CN205004741U - Two -way bridge type switch short -circuit fault current limiter based on a single IGBT - Google Patents

Abstract

The utility model provides a two -way bridge type switch short -circuit fault current limiter based on a single IGBT, including alternating current power supply, two -way bridge type switch current limiter and load. Wherein, two -way bridge type switch current limiter includes piezo -resistor, resistance R2, inductance L2 and the two -way current limiting switch of H bridge type, after resistance R2 and inductance L2 establish ties, forms parallelly connected structure with piezo -resistor and two -way current limiting switch, two -way current limiting switch includes that five diodes, IGBT manage K, electric capacity and inductance L1, diode D1's anodal negative pole with D3 is connected to the one end of power, and the collecting electrode that IGBT managed K is received with D2's negative pole jointly to diode D1's negative pole, and electric capacity and IGBT pipe K are parallelly connected, and IGBT pipe K's projecting pole is continuous with diode D's negative pole, and D3 and D4's positive pole is received to diode D's positive pole, and inductance L1 and diode D are parallelly connected, and diode D2's negative pole anodal and D4 is connected to the load. The utility model discloses a hardware circuit simple structure, the phenomenon of improving the branch current burr that can be better.

Description

Based on the bidirectional bridge type switch short fault current limiter of single IGBT

Technical field

The utility model relates to a kind of short-circuit fault current limiter based on single IGBT bidirectional bridge type switch, belongs to power technique fields.

Background technology

In electric power system, because grid short circuit is common a kind of fault, the harm caused is very huge, how by grid short circuit current limit within a rational scope, become a vital task of current power network design.The method of up-to-date employing installs fault current limiter additional at sensitive position.Fault current limiter, in principle, can adopt various different device and topological structure.Such as have, series connection L-C resonant mode fault current limiter, the series fault flow restricter of two IGBT switch, saturation transformer coupled mode fault current limiter and the bridge type FCL etc. containing self-turn-off device.Different devices and structures shape they have different application and feature.

As can be seen here, a rational short-circuit fault current limiter is designed most important.The most frequently used structure is tandem type flow restricter, and the switch in current current limliting bridge is unidirectional mostly, and control not to be fine to the electric current rate of climb, some is bidirectional switch short circuit current limiter, but what adopt is two IGBT tubular constructions, its control circuit and tactful more complicated, and circuit is when IGBT break-make switches, the burr of branch current is larger.

Summary of the invention

In order to overcome the above problems, the utility model proposes a kind of bidirectional bridge type switch short fault current limiter based on single IGBT, while realizing bidirectional switch, the phenomenon of branch current burr can be improved preferably.

The technical scheme that the utility model adopts is as follows:

Based on the bidirectional bridge type switch short fault current limiter of single IGBT, comprise AC power, bidirectional bridge type switched flow restrictors and load, bidirectional bridge type switched flow restrictors comprises piezo-resistance ZnO, resistance R ₂, inductance L ₂with H bridge type bidirectional current limiting switch, wherein, resistance R ₂and inductance L ₂after series connection, form parallel-connection structure with piezo-resistance ZnO and H bridge type bidirectional current limiting switch, one end of this parallel-connection structure is connected with one end of AC power, and the other end of parallel-connection structure is connected with load; Described H bridge type bidirectional current limiting switch comprises diode D, diode D ₁, diode D ₂, diode D ₃, diode D ₄, IGBT pipe K, electric capacity C and inductance L ₁; Wherein, diode D ₁positive pole and diode D ₃negative pole be connected to one end of AC power, diode D ₁negative pole and diode D ₂negative pole jointly receive the collector electrode of IGBT pipe K, electric capacity C is in parallel with IGBT pipe K, and the emitter of IGBT pipe K is connected with the negative pole of diode D, and the positive pole of diode D receives diode D ₃with diode D ₄positive pole, inductance L ₁in parallel with diode D, diode D ₂positive pole and diode D ₄negative pole be connected to load.

Further, the gate pole of described IGBT pipe K adds pwm pulse signal.

The short-circuit fault current limiter that the utility model provides adopts single IGBT to realize bidirectional switch.By an electric capacity in parallel on IGBT, the phenomenon of branch current burr can be improved preferably, and below IGBT, seal in an inductance can suppress the electric current rate of climb, and add pwm pulse at the gate pole of IGBT, current limitation effect can be changed by the duty ratio changing pwm pulse.Hardware circuit of the present utility model is simple, has high performance-price ratio and high reliability, can extensive use and meet the demand of current electricity market.

Attached caption

Fig. 1 is flow restricter main circuit of the present utility model;

Fig. 2 is the relation between duty ratio and current distributing ratio;

Fig. 3 is the waveform of each branch current under different duty, and (a), (b), (c) figure get duty ratio 20%, 40%, 60% respectively;

Fig. 4 is the impedance angle schematic diagram of the outer branch road of bridge;

Fig. 5 is light-coupled isolation and the full bridge driving circuit figure of utility model;

Fig. 6 (a) is voltage current waveform during pure resistor load, the voltage current waveform that (b) is inductive load;

When Fig. 7 (a) is for pure resistor load, voltage waveform harmonic wave distributes, when (b) is for inductive load, and the harmonic component distribution of voltage waveform;

When Fig. 8 (a) is for pure resistor load, the harmonic wave distribution of electric current, when (b) is for inductive load, the harmonic component distribution of current waveform.

Embodiment

Below in conjunction with accompanying drawing table and example, the utility model is described in further detail.

(1) main circuit design.Bidirectional bridge type switch short fault current limiter circuit diagram of the present utility model as shown in Figure 1.Short-circuit fault current limiter based on single IGBT bidirectional bridge type switch is made up of power supply, bidirectional bridge type switched flow restrictors and load.In the flow restricter shown in Fig. 1, when IGBT device conducting, the impedance that flow restricter presents is approximately zero; When IGBT device by time, current limliting bridge presents high impedance.Therefore, by the switching of control IGBT, can determine whether load current passes through flow restricter.If add pwm pulse at the gate pole of IGBT, and change the duty ratio of pulse signal, the equivalent resistance of such flow restricter just can change, and makes to flow through current-limiting inductance L ₂current value change, just will have metering function flexibly to whole circuit.In circuit shown in Fig. 1, if select 1,2 group of circuit parameter as shown in table 1, then the relation between duty ratio σ and current distributing ratio is as shown in the curve 1,2 in Fig. 2.

Table 1 flow restricter parameter

Sequence number	Internal inductance L 1	Non-essential resistance R 2	External inductors L 2	Electric capacity C	Load resistance R L
						1	10mH	10Ω	10mH	20μH	10Ω
2	10mH	0Ω	10mH	20μH	10Ω

(2) control method and realization.The scheme that the utility model adopts is that whole current-limiting circuit only has a controlled device, when testing circuit has detected open circuit or overcurrent fault, according to the character of fault or the size of short circuit current, carries out sweetly disposition.Bridge circuit can be disconnected, to seal in maximum current-limiting impedance, the short circuit current that restriction is outside larger, all right, adopt one to be similar to the variable-resistance method of parallel equivalent to limit overcurrent or slight short circuit current, realize will lacking fault coverage as far as possible, ensure the object of Electrical Safety.

(3) drive circuit design.Drive circuit comprises optical coupling isolation circuit, full bridge driving circuit two parts.The PWM triggering signal produced by control circuit first receives light-coupled isolation module, after electrical-optical-electricity transforms, be transferred to full-bridge driver module again, and the pwm signal of last output just can be managed by the IGBT directly in circuits for triggering.

The short-circuit fault current limiter based on single IGBT bidirectional bridge type switch that the utility model provides, comprises power supply, bidirectional bridge type switched flow restrictors and load.During normal work; switch closes; the access of flow restricter does not affect the normal power supply of power supply to load; when control circuit detects that load end has overcurrent or open circuit occurs; switch disconnects by control circuit, seals in current-limiting inductance in circuit, and the access due to inductance makes impedance varying circuit large; the short circuit current of load end is just restricted, thus plays a protective role.

1. first build experiment main circuit as shown in Figure 1, form a H bridge type bidirectional current limiting switch with 1 IGBT pipe an electric capacity, 5 diodes and an inductance in parallel, H bridge type bidirectional current limiting switch is in parallel with current-limiting inductance and piezo-resistance ZnO forms flow restricter.

One end of piezo-resistance ZnO is connected with one end of AC power, and the other end is connected with load, resistance R ₂with inductance L ₂series connection, resistance R ₂the other end same one end of receiving power supply the same as piezo-resistance ZnO, inductance L ₂the other end same one end of receiving load the same as piezo-resistance ZnO, diode D ₁positive pole and diode D ₃negative pole same one end of receiving power supply the same as piezo-resistance ZnO, diode D ₁negative pole and D ₂negative pole jointly receive the collector electrode of IGBT pipe K, electric capacity C is in parallel with IGBT pipe K, and the emitter of IGBT pipe K is connected with the negative pole of diode D, and the positive pole of diode D receives diode D ₃with D ₄positive pole, inductance L ₁in parallel with diode D, diode D ₂positive pole and diode D ₄negative pole same one end of jointly receiving load the same as piezo-resistance ZnO.

2. in order to reduce the mutual interference between main circuit and control circuit, guaranteeing system stable operation, needing to add isolation module between control loop and drive circuit.Select opto-coupler chip NEC2501 by control loop and drive circuit isolation in the design.NEC2501 is conventional linear light lotus root, is usually taken as coupled apparatus, has the effect that the superior and the subordinate's circuit is completely isolated, mutually do not have an impact in the functional circuit that various requirement is more accurate, greatly can improve the reliability of operating circuit.That driving chip is selected is the half-bridge driven chip I R2111 that IR company produces, and its inner employing bootstrap technique, can complete the driving task of two switching tubes, decrease the demand of drive circuit to power supply, and have perfect defencive function with a slice IR2111.Chip internal Lookup protocol 650ns Dead Time, can prevent from managing up and down straight-through effectively.Light-coupled isolation of the present utility model and full bridge driving circuit are as shown in Figure 5.

3. the utility model adopts the short-circuit fault current limiter based on single IGBT bidirectional bridge type switch, and the different current limitation effect of driving pulse duty ratio added by IGBT pipe gate pole is also different.As shown in Figure 3, Fig. 3 (a), (b), (c) get duty ratio 20%, 40%, 60% respectively, and three electric currents are load current I respectively _z, flow through the electric current I of current limliting bridge _lwith the electric current I in outside current-limiting inductance _l2.As we can see from the figure, when total load current is constant, the change along with duty ratio is flow through the electric current of flow restricter and is flow through the electric current generation significant change of outside current-limiting inductance, and shunting effect is obvious.If bridge outer series arm RL circuit composition, the mould of branch impedance Z remains unchanged, and changes the phase angle of impedance, as shown in Figure 4, with the outer branch road of Germicidal efficacy bridge to the tapping condition of total load current.When impedance phase angle θ gets 0 °, 10 °, 20 °, 30 °, 50 ° and 70 ° respectively, when the mould value of external load impedance is 10 Ω, the split ratio of the outer branch road of bridge is as shown in table 2, in table

The impact of table Bridge 2 outer branch impedance angle change on split ratio

As seen from Table 2, under same duty ratio, split ratio slightly increases with the increase of impedance angle, and entire change is little, and along with the increase of duty ratio, the outer branch road split ratio of bridge will obviously tail off.This change conforms to predicted value.Therefore, when selecting the impedance parameter of the outer branch road of bridge, main its split ratio of consideration is with the characteristic curve of change in duty cycle.Z in Fig. 4, | Z| and θ is such as formula (1)--shown in (3).

Z＝R+jωL(1)

$\left|Z\right|=\sqrt{R^2+{\left(\mathrm{\ω}L\right)}^2}---\left(2\right)$

$\mathrm{\θ}={\tan }^{-1}\frac{\mathrm{\ω}L}{R}---\left(3\right)$

4. use universal instrument test circuit whether reliably to connect, confirm errorless after, whether normal run signal circuit, detect drive end voltage, reload main circuit power.AC-input voltage Us=220V in the design, frequency 50Hz, bridge-type flow restricter IGBT grid adds pwm pulse, gets duty ratio σ=50%, and with two kinds of dissimilar loads, pure resistor load and inductive load compare.Use the waveform of oscilloscope test circuit key point, and record.Load end output voltage U _zand electric current I _zwaveform as shown in Figure 6.Fig. 6 (a) is voltage current waveform during pure resistor load, and Fig. 6 (b) is voltage current waveform during inductive load.As can be seen from Figure 6, the current waveform smoothness of inductive load is better than the current waveform smoothness of pure resistor load.The pulsation of inductive load both end voltage is greater than pure resistor load.

Carry out fft analysis to the voltage and current waveform of Fig. 6 to obtain, result as shown in Figure 7 and Figure 8.In Fig. 7, when (a) is for pure resistor load, voltage waveform harmonic wave distributes, when (b) is for inductive load, and the harmonic component distribution of voltage waveform.In Fig. 8, when (a) is for pure resistor load, the harmonic wave distribution of electric current, when (b) is for inductive load, the harmonic component distribution of current waveform.During pure resistor load, voltage harmonic aberration rate is 25.39%, and Current harmonic distortion rate is 25.38%; During inductive load, voltage distortion rate is 41%, and current distortion rate is 4.73%.Voltage or current waveform have caused by the switching frequency of this mainly IGBT of a larger harmonic component near 1000Hz, and generally speaking, the proportion wherein shared by harmonic component is also not very big.

Claims (2)

1. based on the bidirectional bridge type switch short fault current limiter of single IGBT, comprise AC power, bidirectional bridge type switched flow restrictors and load, it is characterized in that, bidirectional bridge type switched flow restrictors comprises piezo-resistance ZnO, resistance R ₂, inductance L ₂with H bridge type bidirectional current limiting switch, wherein, resistance R ₂and inductance L ₂after series connection, form parallel-connection structure with piezo-resistance ZnO and H bridge type bidirectional current limiting switch, one end of this parallel-connection structure is connected with one end of AC power, and the other end of parallel-connection structure is connected with load;

Described H bridge type bidirectional current limiting switch comprises diode D, diode D ₁, diode D ₂, diode D ₃, diode D ₄, IGBT pipe K, electric capacity C and inductance L ₁; Wherein, diode D ₁positive pole and diode D ₃negative pole be connected to one end of AC power, diode D ₁negative pole and diode D ₂negative pole jointly receive the collector electrode of IGBT pipe K, electric capacity C is in parallel with IGBT pipe K, and the emitter of IGBT pipe K is connected with the negative pole of diode D, and the positive pole of diode D receives diode D ₃with diode D ₄positive pole, inductance L ₁in parallel with diode D, diode D ₂positive pole and diode D ₄negative pole be connected to load.

2. the bidirectional bridge type switch short fault current limiter based on single IGBT according to claim 1, is characterized in that, the gate pole of described IGBT pipe K adds pwm pulse signal.