CN101593974B - Compound overvoltage protection device and application thereof in semiconductor convertor equipment - Google Patents

Abstract

The invention relates to an overvoltage protection device and an application thereof. ZnO-Bi2O3-TiO2 high-energy zinc oxide varistors and ZnO-Bi2O3-Sb2O3 high-voltage zinc oxide varistors are combined in different modes to form two overvoltage protection devices. One is electrically connected with an alternating current lead-in side of semiconductor convertor equipment, and the other is electrically connected with a direct current side or a convertor output side of the semiconductor convertor equipment. When lightning overvoltage happens, the performance advantages of the ZnO-Bi2O3-Sb2O3 high-voltage zinc oxide varistors can be fully exerted. When switching overvoltage happens, the performance advantages of the ZnO-Bi2O3-TiO2 high-energy zinc oxide varistors are fully exerted. Therefore, the functions of effectively inhibiting the switching overvoltage and the lightning overvoltage are realized. The overvoltage protection device is simple in structure and easy in realization.

Description

Compound overvoltage protection device and the application in the semiconductor variable flow device thereof

Technical field

The present invention relates to a kind of overvoltage protector, relate in particular to a kind of overvoltage protector that is applied in the semiconductor variable flow device.

Background technology

The semiconductor variable flow device is the electric equipment that the voltage of power-supply system, electric current, frequency, waveform, the number of phases and other electric weight or characteristic are carried out conversion, comprises rectifier (AC-DC), inverter (direct current become exchange), chopper, AC voltage regulator, frequency converter and DC-DC converter etc.The semiconductor variable flow device has been widely used in fields such as metallurgy, chemical industry, electric power, mining machinery, communications and transportation at present.The Core Feature parts of semiconductor variable flow device are the various power semiconductor devices that utilize the Si semiconductor technology to produce, and comprise rectifier diode, thyristor and derivation type device, power transistor and derivation type device and efficient electrical power photoelectric device etc.

Because it is relatively poor that power semiconductor device bears superpotential ability, the overvoltage of very short time will be device failure.For making power semiconductor device long-time running reliably,, must take appropriate safeguard measure to the reason that overvoltage takes place except its rated voltage of choose reasonable of fully allowing some leeway, the non-repetitive peak voltage.

Convertor equipment can generally meet with two types overvoltage when operation: switching overvoltage and Lightning Over-voltage.Switching overvoltage be by convertor equipment operate a switch, close a floodgate and in power semiconductor device turn-offs or electromagnetic process such as commutation causes overvoltage; Be characterized in discharge time long (a few tens of milliseconds was by several seconds), the energy of releasing (more than the 1kJ) greatly; But voltage peak and discharging current are generally little, and these switching overvoltages are often generations and unavoidable; Lightning Over-voltage is the sporadic overvoltage surge of invading from electrical network; Be characterized in voltage peak and maximum discharge current very high (tens kV and more than tens kA); But extremely lack discharge time (10～100 μ s), this superpotential energy is generally much smaller than the energy of switching overvoltage.

With the thyristor rectifier is example, and the various overvoltage protection schemes that once adopted in history are as shown in Figure 1.Among Fig. 1, A is a lightning rod; B is transformer shielding winding and ground capacity; C is a coupling capacitance; D is a rc protection circuit; E is the rectifier type rc protection circuit; F is the selenium pile protective circuit; G is a high energy type zinc oxide piezoresistor; H is the device-side rc protection circuit; I is that thyristor is let out the ability circuit.Wherein, A, B, C are the safeguard measures of taking to the overvoltage (comprising Lightning Over-voltage) that is coupled to secondary from the former limit of supply transformer; H is that the safeguard measure, D, E, F, G, the I that take to thyristor commutation overvoltage are to exchanging the safeguard measure that switching overvoltage that input side and unsteady flow outlet side produce is taked, and their effect is basic identical.Since the nineties in last century, with ZnO-Bi ₂O ₃-TiO ₂Be that the high energy type zinc oxide piezoresistor sheet is that the energy-absorbing type thyristor overvoltage protector of core parts (is the G among Fig. 1; Chinese patent ZL200720037734.2, Chinese patent ZL200720037736.1, Chinese patent ZL200420054800.3) come into the market in a large number; And, energy capacity little with volume is big, overvoltage suppresses advantages such as ability is strong and replaced other protection scheme except that A, B and H rapidly, becomes the main product of semiconductor variable flow operation of equipment overvoltage protection.

Under normal conditions; Except semiconductor variable flow device for the power supply of power track vehicular traffic; The secondary of semiconductor variable flow equipment self and supply transformer thereof all is floating ground; And Lightning Over-voltage all occurs between phase line and the earth, therefore has many people to think that this method for designing has natural defensive ability/resistance ability to Lightning Over-voltage.But in actual motion,, cause bigger economic loss to the user because the damage problem of the power semiconductor device that Lightning Over-voltage causes happens occasionally.Below Lightning Over-voltage is smashed the reason of floating the ground convertor equipment and do an analysis.

A thyristor rectifier as shown in Figure 2, the insulation resistance between direct-flow positive pole bus and negative pole bus and the earth is respectively with R ₁And R ₂Expression is when a peak value is ± V _sLightning Over-voltage when any phase line (like the A phase Fig. 2) of AC side is invaded equipment, the positive polarity thunder act on the common anode thyristor or the negative polarity thunder act on the overvoltage U on the common cathode thyristor _ST+Can be expressed as:

$U_{\mathrm{ST}+}=\frac{R_d}{R_d+R_1}{V}_s---\left(1\right)$

The positive polarity thunder act on the common cathode thyristor or the negative polarity thunder act on the overvoltage U on the common anode thyristor _ST-Can be expressed as:

$U_{\mathrm{ST}-}=\frac{R_r}{R_r+R_2}{V}_s---\left(2\right)$

In formula (1) and the formula (2), R _dForward resistance during the not conducting of expression thyristor, R _rBackward resistance during the not conducting of expression thyristor.

In the ideal case, dc bus insulation against ground resistance R ₁And R ₂Be infinity R _dAnd R _rThough equivalent resistance be non-linear but its value all is limited, therefore U under the situation on the floating ground of ideal _ST+And U _ST-Being zero, promptly is that thunderbolt positive polarity or negative polarity can not cause damage to the thyristor in the equipment.But in fact positive and negative dc bus insulation against ground resistance all can not be infinity, can cause the decline of dc bus insulation against ground resistance owing to a variety of causes, even the very little situation of dc bus resistance to earth can occur, so under actual conditions, U _ST+And U _ST-Usually non-vanishing.Can find out from formula (1) and formula (2): R ₁And R ₂Descend seriously more, U _ST+And U _ST-Will be high more, work as U _ST+Value surpassed U _Dsm(non repetitive peak off state voltage of thyristor) or U _ST-Value surpassed U _RsmWhen (non-repetitive peak reverse voltage), over-voltage breakdown will take place thyristor damages.In addition; It can also be seen that from Fig. 2: after a thyristor generation over-voltage breakdown that is total to anode groups or common cathode group; In case other two thyristor conductings that are total to anode groups or common cathode group; Will cause phase fault with the thyristor that has punctured, might not cause by the thyristor generation overcurrent of over-voltage breakdown to puncture, form spreading and enlarging of fault.This situation often takes place at the aluminum electrolysis industry of China, and the direct economic loss that causes every year on average is up to about hundred million yuans.

In addition, exchange among input side generation single phase ground fault and Fig. 1 in the C safeguard measure electric capacity and select improper etc. also can cause lightning strike accident, do not give unnecessary details one by one at this.In a word; The lightning fault that the semiconductor variable flow device takes place all is because a certain phase line of supply transformer secondary or the defective insulation between the electric conductor that links to each other with phase line or element and the earth cause; And in actual motion, it is perfectly safe that the insulation against ground of equipment can not guarantee to accomplish, therefore for the semiconductor variable flow device can long-term safety be moved; Except will protecting, must also to take effective safeguard measure to Lightning Over-voltage to switching overvoltage.

Though A and B safeguard measure have certain inhibitory action to Lightning Over-voltage among Fig. 1, see that from practical effect these two kinds of safeguard measures are obviously not enough to the inhibition ability of Lightning Over-voltage.

In all kinds of overvoltage protections field, Zinc-oxide piezoresistor is that the ratio of performance to price is the highest and use element, wherein ZnO-Bi the most widely ₂O ₃-TiO ₂Be that high energy type zinc oxide piezoresistor and follow-on product (Chinese patent 200910049087.0) have obtained general application (Chinese patent ZL200720037734.2, Chinese patent ZL200720037736.1, Chinese patent ZL200420054800.3) in semiconductor variable flow operation of equipment overvoltage protection; But according to relevant operating specification; High energy type zinc oxide piezoresistor all is used for the differential mode protection; Be about to it and be connected in convertor equipment and exchange between phase line of input side or the outlet side two ends, therefore to occur between phase-ground and output cable-ground between Lightning Over-voltage have no the inhibition ability.In addition, the advantage of high energy type zinc oxide piezoresistor sheet is the big (350～750J/cm of energy capacity ³), strong to the wide impulse current ability to bear of long pulse, but big electric current limit voltage ratio height (current density 30A/cm down ²Under limit voltage ratio 1.80～2.25, current density 2kA/cm ²Under limit voltage ratio 3.8～5.0); Ability to bear to the short pulse duration impulse current is poor; Therefore high energy type zinc oxide piezoresistor only is suitable for the protection of the switching overvoltage that discharging current is little, discharge time is long, surge energy is big, and is not suitable for the protection of the Lightning Over-voltage that discharging current is big, discharge time is short, surge energy is little; Even adopt the mode of common mode protection, with high energy type zinc oxide piezoresistor be connected between phase-ground and output cable-ground between, can not suppress Lightning Over-voltage effectively, but also can make the high energy type zinc oxide piezoresistor accelerated ageing.

Chinese patent 200910049087.0 described high energy type zinc oxide piezoresistors are a kind of products that utilize nano material and nanometer technology that traditional high energy type zinc oxide piezoresistor modification is formed; Though its performance has bigger raising, limit voltage ratio under the big electric current and the stability under the short pulse still can not satisfy the requirement of Lightning Over-voltage protection.

In lightning protection The Application of Technology field,, generally adopt ZnO-Bi as in low-voltage distribution system ₂O ₃-Sb ₂O ₃It is the high-pressure type Zinc-oxide piezoresistor carries out Lightning Over-voltage with the common mode mode of connection protection.The advantage of high-pressure type Zinc-oxide piezoresistor is that current density is big, strong to the ability to bear of short pulse duration impulse current, low (the current density 30A/cm of limit voltage ratio under the big electric current ²Under limit voltage ratio be 1.50～1.84, current density 2kA/cm ²Under limit voltage ratio be 2.3～2.8), but the little (50～300J/cm of energy capacity ³), poor to the ability to bear of the wide impulse current of long pulse.Though therefore the high-pressure type Zinc-oxide piezoresistor is not suitable for the protection of switching overvoltage, and Lightning Over-voltage is had very desirable inhibition effect.

If can be with ZnO-Bi ₂O ₃-TiO ₂Be high energy type zinc oxide piezoresistor and ZnO-Bi ₂O ₃-Sb ₂O ₃Be that the high-pressure type Zinc-oxide piezoresistor is combined, when Lightning Over-voltage takes place, give full play to ZnO-Bi ₂O ₃-Sb ₂O ₃The performance advantage that is the high-pressure type Zinc-oxide piezoresistor is also avoided ZnO-Bi simultaneously ₂O ₃-TiO ₂Be the action of high energy type zinc oxide piezoresistor, and when switching overvoltage takes place, give full play to ZnO-Bi ₂O ₃-TiO ₂The performance advantage that is high energy type zinc oxide piezoresistor is also avoided ZnO-Bi simultaneously ₂O ₃-Sb ₂O ₃Be the action of high-pressure type Zinc-oxide piezoresistor, just can form and a kind ofly can suppress the new product that switching overvoltage can suppress Lightning Over-voltage again effectively effectively.But the action of these two kinds of pressure cells (conducting) all is outer making alive to be triggered, and they self do not judge the ability of overvoltage type and difference action.Therefore the technology that these two kinds of dissimilar piezo-resistances is combined into a product is not seen relevant report so far.

Summary of the invention

The present invention is exactly in order to solve the deficiency of prior art, and a kind of of proposition not only can suppress switching overvoltage effectively, and can suppress the overvoltage protector and the application thereof of Lightning Over-voltage effectively.

In order to reach the foregoing invention purpose, the technical scheme that the present invention adopts is: a kind of compound overvoltage protection device, it comprises ZnO-Bi ₂O ₃-TiO ₂Be high energy type zinc oxide piezoresistor sheet and ZnO-Bi ₂O ₃-Sb ₂O ₃It is the high-pressure type zinc oxide varistor; One end of described high energy type zinc oxide piezoresistor sheet be connected with an end of high-pressure type zinc oxide varistor and since then common connection end draw one and be useful on the semiconductor variable flow device and exchange the splicing ear that input side is electrically connected; Lead to from the other end of described high energy type zinc oxide piezoresistor sheet and to be used for exchanging another splicing ear that input side is electrically connected, draw one from the other end of described high-pressure type zinc oxide varistor and be useful on the splicing ear that is electrically connected with the earth with the semiconductor variable flow device.

In the execution mode to the further optimization of technique scheme, described high energy type zinc oxide piezoresistor sheet is by a ZnO-Bi ₂O ₃-TiO ₂Be piezo-resistance or one group of ZnO-Bi forming through serial or parallel connection ₂O ₃-TiO ₂Be that piezo-resistance constitutes; Described high-pressure type zinc oxide varistor is by a ZnO-Bi ₂O ₃-Sb ₂O ₃Be piezo-resistance or one group of ZnO-Bi forming through serial or parallel connection ₂O ₃-Sb ₂O ₃Be that piezo-resistance constitutes.

The present invention also provides the technical scheme of another kind of compound overvoltage protection device, and it comprises a ZnO-Bi ₂O ₃-TiO ₂Be the ZnO-Bi that high energy type zinc oxide piezoresistor sheet and two is in series ₂O ₃-Sb ₂O ₃It is the high-pressure type zinc oxide varistor; The two ends of the described two high-pressure type zinc oxide varistors that are in series are electrically connected with the two ends of described high energy type zinc oxide piezoresistor sheet respectively; And lead to from the points of common connection of two kinds of piezoresistive wafers and to be used for the splicing ear that is electrically connected with semiconductor variable flow device DC side, lead to from the points of common connection of the two high-pressure type zinc oxide varistors that are in series and be used for the splicing ear that is electrically connected with the earth.

In the execution mode to the further optimization of technique scheme, described high energy type zinc oxide piezoresistor sheet is by one or one group of ZnO-Bi forming through serial or parallel connection ₂O ₃-TiO ₂Be that piezo-resistance is formed; Described two high-pressure type zinc oxide varistors are by two or two groups of ZnO-Bi forming through serial or parallel connection ₂O ₃-Sb ₂O ₃Be that piezo-resistance is formed.

The present invention also provides the technical scheme with first kind of compound overvoltage protection device application in the semiconductor variable flow device; It adopts three groups of described overvoltage protectors; Wherein, Described three high energy type zinc oxide piezoresistor sheets are connected with the mode of " Δ " wiring exchanges the inlet wire side with the semiconductor variable flow device three phase lines, are used to suppress switching overvoltage; Described three high-pressure type zinc oxide varistors are connected with the mode of " Y " wiring exchanges the inlet wire side with the semiconductor variable flow device three phase lines; The central point of " Y " wiring is connected with the earth, is used to suppress the phase line of unsteady flow inlet wire side and the Lightning Over-voltage between the earth.

The present invention also provides the technical scheme with second kind of compound overvoltage protection device application in the semiconductor variable flow device; It adopts one group of described overvoltage protector; Wherein, The two ends of described high energy type zinc oxide piezoresistor sheet are connected with the two ends of convertor equipment DC side or unsteady flow outlet side respectively, are used to suppress switching overvoltage; The end that described two high-pressure type zinc oxide varistors are connected with described high energy type zinc oxide piezoresistor sheet also is connected with the two ends of convertor equipment DC side or unsteady flow outlet side respectively; The public connecting end of two high-pressure type zinc oxide varistors is connected with the earth, is used to suppress Lightning Over-voltage.

The present invention also provides a kind of technical scheme of compound overvoltage protection device; It comprises the grounding screw rod that is positioned at the center, second battery lead plate, high-pressure type zinc oxide varistor, first battery lead plate, high energy type zinc oxide piezoresistor sheet, the third electrode plate that is socketed on the described grounding screw rod successively from top to bottom and is electrically connected; Be provided with insulating barrier between described grounding screw rod outer wall and socket each battery lead plate and piezoresistive wafer inwall above that, described first battery lead plate, third electrode plate are provided with and are used for the wiring screw rod that is electrically connected with semiconductor variable flow device unsteady flow input side.

In the further execution mode of optimizing of technique scheme; Be positioned on the described grounding screw rod second battery lead plate above also be socketed with the 4th battery lead plate that is connected with described first battery lead plate through a wiring screw rod wherein; Be provided with insulation crust between described the 4th battery lead plate and the third electrode plate; Described second battery lead plate, high-pressure type zinc oxide varistor, first battery lead plate, high energy type zinc oxide piezoresistor sheet all are positioned at insulation crust, and are provided with insulating plug between described the 4th battery lead plate and third electrode plate and the described grounding screw rod.

More optimally, the two ends of described grounding screw rod and described wiring screw rod are arranged on the 4th battery lead plate and the third electrode plate outside with exposing.

The present invention also provides the technical scheme of another kind of compound overvoltage protection device; It comprises the grounding screw rod that is positioned at the center, is socketed in the high energy type zinc oxide piezoresistor sheet on the described grounding screw rod, second battery lead plate, high-pressure type zinc oxide varistor, first battery lead plate that is socketed on the described grounding screw rod and is arranged on described high energy type zinc oxide piezoresistor sheet two ends symmetrically and is electrically connected successively; Be provided with insulating barrier between described grounding screw rod outer wall and socket each battery lead plate and piezoresistive wafer inwall above that, described each first battery lead plate is provided with and is used for the wiring screw rod that is electrically connected with semiconductor variable flow device DC side or unsteady flow outlet side.

In the further execution mode of optimizing of technique scheme; On described grounding screw rod, also be arranged with the third electrode plate that is connected with described first battery lead plate through wiring screw rod respectively; Between two third electrode plates, also be provided with insulation crust; Described high energy type zinc oxide piezoresistor sheet, second battery lead plate, high-pressure type zinc oxide varistor and first battery lead plate all are positioned at insulation crust, are provided with insulating plug between described two third electrode plates and the described grounding screw rod.

More optimally, the two ends of described grounding screw rod and wiring screw rod are arranged on the outside of two ends third electrode plate with exposing.

The present invention has following advantage: the invention provides the two different overvoltage protectors that two specific character different oxidation zinc piezo-resistances are joined together to form; And having provided two kinds of overvoltage protectors respectively uses in the semiconductor variable flow device; When correspondingly overvoltage protector is linked in semiconductor variable flow device interchange input side or the DC side/outlet side, not only can suppresses switching overvoltage, and can suppress Lightning Over-voltage; Simple in structure, be easy to realize.

Description of drawings

Accompanying drawing 1 is the scheme of various overvoltage protections used in the prior art;

Accompanying drawing 2 is the electrical schematic diagram that lightning strike accident is analyzed in the thyristor rectifier in the prior art;

Accompanying drawing 3 is the circuit theory diagrams of a kind of overvoltage protector (VPA) that technical scheme is implemented according to the present invention;

Accompanying drawing 4 is the circuit theory diagrams of the another kind of overvoltage protector (VPB) that technical scheme is implemented according to the present invention;

Accompanying drawing 5 is for being applied in the circuit connection sketch map in the semiconductor variable flow device with VPA among Fig. 3 and VPB shown in Figure 4;

Accompanying drawing 6 is the structural representation of a kind of over-pressure safety device (VPA) that technical scheme is implemented according to the present invention;

Accompanying drawing 7 is the structural representation of the another kind of over-pressure safety device (VPB) that technical scheme is implemented according to the present invention;

Wherein: 1, high-pressure type zinc oxide varistor; 2, high energy type zinc oxide piezoresistor sheet; 3, third electrode plate; 4, the 4th battery lead plate; 5, second battery lead plate; 6, first battery lead plate; 8, grounding screw rod; 9, nut; 10, insulating barrier; 11, wiring screw rod; 12, wiring screw rod; 13, insulation crust; 14, insulating plug; 15, nut;

1 ', high-pressure type zinc oxide varistor; 2 ', high energy type zinc oxide piezoresistor sheet; 3 ', third electrode plate; 5 ', second battery lead plate; 6 ', first battery lead plate; 8 ', grounding screw rod; 9 ', nut; 10 ', insulating barrier; 11 ', wiring screw rod; 13 ', insulation crust; 14 ', insulating plug; 15 ', nut.

Embodiment

Do further detailed explanation below in conjunction with the accompanying drawing specific embodiments of the invention:

A kind of overvoltage protector shown in Figure 3, code name represent with VPA, and it comprises one or one group of ZnO-Bi forming through serial or parallel connection ₂O ₃-TiO ₂Be high energy type zinc oxide piezoresistor sheet VE and one or one group of ZnO-Bi forming through serial or parallel connection ₂O ₃-Sb ₂O ₃Be high-pressure type zinc oxide varistor VH, wherein, the end of high-pressure type zinc oxide varistor VH and the end of high energy type zinc oxide piezoresistor VE are electrically connected, and form the common exit 1 that connects, and the other end of VH and VE is respectively exit 2 and 3.This overvoltage protector VPA is used for the overvoltage protection that the semiconductor variable flow device exchanges input side; Mode of connection is as shown in Figure 5; Particularly; Three high energy type zinc oxide piezoresistor sheet VE among this protector VPA link to each other with Δ connection and the A that exchanges the inlet wire side, B, three phase lines of C, from the switching overvoltage of transformer, and absorb the magnetic field energy in excitatory reactance of transformer master and the leakage reactance simultaneously when being responsible for suppressing the operation of folding lock; Three (group) high-pressure type zinc oxide varistor VH among the protector VPA link to each other with the A that exchanges the inlet wire side, B, three phase lines of C respectively with the Y connection; The central point of " Y " wiring is connected with the earth; Be responsible for to suppress exchange the phase line of inlet wire side and the Lightning Over-voltage between the earth, and the excessive charge on the phase line is released in the earth.

Shown in Figure 4 is another kind of overvoltage protector provided by the invention, and code name is VPB, and this protector VPB comprises one or one group of ZnO-Bi forming through serial or parallel connection ₂O ₃-TiO ₂Be high energy type zinc oxide piezoresistor sheet VE and two or two groups of ZnO-Bi forming through serial or parallel connection ₂O ₃-Sb ₂O ₃Be high-pressure type zinc oxide varistor VH; Wherein, Two groups of high-pressure type zinc oxide varistor VH are cascaded; And draw splicing ear 3 from its public junction, and the other end separately of these two groups of high-pressure type Zinc-oxide piezoresistors is electrically connected with the two ends of high energy type zinc oxide piezoresistor VE respectively again, thereby draws splicing ear 1 and 2 respectively.This overvoltage protector VPB can be used for the overvoltage protection of semiconductor variable flow device DC side or unsteady flow outlet side; Mode of connection is as shown in Figure 5; The two ends of described high energy type zinc oxide piezoresistor sheet VE link to each other with the two ends of equipment DC side or unsteady flow outlet side respectively; Switching overvoltage when being responsible for suppressing the inductive load disconnection, and absorb operation surge energy simultaneously from inductive load.The end of described two (group) high-pressure type zinc oxide varistor VH links to each other with the two ends of equipment DC side or unsteady flow outlet side respectively; The other end links to each other with the earth jointly; Be responsible for suppression equipment DC side or unsteady flow outlet side Lightning Over-voltage that directly suffer or that sense, and will export excessive charge on the cable and release in the earth.

To the Mathematical Modeling and the operation principle of each overvoltage protector be described below below:

1, the type selection calculation method of VE is following among the VPA:

A, specified pressure sensitive voltage are promptly protected the type selection calculation formula of operation voltage:

$\frac{1.49U_{21}(1+r_M)}{S_{\mathrm{MA}}}\&le;{\mathrm{<figure-callout\; id="10"\; label="U"\; filenames="H2009100542964E00032.png,H2009100542964E00041.png"\; state="\{\{state\}\}">U</figure-callout>}}_{10\mathrm{mA}}<\frac{U_M-R_{\mathrm{GM}}{I}_M}{1.05{\left(100I_M\right)}^{1/{\mathrm{\&alpha;}}_{\min }}}---\left(3\right)$

In the formula:

U _10mA: the specified pressure sensitive voltage of high energy type piezo-resistance (allowing manufacture deviation ± 5% o'clock), unit: V in maximum;

U ₂₁: the rated line voltage effective value of supply transformer secondary, unit: V;

r _M: net side maximum voltage regulation;

S _MA: the maximum of the high energy type piezo-resistance of being selected for use exchanges chargeability (by manufacturer's regulation);

U _M: the off-state (forward) of being protected power semiconductor device is repetitive peak voltage (U not _Dsm) or non-repetitive peak reverse voltage (U _Rsm), get the minimum value among both, unit: V;

R _GM: the maximum equivalent grain resistance of the high energy type piezo-resistance of being selected for use (by manufacturer's regulation);

I _M: when the supply transformer zero load is operated a switch, flow through the maximum current (need according to the calculation of parameter of supply transformer) of high energy type piezo-resistance; Unit: A;

α _Min: the minimum non linear coefficient of the high energy type piezo-resistance of being selected for use (by manufacturer's regulation).

The type selection calculation formula of B, nominal energy capacity:

$E_M\&GreaterEqual;\frac{{2S}_N}{\mathrm{\&pi;f}}\left(\frac{I_0}{I_N}\right)+K_{\mathrm{dg}}^2\frac{{\mathrm{<figure-callout\; id="2"\; label="S\; N\; e"\; filenames="H2009100542964E00032.png,H2009100542964E00041.png"\; state="\{\{state\}\}">S</figure-callout>}}_{N}e}{2\mathrm{\&pi;f}}---\left(4\right)$

In the formula:

E _M: the nominal energy capacity of high energy type piezo-resistance, unit: kJ;

S _N: the specified apparent power of supply transformer, unit: kVA;

F: mains frequency, unit: Hz;

The no-load current ratio of

supply transformer;

K _Dg: protected the maximum of power semiconductor device to allow the overcurrent multiple;

E: the short-circuit voltage ratio of supply transformer.

2, the type selection calculation method of VE is following among the described VPB:

VE's is identical among A, specified pressure sensitive voltage and the VPA;

The type selection calculation formula of B, nominal energy capacity:

Load at convertor equipment is under the situation of DC motor:

$E_M\&GreaterEqual;7.89{\mathrm{CK}}_{\mathrm{dg}}^2\left(\frac{S_N}{p\&CenterDot;n}\right)\cos \mathrm{\&theta;}---\left(5\right)$

In the formula:

P: the number of pole-pairs of direct current machine;

N: the rated speed of direct current machine, unit: r/min;

θ: the triggering pilot angle the when output voltage of convertor equipment equals the direct current machine rated voltage, unit: degree;

C: coefficient, it is 0.1 that small electromotor is arranged, non-compensated machine is 0.4;

The definition of all the other symbols is the same.

Load at convertor equipment is under the situation of other type inductive load, should press following formula according to its equivalent electric circuit and select E _MValue:

$E_M\&GreaterEqual;3(\frac{1}{2}L\&CenterDot;i_{\max }^2)---\left(6\right)$

In the formula, L: the equivalent energy storage inductor in the load, unit: H;

i _Max: the maximum current peak that flows through among the L, unit: A.

VH among said VPA and the VPB is at nominal lightning discharge electric current (I _n) under deboost U _ClnShould meet the following conditions:

U _cln＜(1+R _MI/R _SM)U _M (7)

In the formula:

U _Cln: the deboost of high-pressure type piezo-resistance under nominal lightning discharge electric current.Unit: V;

R _MI: convertor equipment exchanges input side or the minimum permissible value of outlet side insulation against ground resistance, unit: k Ω;

R _SM: protected the power semiconductor device forward to apply not repetitive peak voltage (U of off-state (forward) _Dsm) time resistance value or oppositely apply not repetitive peak voltage (U _Rsm) time resistance value, get the maximum among both, unit: k Ω;

Technical parameters such as the nominal maximum discharge current of VH, nominal discharge current should be confirmed according to the concrete laying state of the on-the-spot geographical conditions of semiconductor variable flow equipment work, meteorological condition, distribution system and with reference to the relevant technologies standard among said VPA and the VPB.

R in the formula 7 _MIConfirm and special monitoring, alarming equipment should be installed by the manufacturer of convertor equipment or user.Under the situation that does not have monitoring, alarming equipment by R _MI=0 considers.

Described VPA and VPB are when absorbing switching overvoltage, if the action simultaneously of VH wherein can cause the disastrous accident on fire from explosion of Denging.For avoiding the generation of this situation, the specified pressure sensitive voltage U of VH _1mAMust greater than (U _10mASpecified pressure sensitive voltage for VE among same VPA or the VPB), U _1mAConcrete choosing value, should under the prerequisite that satisfies formula 7, take all factors into consideration VH and the VA characteristic curve of VE, the operational factor of convertor equipment and the factors such as intrinsic manufacture deviation of piezo-resistance selected for use, confirm through Computer Simulation or analogue test.

Described VPA and VPB if the lightning current that VE wherein flows through is excessive, can cause the slump of disastrous proportions of its pressure sensitive voltage when absorbing Lightning Over-voltage.For avoiding the generation of this situation; The non linear coefficient of the high energy type piezo-resistance of being selected for use should be lower than the non linear coefficient of the high-pressure type piezo-resistance of being selected for use, and the grain resistance of the high energy type piezo-resistance of being selected for use simultaneously should be higher than the grain resistance of the high-pressure type piezo-resistance of being selected for use.The concrete parameter of selecting for use is not more than at the lightning current peak value that actual flow is crossed VE under the precondition of nominal lightning discharge electric current of the high energy type piezo-resistance of being selected for use, confirms through Computer Simulation or analogue test.

The structural representation of the VPA that implements according to the present invention shown in Figure 6; It comprises the grounding screw rod 8 that is positioned at the center, be socketed on the grounding screw rod 8 successively from top to bottom and second battery lead plate 5 that is electrically connected, high-pressure type zinc oxide varistor 1, first battery lead plate 6, high energy type zinc oxide piezoresistor sheet 2, third electrode plate 3; Be provided with insulating barrier 10 between described grounding screw rod 8 outer walls and socket each battery lead plate and piezoresistive wafer inwall above that; For preventing to be short-circuited through third electrode plate 3 between grounding screw rod 8 and the wiring screw rod 12; Between third electrode plate 3 and grounding screw rod 8, be provided with insulating plug 14; In the present embodiment; Second battery lead plate 5, high-pressure type zinc oxide varistor 1, first battery lead plate 6, high energy type zinc oxide piezoresistor sheet 2 and third electrode plate 3 are provided with up and down with being adjacent to, and are provided with nut 9 in the outside of second battery lead plate 5 and third electrode plate 3, thereby above-mentioned battery lead plate and piezoresistive wafer are fixed on the grounding screw rod 8.

On second battery lead plate 5 and third electrode plate 3, also be provided with wiring screw rod 11,12, at least one end of wiring screw rod 11,12 and grounding screw rod 8 forms three leading-out terminals among the VPA shown in Figure 3 respectively like this.

In order to make this over-pressure safety device have the good insulation performance effect; To strengthen its applicability; Be positioned on the grounding screw rod 8 second battery lead plate 5 above and also be arranged with the 4th electrode 4 with second battery lead plate, 5 places of keeping at a certain distance away; The 4th electrode 4 laterally arranges with the third electrode 3 that is positioned at bottom; And its lateral dimension simultaneously, is provided with insulation crust 13 greater than the lateral dimension of second battery lead plate 5, first battery lead plate 6 and two kind of piezoresistive wafer between the 4th battery lead plate 4 and third electrode plate 3; Like this, second battery lead plate 5, first battery lead plate 6 and two kind of piezoresistive wafer 1,2 all are arranged in insulation crust 13 and the 4th battery lead plate 4, the third electrode plate 3 formed spaces.

Wiring for ease; Wiring screw rod 11 is arranged on the outside of the 4th battery lead plate 4 with passing; Simultaneously; For preventing to be short-circuited through the 4th battery lead plate 4 between grounding screw rod 8 and the wiring screw rod 11, between the 4th battery lead plate 4 and grounding screw rod 8, be provided with insulating plug 14, the fixing of above-mentioned the 4th battery lead plate 4, insulation crust 13 realized through the nut 15 that is connected with grounding screw rod 8.

Connect ground wire nearby in order to further facilitate, in the present embodiment, the outside that is arranged on the 4th battery lead plate 4 and third electrode plate 3 that expose respectively at the two ends of grounding screw rod 8.

Shown in Figure 7 is the structural representation of the VPB of enforcement according to the present invention; It comprises grounding screw rod 8 ', is socketed in the third electrode plate 3 ' at the two ends of grounding screw rod 8 ' respectively; Between two third electrode plates 3 ', be provided with insulation crust 13 '; Simultaneously, be fixed on the grounding screw rod 8 ' through nut 15 ' being provided with between each third electrode plate 3 ' and the grounding screw rod 8 ' between insulating plug 14 ', two third electrode plates 3 ' and the insulation crust 13 '; And, between two third electrode plates 3 ' and insulation crust 13 ', be formed with a containing cavity.Comprise the high energy type zinc oxide piezoresistor sheet 2 ' that is socketed on the grounding screw rod 8 ' in this containing cavity; First battery lead plate 6 ' that is provided with second battery lead plate 5 ', high-pressure type zinc oxide varistor 1 ' symmetrically and is connected at the upper and lower side of high energy type zinc oxide piezoresistor sheet 2 ' with high energy type zinc oxide piezoresistor sheet 2 '; Be electrically connected between described each battery lead plate and the piezoresistive wafer; Two ends are fixed and are arranged on the grounding screw rod 8 ' with being adjacent to through nut 9 '; In order to make insulation between each battery lead plate, piezoresistive wafer and the grounding screw rod 8 ', be provided with insulating barrier 10 ' at each battery lead plate, piezoresistive wafer inwall and grounding screw rod 8 ' socket place.

On two first battery lead plates 6 ', be respectively arranged with wiring screw rod 11 ', the wiring screw rod 11 ' of side is passed third electrode plate 3 ' and is arranged on its outside with exposing, to be used for binding post.

Connect ground wire nearby in order to further facilitate equally, in the present embodiment, the outside that is arranged on two third electrode plates 3 ' that expose respectively at the two ends of grounding screw rod 8 '.

Above-mentioned combination embodiment is illustrated technical conceive of the present invention and characteristics; But above-mentioned explanation can not be interpreted as the qualification to technical scheme of the present invention; Apparatus structure like two kinds of overvoltage protectors provided by the present invention; Shape like each battery lead plate and piezo-resistance not necessarily adopts circular configuration, and the setting between battery lead plate and the piezo-resistance should not be limited to the mode that is adjacent to that present embodiment provides, and promptly can be carried out the variation of multiple equivalence by embodiment provided by the present invention; In every case the change that the spirit of technical scheme is made according to the present invention all should be encompassed within protection scope of the present invention.

Claims (12)

1. compound overvoltage protection device, it is characterized in that: it comprises ZnO-Bi ₂O ₃-TiO ₂Be high energy type zinc oxide piezoresistor sheet (VE) and ZnO-Bi ₂O ₃-Sb ₂O ₃Be high-pressure type zinc oxide varistor (VH); One end of described high energy type zinc oxide piezoresistor sheet (VE) be connected with an end of high-pressure type zinc oxide varistor (VH) and since then common connection end draw one and be useful on the semiconductor variable flow device and exchange the splicing ear that input side is electrically connected; Lead to from the other end of described high energy type zinc oxide piezoresistor sheet (VE) and to be used for exchanging another splicing ear that input side is electrically connected, draw one from the other end of described high-pressure type zinc oxide varistor (VH) and be useful on the splicing ear that is electrically connected with the earth with the semiconductor variable flow device.

2. compound overvoltage protection device according to claim 1 is characterized in that: described high energy type zinc oxide piezoresistor sheet (VE) is by a ZnO-Bi ₂O ₃-TiO ₂Be piezo-resistance or one group of ZnO-Bi forming through serial or parallel connection ₂O ₃-TiO ₂Be that piezo-resistance constitutes; Described high-pressure type zinc oxide varistor (VH) is by a ZnO-Bi ₂O ₃-Sb ₂O ₃Be piezo-resistance or one group of ZnO-Bi forming through serial or parallel connection ₂O ₃-Sb ₂O ₃Be that piezo-resistance constitutes.

3. compound overvoltage protection device, it is characterized in that: it comprises a ZnO-Bi ₂O ₃-TiO ₂Be that the ZnO-Bi2O3-Sb2O3 that high energy type zinc oxide piezoresistor sheet (VE) and two is in series is high-pressure type zinc oxide varistor (VH); The two ends of the described two high-pressure type zinc oxide varistors (VH) that are in series are electrically connected with the two ends of described high energy type zinc oxide piezoresistor sheet (VE) respectively; And lead to from the points of common connection of two kinds of piezoresistive wafers and to be used for the splicing ear that is electrically connected with semiconductor variable flow device DC side, lead to from the points of common connection of the two high-pressure type zinc oxide varistors (VH) that are in series and be used for the splicing ear that is electrically connected with the earth.

4. compound overvoltage protection device according to claim 3 is characterized in that: described high energy type zinc oxide piezoresistor sheet (VE) is by one or one group of ZnO-Bi forming through serial or parallel connection ₂O ₃-TiO ₂Be that piezo-resistance is formed; Described two high-pressure type zinc oxide varistors (VH) are by two or two groups of ZnO-Bi forming through serial or parallel connection ₂O ₃-Sb ₂O ₃Be that piezo-resistance is formed.

5. the application process of compound overvoltage protection device according to claim 1 and 2 in the semiconductor variable flow device; It is characterized in that: it adopts three groups of described compound overvoltage protection devices; Wherein, Described three high energy type zinc oxide piezoresistor sheets (VE) are connected with the mode of " △ " wiring exchanges the inlet wire side with the semiconductor variable flow device three phase lines, are used to suppress switching overvoltage; Described three high-pressure type zinc oxide varistors (VH) are connected with the mode of " Y " wiring exchanges the inlet wire side with the semiconductor variable flow device three phase lines; The central point of " Y " wiring is connected with the earth, is used to suppress the phase line of unsteady flow inlet wire side and the Lightning Over-voltage between the earth.

6. according to claim 3 or the application process of 4 described compound overvoltage protection devices in the semiconductor variable flow device; It is characterized in that: adopt one group of described overvoltage protector; Wherein, The two ends of described high energy type zinc oxide piezoresistor sheet (VE) are connected with the two ends of convertor equipment DC side or unsteady flow outlet side respectively, are used to suppress switching overvoltage; The end that described two high-pressure type zinc oxide varistors (VH) are connected with described high energy type zinc oxide piezoresistor sheet (VE) also is connected with the two ends of convertor equipment DC side or unsteady flow outlet side respectively; The public connecting end of two high-pressure type zinc oxide varistors (VH) is connected with the earth, is used to suppress Lightning Over-voltage.

7. compound overvoltage protection device; It is characterized in that: it comprises the grounding screw rod (8) that is positioned at the center, is socketed in second battery lead plate (5), high-pressure type zinc oxide varistor (1), first battery lead plate (6), high energy type zinc oxide piezoresistor sheet (2), the third electrode plate (3) that described grounding screw rod (8) is gone up and is electrically connected successively from top to bottom; Be provided with insulating barrier (10) between described grounding screw rod (8) outer wall and socket each battery lead plate and piezoresistive wafer inwall above that, described first battery lead plate (6), third electrode plate (3) are provided with and are used for exchanging with the semiconductor variable flow device wiring screw rod (11,12) that input side is electrically connected.

8. compound overvoltage protection device according to claim 7; It is characterized in that: the top that on described grounding screw rod (8), is positioned at second battery lead plate (5) also is socketed with the 4th battery lead plate (4) that is connected with described first battery lead plate (6) through a wiring screw rod (11) wherein; Be provided with insulation crust (13) between described the 4th battery lead plate (4) and the third electrode plate (3); Described second battery lead plate (5), high-pressure type zinc oxide varistor (1), first battery lead plate (6), high energy type zinc oxide piezoresistor sheet (2) all are positioned at insulation crust (13), and are provided with insulating plug (14) between described the 4th battery lead plate (4) and third electrode plate (3) and the described grounding screw rod (8).

9. compound overvoltage protection device according to claim 8 is characterized in that: the two ends of described grounding screw rod (8) and described wiring screw rod (11,12) are arranged on the 4th battery lead plate (4) and third electrode plate (3) outside with exposing.

10. compound overvoltage protection device; It is characterized in that: it comprises the grounding screw rod (8 ') that is positioned at the center, be socketed in high energy type zinc oxide piezoresistor sheet (2 ') on the described grounding screw rod (8 '), be socketed in second battery lead plate (5 '), high-pressure type zinc oxide varistor (1 '), first battery lead plate (6 ') that described grounding screw rod (8 ') was gone up and was arranged on symmetrically described high energy type zinc oxide piezoresistor sheet (2 ') two ends and is electrically connected successively; Be provided with insulating barrier (10 ') between described grounding screw rod (8 ') outer wall and socket each battery lead plate and piezoresistive wafer inwall above that, described each first battery lead plate (6 ') is provided with and is used for semiconductor variable flow device DC side or exchanges the wiring screw rod (11 ') that outlet side is electrically connected.

11. compound overvoltage protection device according to claim 10; It is characterized in that: on described grounding screw rod (8 '), also be arranged with the third electrode plate (3 ') that is connected with described first battery lead plate (6 ') through wiring screw rod (11 ') respectively; Between two third electrode plates (3 '), also be provided with insulation crust (13 '); Described high energy type zinc oxide piezoresistor sheet (2 '), second battery lead plate (5 '), high-pressure type zinc oxide varistor (1 ') and first battery lead plate (6 ') all are positioned at insulation crust (13 '), are provided with insulating plug (14 ') between described two third electrode plates (3 ') and the described grounding screw rod (8 ').

12. compound overvoltage protection device according to claim 11 is characterized in that: the two ends of described grounding screw rod (8 ') and wiring screw rod (11 ') are arranged on the outside of two ends third electrode plates (3 ') with exposing.

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