Over-current short-circuit protection circuit for power device

Abstract

The utility model discloses a power device overcurrent short circuit protection circuit, which is connected between a power device driving signal circuit and a desaturation detection circuit, and comprises a first divider resistor, a second divider resistor, a first amplitude control resistor and a second amplitude control resistor which are electrically connected in sequence, the first divider resistor is connected with a power device driving signal output end of the chip; a branch of a connection point between the first amplitude control resistor and the second divider resistor is connected to a collector of the power device; a connection point between the first amplitude control resistor and the second amplitude control resistor is used as an input end of the desaturation detection circuit; according to the utility model, on the basis of realizing the desaturation detection circuit, the fine tuning effect of blanking time (namely, the anti-noise time delay can be controlled) is realized at the same time, and the driving structure cost is obviously reduced on the premise of ensuring the driving reliability of the power device without depending on the DESAT function pin of the driving chip.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the field of power electronic structure, concretely relates to a power device overcurrent short circuit protection circuit. BACKGROUND

[0002] IGBT, SiC and other power devices are widely used in industry, automobile and energy industry, such as frequency converter, photovoltaic inverter, vehicle charger, traction inverter and the like. In order to make the system more reliable, these power devices need to have a fast and reliable short circuit protection mechanism, among which, the drive chip desaturation protection (DESAT) is a common short circuit protection measure.

[0003] Specifically, when the power tube is normally working, the current source lcHG inside the drive chip flows out from the DESAT pin, flows through the current-limiting resistor, the reverse diode and the power tube;At this time, since the voltage (VcE) across the CE electrode of the power tube is relatively low, the voltage (VDESAT) of the DESAT pin will be clamped by the VcE voltage and will not be charged to the DESAT threshold voltage (VosTH). When the power tube such as IGBT occurs short circuit, since IGBT exits the saturation region, the VcE voltage will rise rapidly, the reverse diode is blocked, the current source lcHG inside the drive chip charges the capacitor C BLANK ; when the voltage across the capacitor C BLANK exceeds the DESAT threshold voltage (VosTH), the drive chip detects that short circuit occurs and pulls down the drive output to turn off the power device. As can be seen, the drive chip desaturation protection (DESAT) in the prior art is realized by means of the DESAT function pin of the drive chip, which limits the selection of the power tube driving cost and type, and has high cost.

[0004] Therefore, the applicant hopes to find a new technical solution to realize the short circuit protection effect of the power device at low cost. SUMMARY

[0005] Therefore, the utility model discloses the purpose in order to propose a kind of power device overcurrent short circuit protection circuit, realize on the basis of desaturation detection circuit, it is also realized to the fine adjustment effect of blanking time (that is, can control its anti-noise delay), no longer rely on by means of the DESAT function pin of the drive chip, increase operability, improve the range of power device driving scheme selection, ensure the working life of power device, under the premise of guaranteeing the reliability of power device driving, driving structure cost is obviously reduced.

[0006] Therefore, the utility model adopts the technical scheme as follows:

[0007] The application discloses a power device overcurrent short circuit protection circuit, which is connected between a power device driving signal circuit and a desaturation detection circuit, and comprises first and second voltage dividing resistors, first and second amplitude control resistors which are electrically connected in sequence; the first voltage dividing resistor is connected with a power device driving signal output end of a chip; a connection point between the first amplitude control resistor and the second voltage dividing resistor is connected with a collector of the power device through one branch, and the other branch is provided with a transistor between the connection point and the power device driving signal output end of the chip; the second amplitude control resistor is connected with an emitter of the power device; the connection point between the first amplitude control resistor and the second amplitude control resistor serves as an input end of the desaturation detection circuit; and the second voltage dividing resistor is provided with a capacitor in parallel.

[0008] Preferably, the power device driving signal output end of the chip sends a power device driving signal to a gate of the power device.

[0009] Preferably, a third voltage dividing resistor is arranged between the power device driving signal output end of the chip and a collector of the transistor.

[0010] Preferably, a connection point between the first voltage dividing resistor and the second voltage dividing resistor serves as a base input end of the transistor.

[0011] Preferably, an emitter of the transistor is connected with a connection point between the first amplitude control resistor and the second voltage dividing resistor.

[0012] Preferably, the power device driving signal circuit comprises a shunt resistor and a reverse diode; the shunt resistor is connected with the connection point between the first amplitude control resistor and the second voltage dividing resistor, and the reverse diode is connected with the collector of the power device.

[0013] Preferably, the power device driving signal circuit further comprises a charging capacitor, which is connected between the shunt resistor and the emitter of the power device.

[0014] Preferably, the desaturation detection circuit comprises a comparator; the connection point between the first amplitude control resistor and the second amplitude control resistor serves as an input end of the comparator.

[0015] Preferably, the connection point between the first amplitude control resistor and the second amplitude control resistor serves as a positive input end of the comparator, a negative input end of the comparator inputs a preset reference voltage; and an output end of the comparator sends a desaturation detection signal to the chip.

[0016] Preferably, the chip determines the signal level of the power device driving signal output end based on the desaturation detection signal.

[0017] The application sets the specific power device overcurrent short circuit protection circuit composed of discrete components between the power device driving signal circuit and the desaturation detection circuit, realizes the fine adjustment effect of the blanking time (that is, the anti-noise delay can be controlled) on the basis of the desaturation detection circuit through the specific power device overcurrent short circuit protection circuit, no longer relies on the DESAT function pin of the driving chip, increases the operability, improves the range of the power device driving scheme selection, ensures the working life of the power device, obviously reduces the driving structure cost on the premise of ensuring the reliability of the power device driving. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 FIG. 1 is a structural schematic diagram of a power device overcurrent short circuit protection circuit A in the specific embodiment of the application. DETAILED DESCRIPTION

[0019] The embodiment of the utility model discloses a kind of power device overcurrent short circuit protection circuits, connect between power device driving signal circuit and desaturation detection circuit, including sequentially electrically connected first voltage dividing resistor, second voltage dividing resistor, first amplitude control resistance and second amplitude control resistance;First voltage dividing resistor is connected with the power device driving signal output end of chip;The connecting point between first amplitude control resistance and second voltage dividing resistor one branch is connected to the collector of power device, and another branch is equipped with triode between the power device driving signal output end of chip;Second amplitude control resistance is connected with the emitter of power device;The connecting point between first amplitude control resistance and second amplitude control resistance is as the input end of desaturation detection circuit;While second voltage dividing resistor is connected with capacitor in parallel.

[0020] In order to more clearly illustrate the technical scheme in the embodiment of the utility model or prior art, the following will briefly introduce the drawing needed to be used in embodiment or prior art description, obviously, the drawing in the following description is only some embodiments in the utility model, and for those skilled in the art, other drawings can also be obtained according to these drawings without creating labor.

[0021] Please refer to Figure 1 Fig. 1 is a structural schematic diagram of a power device overcurrent short circuit protection circuit A, which is connected between a power device driving signal circuit and a desaturation detection circuit, and includes first voltage dividing resistor R2, second voltage dividing resistor R3, first amplitude control resistance Rs1 and second amplitude control resistance Rs2 connected in sequence; the first voltage dividing resistor R2 is connected with the power device driving signal output end of chip; preferably, in the embodiment, the power device driving signal output end of chip (such as Figure 1The power device driving signal is sent to the gate IGBT-G of the power device (in this embodiment, an IGBT device) from the pin No. 4 of the chip;

[0022] In this embodiment, the connection point between the first amplitude control resistor Rs1 and the second voltage dividing resistor R3 is connected to the collector IGBT-C of the power device, and a triode Q1 is arranged between the other branch and the power device driving signal output end of the chip; preferably, in this embodiment, a third voltage dividing resistor R1 is arranged between the power device driving signal output end of the chip and the collector of the triode Q1; the connection point between the first voltage dividing resistor R2 and the second voltage dividing resistor R3 is the base input end of the triode Q1; the emitter of the triode Q1 is connected to the connection point between the first amplitude control resistor Rs1 and the second voltage dividing resistor R3.

[0023] In this embodiment, the second amplitude control resistor Rs2 is connected to the emitter IGBT-E of the power device; the connection point between the first amplitude control resistor Rs1 and the second amplitude control resistor Rs2 is the input end of the desaturation detection circuit; and the second voltage dividing resistor R3 is connected in parallel with the capacitor C1.

[0024] Preferably, in this embodiment, the power device driving signal circuit comprises a shunt resistor Rlim and a reverse diode D-HV; the shunt resistor Rlim is connected to the connection point between the first amplitude control resistor Rs1 and the second voltage dividing resistor R3, and the reverse diode D-HV is connected to the collector IGBT-C of the power device; the power device driving signal circuit further comprises a charging capacitor Cblk, which is connected between the shunt resistor Rlim and the emitter IGBT-E of the power device.

[0025] Preferably, in this embodiment, the desaturation detection circuit comprises a comparator COMP; the connection point between the first amplitude control resistor Rs1 and the second amplitude control resistor Rs2 is one input end of the comparator COMP; specifically preferably, in this embodiment, the connection point between the first amplitude control resistor Rs1 and the second amplitude control resistor Rs2 is the positive input end 5 of the comparator COMP, the negative input end 6 of the comparator COMP inputs a preset reference voltage REF (the specific voltage value is selected according to actual needs, and in this embodiment, the reference voltage is set to 9V), and the output end 7 of the comparator COMP sends a desaturation detection signal to the chip; the chip determines the signal level of the power device driving signal output end based on the desaturation detection signal, thereby achieving safe and reliable overcurrent short-circuit protection effect of the power device.

[0026] In order to further illustrate the blanking time fine-tuning effect realized by the embodiment (i.e. to control the noise immunity delay thereof), the working principle thereof is further explained as follows, and the working process thereof can be known by those skilled in the art based on the specific embodiment content of the present application, thus it does not serve as the independent innovative content of the present application:

[0027] Firstly, the discharge voltage amplitude is determined through the first amplitude control resistor Rs1 and the second amplitude control resistor Rs2, and then the noise immunity delay time is adjusted through the first voltage dividing resistor R2, the second voltage dividing resistor R3 and the capacitor C1, and the capacitor C1 is turned on after the voltage across the capacitor C1 is greater than the base-emitter voltage of the transistor Q1; wherein the voltage across the capacitor C1 is:

[0028] ;

[0029] The current flowing through the second voltage dividing resistor R3 is:

[0030] ;

[0031] The current flowing through the first voltage dividing resistor R2 is:

[0032] ;

[0033] Therefore, the voltage across the capacitor C1 is:

[0034]

[0035] After rearrangement, it becomes the standard first-order linear differential equation, and the standard differential equation is:

[0036] ;

[0037] Wherein: .

[0038] By comparing the standard first-order system differential equation, it can be seen that the time constant is the inverse of K, that is, in actual engineering application, the related parameters can be adjusted to realize the fine-tuning effect of the blanking time, that is, to control the noise immunity delay thereof.

[0039] It should be particularly pointed out that the various resistors and capacitors involved in the embodiment can be selected according to actual needs, and the embodiment does not make a unique limitation thereto.

[0040] It is apparent for a person skilled in the art that the present application is not limited to the details of the above-described exemplary embodiments, but that it can be implemented in other concrete forms without departing from the spirit or the essential characteristics of the present application. Therefore, the embodiments should be considered as exemplary and non-limiting, the scope of the present application being defined by the claims appended hereto rather than by the above description, and all the changes which fall within the meaning and the scope of the equivalent elements of the claims are intended to be embraced therein. Any reference signs in the claims should not be construed as limiting the claims to the figures in which the reference signs are used.

[0041] Furthermore, it should be understood that although the present specification describes exemplary embodiments, not every embodiment contains only one independent technical solution, and the present specification is described in this way only for the sake of clarity, and a person skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that a person skilled in the art can understand.

Claims

1. A power device overcurrent short circuit protection circuit, characterized by, A first voltage dividing resistor (R2), a second voltage dividing resistor (R3), a first amplitude control resistor (Rs1) and a second amplitude control resistor (Rs2) are connected in sequence between a power device driving signal circuit and a desaturation detection circuit; the first voltage dividing resistor (R2) is connected with a power device driving signal output terminal of a chip; a connection point between the first amplitude control resistor (Rs1) and the second voltage dividing resistor (R3) is connected with a collector (IGBT-C) of a power device through one branch, and a triode (Q1) is arranged between the other branch and the power device driving signal output terminal of the chip; the second amplitude control resistor (Rs2) is connected with an emitter (IGBT-E) of the power device; a connection point between the first amplitude control resistor (Rs1) and the second amplitude control resistor (Rs2) is used as an input terminal of the desaturation detection circuit; and the second voltage dividing resistor (R3) is connected in parallel with a capacitor (C1).

2. The power device overcurrent short circuit protection circuit of claim 1, wherein, The power device driving signal output terminal of the chip sends a power device driving signal to a gate (IGBT-G) of the power device.

3. The power device overcurrent short circuit protection circuit of claim 1, wherein, A third voltage dividing resistor (R1) is arranged between the power device driving signal output terminal of the chip and a collector of the triode (Q1).

4. The power device overcurrent short circuit protection circuit of claim 1, wherein, A connection point between the first voltage dividing resistor (R2) and the second voltage dividing resistor (R3) is used as a base input terminal of the triode (Q1).

5. The power device overcurrent short circuit protection circuit of claim 1, wherein, An emitter of the triode (Q1) is connected with a connection point between the first amplitude control resistor (Rs1) and the second voltage dividing resistor (R3).

6. The power device overcurrent short circuit protection circuit of claim 1, wherein, The power device driving signal circuit comprises a shunt resistor (Rlim) and a reverse diode (D-HV); the shunt resistor (Rlim) is connected with a connection point between the first amplitude control resistor (Rs1) and the second voltage dividing resistor (R3), and the reverse diode (D-HV) is connected with the collector (IGBT-C) of the power device.

7. The power device overcurrent short circuit protection circuit of claim 6, wherein, The power device driving signal circuit further comprises a charging capacitor (Cblk), which is connected between the shunt resistor (Rlim) and the emitter (IGBT-E) of the power device.

8. The power device overcurrent short circuit protection circuit of claim 1, wherein, The desaturation detection circuit comprises a comparator (COMP); a connection point between the first amplitude control resistor (Rs1) and the second amplitude control resistor (Rs2) is used as an input terminal of the comparator (COMP).

9. The power device overcurrent short circuit protection circuit of claim 8, wherein, The connection point between the first amplitude control resistor (Rs1) and the second amplitude control resistor (Rs2) is used as a positive input terminal of the comparator (COMP), a negative input terminal of the comparator (COMP) inputs a preset reference voltage (REF), and an output terminal of the comparator (COMP) sends a desaturation detection signal to the chip.

10. The power device overcurrent short circuit protection circuit of claim 9, wherein, The chip determines the signal level of the power device driving signal output terminal based on the desaturation detection signal.

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