductance L_LAnd load Resistance R_LIt is not subject to backward voltage and electric current, current-limiting inductance L and electric capacity C₂, resistance R form load-side RLC second-order system, until negative Carrying side energy release complete, interrupting process terminates.

The invention has the beneficial effects as follows and need to meet dielectric breakdown field intensity condition (starting the arc electric field intensity for generation electric arc simultaneously Condition) and arcing voltage condition；And consider certain safety allowance, take one less than the threshold voltage of minimum arcing voltage and one Less than the threshold electric field intensity of minimum starting the arc electric field intensity, when making different in interrupting process, mechanical switch K two ends potential difference occurs Overcome higher than the situation of threshold electric field intensity higher than electric field intensity between threshold voltage and contact；Cut-offfing, in making process All producing without electric arc, thoroughly avoid the situation being difficult to extinguish after direct-current arc produces, mechanical contact is without any erosion, and is not required to Full control power device and extra auxiliary mechanical switch, control simple, low cost, and reliability is high.

Accompanying drawing explanation

Fig. 1 has been arc condition schematic diagram；

Fig. 2 is arcing voltage probability density distribution figure；

Fig. 3 is that interrupting process suppresses starting the arc schematic diagram；

Fig. 4 is circuit theory diagrams；

Fig. 5 is the equivalent circuit theory figure of making process；

Fig. 6 is the equivalent circuit theory figure that system is properly functioning；

Fig. 7 is short circuit current ascent stage equivalent circuit theory figure before contact separates；

Fig. 8 is the equivalent circuit theory figure cut-offfing the short circuit current first stage；

Fig. 9 is the effect circuit theory diagrams cut-offfing short circuit current second stage etc..

Detailed description of the invention

The present invention proposes a kind of Arc-free mixed DC chopper and realizes the method without electric arc divide-shut brake；Below in conjunction with The present invention is further described for drawings and Examples.

Circuit theory diagrams as shown in Figure 4, this Arc-free mixed DC chopper needs for generation electric arc when design Meet starting the arc electric field intensity condition and the arcing voltage condition of dielectric breakdown simultaneously；And consider certain safety allowance.This is without electric arc Mixed DC chopper CB includes IGCT SCR, mechanical switch K, mains side electric capacity C₁, load-side electric capacity C₂, resistance R, diode D₁、D₂With current-limiting inductance L；Wherein, IGCT SCR anode, negative electrode are connected in parallel on mechanical switch K two ends；Mechanical switch K connects brilliant lock One end of pipe SCR anode connects mains side electric capacity C₁Positive pole, mains side equivalent resistance R_SOne end, its common node is i.e. direct current Electric power system power source side positive pole 1₊；Mechanical switch K connects one end of IGCT SCR negative electrode and connects resistance R one end, diode D₁Cloudy Pole and current-limiting inductance L one end；The resistance R other end connects diode D₁Anode, load-side electric capacity C₂Positive pole；The current-limiting inductance L other end Connect diode D₂Negative electrode, direct current power system load positive pole 2₊；Mains side electric capacity C₁Negative pole connects straight-flow system mains side negative pole 1_‐, load-side electric capacity C₂Negative pole, diode D₂Anode, direct current power system load negative pole 2_‐.Wherein, direct current power system load By load-side resistance R_LWith load-side inductance L_LIt is composed in series.Direct current power system power supply is by mains side equivalent resistance R_S, mains side Equivalent inductance L_SWith DC source U_DCIn series.

Suppression starting the arc principle

The generation of electric arc need to meet dielectric breakdown field intensity condition (starting the arc electric field intensity condition) and arcing voltage condition simultaneously. Theoretical according to high voltage, standard atmosphere pressure air breakdown field intensity is about 3 × 10⁶V/m.Electric arc substantially divides in whole developmental stage It is three periods: metal bridge stage, metallic phase arc stage, gaseous phase arc stage, the wherein initial electricity of metal phase voltage platform Pressure is then arcing voltage.Arcing voltage is mainly made up of two parts, and its value depends on energy needed for stable electric arc: in cathode material Electronics free charge to be become, first have to overcome the constraint of metallic atom, work function eU need to be overcome_e；Form electric arc, it is desirable to electricity Son can ionized metal steam, need to do work eU_i.Different mechanical contact material arcing voltages are slightly different, and electrical circuitry equipment is conventional to be had Non-ferrous metal arcing voltage is about 12V.

According to Fig. 1, a large amount of direct currents cut-off the direct-current arc that experimental result counts and play arc condition schematic diagram.Transverse axis in figure DC source rated voltage, the longitudinal axis is maximum field intensity between mechanical contact in interrupting process, and in coordinate system, any position represents One time direct current cut-offs experiment particular job state.According to the starting the arc probability coordinate system can be divided into four regions: I starting the arc district, II Transition region, III safety allowance district, IV not starting the arc district.I starting the arc district DC source rated voltage is higher than the highest arcing voltage, and machinery touches Between Tou, maximum electric field intensity is higher than the highest not starting the arc electric field intensity, and starting the arc probability is 100%；II transition region supply voltage is higher than Low arcing voltage, maximum electric field intensity is higher than minimum starting the arc electric field intensity, and starting the arc probability is 0～100%；III safety allowance district and IV not starting the arc district supply voltage is less than minimum arcing voltage, or maximum electric field intensity is less than minimum starting the arc electric field intensity, the starting the arc Probability is 0.Consider certain safety allowance, take a threshold voltage U less than minimum arcing voltage_TWith one less than the minimum starting the arc Threshold electric field intensity E of electric field intensity_T, voltage is less than threshold voltage U_T, or electric field intensity is less than threshold electric field intensity E_TDistrict Territory is then IV not starting the arc district.IV not starting the arc district can be divided into U < U_T, E > E_TA district, U < U_T, E < E_TB district and U > U_T, E < E_TC district. According to experimental result desirable threshold electric field intensity E_T=5 × 10⁵V/m, this electric field intensity is far below high voltage theory Plays air Pressure air breakdown field intensity 3 × 10⁶V/m, it can be ensured that less than E_TElectric field intensity will not puncture contact gap.As shown in Figure 2 straight The probability density distribution of stream Arc voltage, experiment chromium-zirconium-copper contact arcing voltage used is 11～17V, and is concentrated mainly on Near 14V, so desirable threshold voltage U_T=10V.

The arc condition schematic diagram that rises shown in Fig. 2 is to cut-off the particular job statistic of experiment by a large amount of direct currents to obtain, Therefore can regard single direct current as and cut-off possible duty.Now, transverse axis is contact two ends potential difference, the longitudinal axis in interrupting process For electric field intensity between contact, in coordinate system, any position represents that this moment direct current cut-offs duty.Mixed DC without electric arc breaks Wish during the device action of road that operating point is always positioned at IV not starting the arc district, but when just cut-offfing without electric arc mixed DC chopper between contact Away from minimum, electric field intensity is it is difficult to ensure that be less than threshold electric field intensity E_T, so operating point is positioned at B district and is difficult to, actual cut-off Time can control operating point in A, C district, thus ensure to cut-off without arc.

Fig. 3 is to have suppressed arc condition schematic diagram without electric arc mixed DC chopper interrupting process in the present invention.When machinery leaves When pass K contact pitch is d, according to threshold electric field intensity E_TNot starting the arc safe voltage u determined_T=E_TD, mechanical switch K voltage u_K =u_C1‐u_C2, after mechanical switch K contact separates, its voltage u_KStart slowly to rise less than the initial value of threshold voltage from one, During minimum contact pitch, electric field intensity is the biggest, u_K>u_T, u_K<U_T, starting the arc electric field intensity condition meets, but arcing voltage Condition is unsatisfactory for, and thus without producing electric arc, operating point is positioned at A district；Along with the increase of contact pitch, u_K<u_T, u_K>U_T, although Arcing voltage condition has reached, but electric field intensity condition is the most satisfied, also will not produce electric arc, and operating point is positioned at C district, until Contact reach specified open away from.

The chopper CB work process of mixed DC without electric arc

Making process

As it is shown in figure 5, after receiving combined floodgate order without electric arc mixed DC chopper CB, first conducting thyristor SCR, then closes Close mechanical switch K contact.Due to mechanical switch K two ends potential difference u_KIt is kept less than threshold voltage U_TIGCT SCR conducting pressure Fall, arcing voltage condition is unsatisfactory for, and will not produce electric arc in making process.After mechanical switch K contact completely attaches to, pressure drop is less than IGCT SCR conduction voltage drop, IGCT SCR turns off.Ignore IGCT SCR conduction voltage drop and mechanical switch K contact completely attaches to Rear pressure drop, making process equivalent circuit is as shown in Figure 5.After IGCT SCR conducting, mains side electric capacity C₁From original state unidirectional current Source U_DCFloating voltage starts electric discharge, load-side electric capacity C₂Started to charge up from no-voltage by resistance R.

Combined floodgate terminates rear steady operational status

As shown in Figure 6, when terminating rear stable operation without electric arc mixed DC chopper CB combined floodgate, electric current is from the machinery of Guan Bi Switch K flows through, and IGCT SCR is in blocking state；Mains side electric capacity C₁Without discharge and recharge, voltage is maintained at supply voltage；Load Lateral capacitance C₂Without discharge and recharge, ignoring pressure drop on mechanical switch K, voltage is maintained at system power source voltage；Resistance R no current flows through； Diode D₁It is in blocking state, the most pressure system nominal voltage being half；Current-limiting inductance L is equivalent to short circuit.Stable During operation, can be equivalent to a section lead without electric arc mixed DC chopper CB, conduction loss is low.

Cut-off short circuit current process

Fig. 7 be without electric arc mixed DC chopper CB leading-out terminal short circuit after, mechanical switch K contact separate before on short circuit current Rise stage equivalent circuit diagram.Ignore mechanical switch K pressure drop and diode D₁Pressure drop, mains side electric capacity C₁, load-side electric capacity C₂Can see Become the in parallel bulky capacitor that capacitance is C, ignore mains side equivalent inductance L much smaller than current-limiting inductance L_S, without electric arc direct current interruption Device CB can be equivalent to second-order circuit, and limiting short-circuit current rises.Load inductance L_LBy load resistance R_LElectric discharge, until stored Energy dissipation is complete.

Fig. 8 is the equivalent circuit diagram cut-offfing the leading-out terminal short circuit current first stage without electric arc mixed DC chopper CB.Nothing After electric arc mixed DC chopper CB receives separating brake order, mechanical switch K starts action, after contact separates, and DC source U_DC、 Mains side equivalent inductance L_S, mains side equivalent resistance R_SWith mains side electric capacity C₁Composition RLC second-order circuit, load-side electric capacity C₂, two Pole pipe D₁, current-limiting inductance L composition LC second-order circuit.Mechanical switch K two ends potential difference u_K=u_C1‐u_C2, mechanical switch K contact separates After, its two ends potential difference u_KStart slowly to rise less than the initial value of threshold voltage from one, when minimum contact pitch, electricity Field intensity is the biggest, u_K>u_T, u_K<U_T, starting the arc electric field intensity condition meets, but arcing voltage condition is unsatisfactory for, thus without Produce electric arc operating point and be positioned at A district；Along with the increase of contact pitch, u_K<u_T, u_K>U_T, although arcing voltage condition has reached, But electric field intensity condition is the most satisfied, also will not produce electric arc, operating point is positioned at C district.

Fig. 9 is the equivalent circuit diagram cut-offfing leading-out terminal short circuit current second stage without electric arc mixed DC chopper CB.When After current-limiting inductance L electric current is reverse, diode D₁Turn off, load-side electric capacity C₂, resistance R, current-limiting inductance L composition second order loop, until Load-side electric capacity C₂Storage energy dissipation is complete, and mechanical switch K two ends potential difference drops to direct current power source voltage.

Cut-off load current process

After mechanical switch K contact separates, mains side working condition and identical when cut-offfing short circuit current, but load-side is for loading Lateral capacitance C₂, current-limiting inductance L, load inductance L_LWith load resistance R_LThe RLC second-order system of composition.Due to the uncertainty of load, The possible overdamp of this second-order system, critical damping or underdamping.If system overdamp or critical damping, then at load-side electricity Hold C₂Voltage drops to zero, current-limiting inductance L and load inductance L_LWhen electric current drops to zero, interrupting process terminates.If system is because owing resistance Buddhist nun and vibrate, then load voltage reversely after, diode D₂Conducting, protects load inductance L_LWith load resistance R_LIt is not subject to reversely Voltage and current, current-limiting inductance L and electric capacity C₂, resistance R form load-side RLC second-order system, until load-side energy releases Finishing, interrupting process terminates.

The chopper CB Parameters design of mixed DC without electric arc

Known direct current power system parameter: DC source floating voltage U_DC, system nominal voltage U_n, system nominal current I_n, mains side equivalent inductance L_S, mains side equivalent resistance R_S.In order to realize cut-offfing without arc, it is reasonable to need according to suppression starting the arc principle Design mains side electric capacity C₁, load-side electric capacity C₂, current-limiting inductance L and resistance R parameter, method is as follows:

1) for avoiding short circuit current excessive, except when shortening short circuit current rising by raising mechanical switch K speed of action Outside between, in addition it is also necessary to limiting short-circuit current climbing, set up contact the most accordingly and separate moment DC source current equation.

2) for avoiding DC source to produce vibration, the mains side RLC second-order system overdamp after contact need to be made to separate, then evidence This sets up overdamp equation.

3) according to suppression starting the arc principle, the voltage side in mechanical switch K voltage build-up rate maximum moment after contact separates is set up Journey.

4) simultaneous solution current equation, overdamp equation and voltage equation, obtains mains side electric capacity C₁, load-side electric capacity C₂ With current-limiting inductance L parameter.

5) being quickly to discharge load-side energy, terminate interrupting process, resistance R should make the reverse back loading of current-limiting inductance L electric current Side RLC second-order system critical damping.

Before contact separates: 0≤t < t_d

After Fig. 7 show breaker outgoing line terminal shortcircuit, before mechanical switch K contact separates, short circuit current ascent stage etc. Effect circuit diagram.Ignore mechanical switch K and diode D₁Pressure drop, mains side electric capacity C₁, load-side electric capacity C₂Can parallel equivalent be electric capacity C, ignores mains side equivalent inductance L much smaller than current-limiting inductance L simultaneously_S, RLC second order electricity can be equivalent to without arc dc circuit breaker Road, its original state is:

u_C(0)=U_n, i_L(0)=I_n (1)

Before contact separates, equivalent parallel electric capacity C voltage is:

$u_C=A_1{e}^{-(\mathrm{\&alpha;}+\sqrt{{\mathrm{\&alpha;}}^2-{\mathrm{\&omega;}}^2})t}+A_2{e}^{-(\mathrm{\&alpha;}-\sqrt{{\mathrm{\&alpha;}}^2-{\mathrm{\&omega;}}^2})t}---\left(2\right)$

Wherein: C=C₁+C₂, α=1/2R_SC,

$A_1=\frac{(\sqrt{L^2-4{\mathrm{LCR}}_S^2}+L)U_n}{2\sqrt{L^2-4{\mathrm{LCR}}_S^2}},A_2=\frac{(\sqrt{L^2-4{\mathrm{LCR}}_S^2}-L)U_n}{2\sqrt{L^2-4{\mathrm{LCR}}_S^2}}$

Before contact separates, current-limiting inductance L electric current is:

$i_L=\frac{U_{DC}}{R_S}+A_3{e}^{-(\mathrm{\&alpha;}+\sqrt{{\mathrm{\&alpha;}}^2-{\mathrm{\&omega;}}^2})t}+A_4{e}^{-(\mathrm{\&alpha;}-\sqrt{{\mathrm{\&alpha;}}^2-{\mathrm{\&omega;}}^2})t}---\left(3\right)$

Wherein:

$A_3=\frac{(\sqrt{L^2-4{\mathrm{LCR}}_S^2}-L)U_{DC}}{2R_S\sqrt{L^2-4{\mathrm{LCR}}_S^2}}+\frac{(L-\sqrt{L^2-4{\mathrm{LCR}}_S^2}){\mathrm{RI}}_n+2R_S{\mathrm{CU}}_n}{2R_S\sqrt{L^2-4{\mathrm{LCR}}_S^2}}$

$A_4=\frac{(-\sqrt{L^2-4{\mathrm{LCR}}_S^2}-L)U_{DC}}{2R_S\sqrt{L^2-4{\mathrm{LCR}}_S^2}}+\frac{(L+\sqrt{L^2-4{\mathrm{LCR}}_S^2}){\mathrm{RI}}_n+2R_S{\mathrm{CU}}_n}{2R_S\sqrt{L^2-4{\mathrm{LCR}}_S^2}}$

Before contact separates, DC source U_DCElectric current is:

i_DC=(U_DC-u_C)/R_S (4)

Limiting the average climbing of DC source short circuit current is r, then separate the DC source electric current in moment according to contact, build Vertical with mains side electric capacity C₁, load-side electric capacity C₂It is the current equation of unknown quantity with current-limiting inductance L:

$i_{DC}(C_1,C_2,L,t){|}_{t=t_d}=I_n+{\mathrm{rt}}_d---\left(5\right)$

After contact separates: t_d≤t≤t_b

As shown in Figure 8, after mechanical switch K contact separates, DC source U_DC, mains side equivalent inductance L_S, equivalent resistance R_S With mains side electric capacity C₁Composition mains side RLC second-order system, its original state is:

$u_{C1}^{\&prime;}\left(t_d\right)=u_C\left(t_d\right),i_{L_S}^{\&prime;}\left(t_d\right)=i_{DC}\left(t_d\right)---\left(6\right)$

After contact separates, mains side electric capacity C₁Voltage is:

$\begin{array}{c}{u}_{C1}^{\&prime;}=U_{DC}+A_5{e}^{-({\mathrm{\&alpha;}}_1+\sqrt{{{\mathrm{\&alpha;}}_1}^2-{{\mathrm{\&omega;}}_1}^2})(t-t_d)}+\\ A_6{e}^{-({\mathrm{\&alpha;}}_1-\sqrt{{{\mathrm{\&alpha;}}_1}^2-{{\mathrm{\&omega;}}_1}^2})(t-t_d)}\end{array}---\left(7\right)$

Wherein: α₁=R_S/2L_S,

$A_5=\frac{(R_S{C}_1-\sqrt{R_S^2{C}_1^2-4L_S{C}_1})U_{DC}}{2\sqrt{R_S^2{C}_1^2-4L_S{C}_1}}+\frac{(\sqrt{R_S^2{C}_1^2-4L_S{C}_1}-R_S{C}_1)u_C\left(t_d\right)-2L_S{i}_{DC}\left(t_d\right)}{2\sqrt{R_S^2{C}_1^2-4L_S{C}_1}}$

$A_6=\frac{(-R_S{C}_1-\sqrt{R_S^2{C}_1^2-4L_S{C}_1})U_{DC}}{2\sqrt{R_S^2{C}_1^2-4L_S{C}_1}}+\frac{(\sqrt{R_S^2{C}_1^2-4L_S{C}_1}+R_S{C}_1)u_C\left(t_d\right)+2L_S{i}_{DC}\left(t_d\right)}{2\sqrt{R_S^2{C}_1^2-4L_S{C}_1}}$

For avoiding DC source to vibrate, mains side electric capacity C₁Mains side RLC second-order system overdamp, i.e. attenuation constant should be made α₁Should be greater than nature hunting angle frequencies omega₁, so:

$C_1>4L_S/R_S^2---\left(8\right)$

Taking 10% allowance, obtaining overdamp equation is:

$C_1=4.4L_S/R_S^2---\left(9\right)$

As shown in Figure 4, diode D is ignored₁With minimum short-circuit impedance, after mechanical switch K contact separates, current-limiting inductance L Before electric current is reverse, load-side electric capacity C₂Forming load-side LC second-order system with current-limiting inductance L, its original state is:

u′_C2(t_d)=u_C(t_d), i '_L(t_d)=i_L(t_d) (10)

After contact separates, load-side electric capacity C₂Voltage is:

$\begin{array}{c}{u}_{C2}^{\&prime;}={\mathrm{\&omega;}}_2^2{u}_C\left(t_d\right)cos\&lsqb;{\mathrm{\&omega;}}_2(t-t_d)\&rsqb;-\\ \frac{{\mathrm{\&omega;}}_2}{C_2}{i}_L\left(t_d\right)\sin \&lsqb;{\mathrm{\&omega;}}_2(t-t_d)\&rsqb;\end{array}---\left(11\right)$

Wherein:

After contact separates, mechanical switch K voltage is:

u_K=u '_C1-u′_C2 (12)

Mechanical switch K contact is after isolation with speed V_KAt the uniform velocity disconnect, according to threshold electric field intensity E_TThe not starting the arc electricity determined Pressure u_TFor:

u_T=E_TD=E_TV_K(t-t_d) (13)

T=t_bMoment, load-side electric capacity C₂Voltage reduces to zero, but now load-side electric capacity C₂Discharge current reaches maximum, Causing mechanical switch K voltage build-up rate to reach maximum, electric field intensity reaches arcing voltage condition and meets later peak, because of As long as this ensures that now electric field intensity is not higher than threshold electric field intensity, starting the arc electric field intensity and voltage conditions just can not be expired simultaneously Foot.Thus obtain voltage equation:

$u_K(C_1,C_2,L,t){|}_{t=t_b}=u_T(C_1,C_2,L,t){|}_{t=t_b}---\left(14\right)$

Simultaneous solution current equation (6), overdamp equation (10) and voltage equation (15), obtain mains side electric capacity C₁, negative Carry lateral capacitance C₂With current-limiting inductance L parameter.

Current-limiting inductance L electric current reversely after: t > t_b

Fig. 9 is the equivalent circuit diagram cut-offfing leading-out terminal short circuit current second stage without electric arc mixed DC chopper CB.When After current-limiting inductance L electric current is reverse, diode D₁Turn off, load-side electric capacity C₂, resistance R, current-limiting inductance L composition RLC second order loop, For quickly release load-side energy, terminating interrupting process, resistance R should make this RLC second-order system critical damping, it may be assumed that

$R=2\sqrt{L/C_2}---\left(15\right)$

The chopper CB highest voltage level of mixed DC without electric arc

Before the CB of dc circuit breaker without electric arc cut-offs rated current, direct current power system is properly functioning, diode D₁It is in resistance Disconnected state, ignores pressure drop on mechanical switch K, mains side electric capacity C₁Voltage is equal to load-side electric capacity C₂Voltage.Mechanical switch K contact After separation, its voltage has diode D₁Conduction voltage drop U_DSaltus step, diode D before separating due to contact when cut-offfing short circuit current₁? Through conducting, so there is not this voltage jump.When cut-offfing rated current, load-side electric capacity C₂Voltage ratio cut-offs short circuit current at present Fall is slower, and starting the arc electric field intensity is unsatisfactory for, but in order to suppress arcing voltage condition, diode D₁Conduction voltage drop U_DCannot be greater than door Sill voltage U_T, it may be assumed that

U_D≤U_T (16)

Diode D₁Single tube the most pressure for U_R, forward conduction voltage drop is U_F, then diode D₁Series connection single tube number maximum For:

$n_{max}=\frac{U_T}{U_F}---\left(17\right)$

System maximum rated voltage U_nmaxFor:

U_nmax=n_maxU_R (18)。

Claims (4)

1. one kind without electric arc mixed DC chopper；It is characterized in that, this Arc-free mixed DC chopper is at design hour hands Generation electric arc need to be met simultaneously starting the arc electric field intensity condition and the arcing voltage condition of dielectric breakdown；And consider that certain safety is abundant Amount；

This includes IGCT SCR, mechanical switch K, mains side electric capacity C without electric arc mixed DC chopper CB₁, load-side electric capacity C₂、 Resistance R, diode D₁、D₂With current-limiting inductance L；Wherein, IGCT SCR anode, negative electrode are connected in parallel on mechanical switch K two ends；Machinery leaves Close K and connect one end connection mains side electric capacity C of IGCT SCR anode₁Positive pole, mains side equivalent resistance R_SOne end, it saves jointly Point is i.e. direct current power system mains side positive pole 1₊；Mechanical switch K connect IGCT SCR negative electrode one end connect resistance R one end, Diode D₁Negative electrode and current-limiting inductance L one end；The resistance R other end connects diode D₁Anode, load-side electric capacity C₂Positive pole；Current limliting The inductance L other end connects diode D₂Negative electrode, direct current power system load positive pole 2₊；Mains side electric capacity C₁Negative pole connects direct current system System mains side negative pole 1_-, load-side electric capacity C₂Negative pole, diode D₂Anode, direct current power system load negative pole 2_-。

A kind of without electric arc mixed DC chopper；It is characterized in that, described direct current power system is born Carry by load-side resistance R_LWith load-side inductance L_LIt is composed in series.

A kind of without electric arc mixed DC chopper；It is characterized in that, described direct current power system electricity Source is by mains side equivalent resistance R_S, mains side equivalent inductance L_SWith DC source U_DCIn series.

4. realize the method without electric arc divide-shut brake without electric arc mixed DC chopper described in a claim 1, it is characterised in that Including:

(1) without electric arc mixed DC chopper CB parameter designing, according to given direct current power system parameter and cut-off requirement, base In suppression, the chopper CB parameter designing of mixed DC without electric arc of arc condition principle is as follows:

1) for avoiding short circuit current excessive, in addition to shortening the short circuit current rise time by raising mechanical switch K speed of action, Also need to limiting short-circuit current climbing, set up contact the most accordingly and separate moment DC source current equation；

2) for avoiding DC source to produce vibration, the mains side RLC second-order system overdamp after contact need to be made to separate, build the most accordingly Vertical overdamp equation；

3) according to suppression starting the arc principle, the voltage equation in mechanical switch K voltage build-up rate maximum moment after contact separates is set up；

4) simultaneous solution current equation, overdamp equation and voltage equation, obtains mains side electric capacity C₁, load-side electric capacity C₂And limit Stream inductance L parameter；

5) being quickly to discharge load-side energy, terminate interrupting process, resistance R should make current-limiting inductance L electric current reverse back loading side RLC Second-order system critical damping；

(2) without electric arc mixed DC chopper CB running, before cut-offfing rated current without electric arc mixed DC chopper, direct current Power system is properly functioning, diode D₁It is in blocking state, ignores pressure drop on mechanical switch K, mains side electric capacity C₁Voltage is equal to Load-side electric capacity C₂Voltage, after mechanical switch K contact separates, its two ends potential difference has diode D₁The saltus step of conduction voltage drop, cut-offs Diode D before separating due to contact during short circuit current₁Have been turned on, so there is not this voltage jump, when cut-offfing rated current, Load-side electric capacity C₂Voltage ratio declines slower when cut-offfing short circuit current, starting the arc electric field intensity is unsatisfactory for, but in order to suppress starting the arc electricity Press strip part, diode D₁Conduction voltage drop cannot be greater than threshold voltage, limits diode D₁The single tube number of multipotency series connection, nothing Electric arc mixed DC chopper CB highest voltage level is that single tube is pressure is multiplied by limit series connection number；Detailed process includes:

Making process: after receiving combined floodgate order without electric arc mixed DC chopper CB, first conducting thyristor SCR, then close machine Tool switch K contact；Owing to mechanical switch K two ends potential difference is kept less than the IGCT SCR conduction voltage drop of threshold voltage, the starting the arc Voltage conditions is unsatisfactory for, and will not produce electric arc in making process；After IGCT SCR conducting, mains side electric capacity C₁From original state DC source U_DCFloating voltage starts electric discharge, load-side electric capacity C₂Started to charge up from no-voltage by resistance R；Mechanical switch K After contact completely attaches to, pressure drop turns off less than IGCT SCR conduction voltage drop, IGCT SCR；

Steady operational status: closing a floodgate without electric arc mixed DC chopper CB and enter steady operational status after terminating, electric current is from Guan Bi Mechanical switch K flow through, IGCT SCR is in blocking state；Mains side electric capacity C₁Without discharge and recharge, voltage is maintained at supply voltage U_DC；Load-side electric capacity C₂Without discharge and recharge, ignoring pressure drop on mechanical switch K, voltage is maintained at supply voltage U_DC；Resistance R no current Flow through；Diode D₁It is in blocking state, the most pressure system nominal voltage being half；Current-limiting inductance L is equivalent to short circuit, During stable operation, can be equivalent to a section lead without electric arc mixed DC chopper CB, conduction loss is low；

Cut-off short circuit current process: after electric arc mixed DC chopper CB leading-out terminal short circuit, mains side electric capacity C₁, load-side electricity Hold C₂With current-limiting inductance L composition equivalence second-order circuit, limiting short-circuit current rises；After receiving separating brake order, mechanical switch K starts Action, after contact separates, DC source U_DC, mains side equivalent inductance L_S, mains side equivalent resistance R_SWith mains side electric capacity C₁Group Become second order loop, load-side electric capacity C₂, diode D₁, current-limiting inductance L form another second order loop；Mains side electric capacity C₁With negative Carry lateral capacitance C₂It is respectively mains side electric current and load-side electric current provides freewheeling path, and maintain mechanical switch K two terminal potential Difference is slowly varying, and after mechanical switch K contact separates, its two ends potential difference starts slowly less than the initial value of threshold voltage from one Rising, when minimum contact pitch, electric field intensity is the biggest, and starting the arc electric field intensity condition meets, but arcing voltage condition It is unsatisfactory for, thus without producing electric arc；Increase along with contact pitch, although arcing voltage condition has reached, but electric-field strength Degree condition is the most satisfied, also will not produce electric arc；After current-limiting inductance L electric current is reverse, diode D₁Turn off, load-side electric capacity C₂、 Resistance R, current-limiting inductance L composition second order loop, until load-side electric capacity C₂Storage energy dissipation is complete, mechanical switch K two ends electricity Potential difference drops to direct current power source voltage；

Cut-offfing load current process: after mechanical switch K contact separates, mains side working condition is identical with when cut-offfing short circuit current, But load-side is load-side electric capacity C₂, current-limiting inductance L, load inductance L_LWith load resistance R_LThe RLC second-order system of composition, due to The uncertainty of load, the possible overdamp of this second-order system, critical damping or underdamping, if system overdamp or critical resistance Buddhist nun, then at load-side electric capacity C₂Voltage drops to zero, current-limiting inductance L and load inductance L_LWhen electric current drops to zero, interrupting process is tied Bundle, if system is vibrated because of underdamping, then after load voltage is reverse, diode D₂Conducting, protects load inductance L_LWith load electricity Resistance R_LIt is not subject to backward voltage and electric current, current-limiting inductance L and electric capacity C₂, resistance R form load-side RLC second-order system, until load Side energy release is complete, and interrupting process terminates.