CN201975764U

CN201975764U - Frequency converter load short circuit protection circuit for centrifugal machine

Info

Publication number: CN201975764U
Application number: CN 201020178833
Authority: CN
Inventors: 谢昌树
Original assignee: Shanghai Lishen Scientific Equipment Co Ltd
Current assignee: Shanghai Lishen Scientific Equipment Co Ltd
Priority date: 2010-04-28
Filing date: 2010-04-28
Publication date: 2011-09-14
Anticipated expiration: 2020-04-28

Abstract

The utility model discloses a frequency converter load short circuit protection circuit for a centrifugal machine, which comprises an IGBT (insulated gate bipolar transistor, Q1), a drive and soft turn off output circuit and a short-circuit protection circuit, wherein the collecting electrode of the IGBT (Q1) is connected with the cathode of a fast recovery diode (D1), the anode of the diode (D1) is used for voltage parting through resistors (R1 and R2), a triode (Q2) is enabled to conduct through the diode (D2), the grid voltage of the IGBT is limited and reduced through reverse connection of voltage stabilizing tubes (D4 and D5), meanwhile, a triode (Q3) is enabled to conduct through the delay of a resistor (R3) and a capacitor (C1), soft turn off signals are sent, and the emitting electrode of the IGBT (Q1) is connected in series with a sampling resistor (R5) for detecting short circuit current; and on the other hand, in case of short circuit, the sampling resistor (R5) is used for detecting short circuit current, high level output by a comparator enables (Q2) to conduct to lower grid voltage, the triode (Q3) is enabled to conduct through the delay of the resistor (R3) and the capacitor (C1), and grid soft turn off is carried out for protecting an inverter circuit.

Description

A kind of centrifuge protective circuit of inverter load short circuit

Technical field

The utility model relates to IGBT (igbt; Insulated Gate Bipolar Transistor) protective circuit, be specifically related to a kind of be applied in centrifuge with in the equipment such as frequency converter, Switching Power Supply as the IGBT of the device for power switching protective circuit when the load short circuits.

Background technology

When the IGBT power tube of the frequency converter of centrifuge during in work, bigger when running into the overcurrent multiple suddenly, when load short circuits or bridge arm direct pass fault especially take place, very big in instantaneous shutoff grid impulse meeting because of di/dt, in the stray inductance of loop, respond to very high due to voltage spikes and IGBT is damaged, for this reason, should make grid impulse voltage soft shutoff in 2-5us drop to no-voltage.And some IGBT driver has soft turn-off function; but can not thoroughly turn-off; if do not take measures, can cause the soft turn-off protection of each cycle IGBT driver once under the situation that does not have to eliminate at the short trouble state, the heat accumulation of Chan Shenging can cause IGBT to damage like this.

The utility model content

Protective circuit when technical problem to be solved in the utility model is to provide at the deficiencies in the prior art a kind of IGBT of being used for load short circuits can thoroughly be turn-offed the grid voltage of IGBT power tube at short notice.

In order to realize the foregoing invention purpose, the technical solution adopted in the utility model is as follows:

A kind of centrifuge protective circuit of inverter load short circuit; comprise IGBT; drive and soft shutoff output circuit and short-circuit protection circuit; the collector electrode of IGBT (Q1) connects the negative electrode of fast recovery diode (D1); the anode of this diode (D1) is by resistance (R1; R2) dividing potential drop; make triode (Q2) conducting through diode (D2); the IGBT grid voltage is by voltage-stabiliser tube (D4; D5) oppositely connection limits and step-down; simultaneously through resistance (R3); electric capacity (C1) postpones to make triode (Q3) conducting; send to soft cut-off signals, sampling resistor (R5) that detects short circuit current of described IGBT (Q1) emitter serial connection.

Further be characterized as, described short-circuit protection circuit comprises that one can detect the comparator of short-circuit voltage.

And described triode IGBT (Q1) and triode (Q2) are NPN transistor.

Advantage of the present utility model is: when load short circuits or bridge arm direct pass fault take place IGBT, can pass through sampled I GBT collector voltage and short-circuit detecting duplicate protection inverter circuit, the grid voltage of thorough soft shutoff IGBT prevents the damage of IGBT.

Description of drawings

Fig. 1 is a circuit structure diagram of the present utility model.

Embodiment

For technological means, creation characteristic that the utility model is realized, reach purpose and effect is easy to understand, below in conjunction with concrete diagram, further set forth the utility model.

As shown in Figure 1, the protective circuit when being used for centrifuge with the inverter load short circuit comprises IGBT Q1, driving and soft shutoff output circuit 1, short-circuit protection circuit 2, transistor seconds Q2 and the 3rd transistor Q3; During load short circuits, when (or IGBT is because of other fault overcurrent), the Vce of IGBT Q1 increases, triode Q2 gate drive current warp, resistance R 1, R2 dividing potential drop, make triode Q2 conducting through diode D2, the IGBT grid voltage by voltage-stabiliser tube D4, D5 oppositely connect limit and step-down, restriction IGBT peak current magnitude postpones to make triode Q3 conducting through resistance R 3, capacitor C 1 simultaneously, send to soft cut-off signals, turn-off the grid impulse input; On the other hand, detect short circuit current through current sampling resistor R5 when short circuit, the high level of exporting through comparator makes the Q2 conducting fall grid voltage, postpones to make triode Q3 conducting through resistance R 3, capacitor C 1 simultaneously, carries out the soft shutoff of grid, protects inverter circuit.

Operation principle of the present utility model is as follows:

Be to utilize IGBT Q1 when load short circuits; collector voltage is detected; the general protective circuit that the electric current of emitter is detected; the circuit working principle is: during load short circuits (or IGBT is because of other fault overcurrent); the Vce of IGBT Q1 increases; transistor seconds Q2 gate drive current is through R1; the R2 dividing potential drop makes transistor seconds Q2 conducting; IGBT Q1 grid voltage is limited and step-down by the first voltage-stabiliser tube D4 and the second voltage-stabiliser tube D5; restriction IGBT Q1 peak current magnitude; postpone to make the 3rd transistor Q3 conducting through delay circuit 3 simultaneously; make driving and soft shutoff output circuit 1 send to the grid of soft cut-off signals to IGBTQ1; simultaneously; emitter at IGBT Q1 when load short circuits is connected in series one the 5th resistance R 5; because the voltage (being sampled voltage) and the electric current of this series resistance of flowing through at the resistance two ends of this series connection are directly proportional: (I is the current value of this series resistance of flowing through to U=IR; R is the resistance value of this series connection; U is the magnitude of voltage at this series resistance R two ends; be sampled voltage), therefore the magnitude of voltage that obtains just can be used as the sampled value of electric current.Compare through the sample voltage value of the 5th resistance R 5 detection gained and the reference voltage level of the voltage comparator in the short-circuit protection circuit 2 so; the signal of its output output is the overcurrent index signal; promptly being output as high level makes the Q2 conducting fall the grid voltage of IGBT Q1; and make the

3rd resistance R

3 and 1 time-delay of first capacitor C make the 3rd transistor Q3 conducting simultaneously; controlling and driving and soft shutoff output circuit 1 are sent to the grid of soft cut-off signals to IGBT Q1, thereby thoroughly turn-off grid output.

More than show and described basic principle of the present utility model and principal character and advantage of the present utility model.The technical staff of the industry should understand; the utility model is not restricted to the described embodiments; that describes in the foregoing description and the specification just illustrates principle of the present utility model; under the prerequisite that does not break away from the utility model spirit and scope; the utility model also has various changes and modifications; these changes and improvements all fall in claimed the utility model scope, and the claimed scope of the utility model is defined by appending claims and equivalent thereof.

Claims

1. a centrifuge is with the protective circuit of inverter load short circuit; comprise IGBT Q1; drive and soft shutoff output circuit and short-circuit protection circuit; it is characterized in that; the collector electrode of IGBT Q1 connects the negative electrode of fast recovery diode D1; the anode of this diode D1 is by resistance R 1; the R2 dividing potential drop; make triode Q2 conducting through diode D2; the IGBT grid voltage is by voltage-stabiliser tube D4; D5 oppositely connect limit and step-down; simultaneously through resistance R 3; capacitor C 1 postpones to make triode Q3 conducting; send to soft cut-off signals, sampling resistor R5 who detects short circuit current of described IGBT Q1 emitter serial connection.

2. a kind of centrifuge according to claim 1 is characterized in that with the protective circuit of inverter load short circuit described short-circuit protection circuit comprises that one can detect the comparator of short-circuit voltage.

3. a kind of centrifuge according to claim 1 is characterized in that with the protective circuit of inverter load short circuit described triode Q1 and Q2 are NPN transistor.