CN218331832U

CN218331832U - IGBT threshold voltage measuring circuit

Info

Publication number: CN218331832U
Application number: CN202222304487.5U
Authority: CN
Inventors: 赵玉斌; 刘青健
Original assignee: Qingdao Hisense Hitachi Air Conditioning System Co Ltd
Current assignee: Qingdao Hisense Hitachi Air Conditioning System Co Ltd
Priority date: 2022-08-30
Filing date: 2022-08-30
Publication date: 2023-01-17
Anticipated expiration: 2032-08-30

Abstract

The utility model discloses a IGBT threshold voltage measurement circuit, include: the power switch is provided with a power supply position and a power-off position, the power supply position is connected with a first power supply, the power-off position is connected with a power ground, and the power switch is connected with the base electrode of the IGBT to be tested through a current-limiting resistor; the collector electrode of the IGBT to be tested is connected with the second power supply; the current collecting unit is used for collecting the driving current flowing through the collector electrode of the IGBT to be tested; the voltage acquisition unit is used for acquiring the voltage between the base electrode and the emitting electrode of the IGBT to be tested; and the main control unit is respectively connected with the current acquisition unit and the voltage acquisition unit. The utility model is used for measure IGBT threshold voltage for the screening IGBT provides data support.

Description

IGBT threshold voltage measuring circuit

Technical Field

The utility model relates to a power electronic technology field especially relates to a IGBT threshold voltage measurement circuit.

Background

An IGBT (Insulated Gate Bipolar Transistor) is a composite fully-controlled voltage-driven power semiconductor device composed of a Bipolar Transistor and an Insulated Gate field effect Transistor, and has the advantages of both high input impedance of a mosfet and low on-state voltage drop of a power Transistor.

With the increasing market demand for megawatt high-power frequency converters, the IGBT parallel connection scheme has become a trend at present, which mainly comes from the advantages that the IGBT parallel connection can provide higher current density, uniform heat distribution, flexible layout, higher cost performance and the like.

When the IGBTs are used in parallel, the parameter influencing the dynamic current sharing of the IGBTs is the threshold voltage VGEth, the lower the threshold voltage is, the faster the opening speed of the MOS channel of the IGBT is, the faster the collector current rises, the more the current flowing through the IGBT is, the higher the temperature rise is, the shorter the service life is, and the higher the possibility of damaging the IGBT is.

At present, when the IGBT is used, the threshold voltage of the IGBT is generally not measured and is selected according to the range of the threshold voltage in the specification of the IGBT, and the threshold voltage range of the IGBT is large, so that dynamic current sharing cannot be ensured when the selected IGBT is connected in parallel, and the damage risk of the IGBT is large.

Disclosure of Invention

The utility model provides a IGBT threshold voltage measurement circuit for measure IGBT threshold voltage, be used for screening IGBT to provide data support.

The application provides an IGBT threshold voltage measurement circuit, includes:

the power switch is provided with a power supply position and a power off position, the power supply position is connected with a first power supply, the power off position is connected with a power ground, and the power switch is connected with the base electrode of the IGBT to be tested;

the collector electrode of the IGBT to be tested is connected with the second power supply;

the current collecting unit is used for collecting the driving current flowing through the collector electrode of the IGBT to be tested;

the voltage acquisition unit is used for acquiring the voltage between the base electrode and the emitting electrode of the IGBT to be tested;

and the main control unit is respectively connected with the current acquisition unit and the voltage acquisition unit.

Through the voltage acquisition unit and the current acquisition unit that provide, the main control unit can output IGBT's threshold voltage, provides data support for screening IGBT, is convenient for select the IGBT that threshold voltage is close when IGBT connects in parallel and uses, ensures that IGBT developments flow equalize, improves the device and uses the reliability.

In some embodiments of the present application, the power switch is a manual switch having an open position and a closed position;

the open position corresponds to the power position and the closed position corresponds to the power-off position.

The IGBT can be provided with driving voltage by manually controlling the power switch.

In some embodiments of the present application, the IGBT threshold voltage measurement circuit further comprises:

the switch control circuit comprises a power supply, a relay and a switch control element connected to a power supply loop of the power supply for supplying power to the relay;

the control end of the switch control element is connected with the main control unit; one end of the switch control element is connected with the power supply, and the other end of the switch control element is connected with the relay;

the power switch is a single-pole double-throw switch of the relay, a normally open contact in the single-pole double-throw switch is connected with the first power supply, a normally closed contact is connected with the ground, and a common contact is connected with one end of the current-limiting resistor;

the normally open contact and the public contact form the power supply position when connected, and the normally closed contact and the public contact form the power failure position when connected.

And the main control unit sends a control signal to realize the automatic electrification of the coil of the relay.

In some embodiments of the present application, when the switch control element is a high-level conducting switch element, the switch control element is an NPN transistor, and a base of the NPN transistor is connected to the main control unit;

when the switch control element is a switch element conducted at a low level, the switch control element is a PNP triode, and the base electrode of the PNP triode is connected with the main control unit.

In some embodiments of the present application, to ensure stability to the IGBT base voltage, the IGBT threshold voltage measurement circuit further includes:

and the filtering unit is connected to the front end of the base electrode of the IGBT to be tested.

In some embodiments of the present application, the current collection unit includes:

the current sensor is connected between the positive terminal of the second power supply and the collector electrode of the IGBT to be tested in series;

and the ammeter is connected in the current loop of the current sensor in series and is connected with the main control unit.

In some embodiments of the present application, the current collecting unit is a sampling resistor connected in series between the positive terminal of the second power supply and the collector of the IGBT to be tested.

In some embodiments of the present application, the voltage acquisition unit is:

and the voltmeter is connected in parallel between the base electrode and the emitting electrode of the IGBT to be tested.

In some embodiments of the present application, the master control unit is integrated with a first analog-to-digital converter, a second analog-to-digital converter and a digital-to-analog converter;

the output end of the current acquisition unit is connected with the first analog input port of the first analog-to-digital converter;

a first digital output port of the first analog-to-digital converter is connected with the main control unit;

the output end of the voltage acquisition unit is connected with a second analog input port of the second analog-to-digital converter;

a second digital output port of the second analog-to-digital converter is connected with the main control unit;

the control unit is connected with the digital-to-analog converter.

The output of the lower threshold voltage of the output driving current is realized through the analog-to-digital conversion and the digital-to-analog conversion.

a first input end of the first comparison unit is connected with an analog output end of the digital-to-analog converter, and a second input end of the first comparison unit is connected with an upper limit value of a threshold voltage screening range;

a first input end of the second comparison unit is connected with an analog output end of the digital-to-analog converter, and a second input end of the second comparison unit is connected with a lower limit value of the threshold voltage screening range;

and the first input end of the AND gate unit is connected with the output end of the first comparison unit, the second input end of the AND gate unit is connected with the output end of the second comparator, and the output end of the AND gate unit is connected with the main control unit.

By setting the threshold voltage screening range, the IGBT having the threshold voltage within the screening range can be screened.

Drawings

FIG. 1 shows a block diagram of an IGBT threshold voltage measurement circuit according to some embodiments;

FIG. 2 illustrates yet another block diagram of an IGBT threshold voltage measurement circuit in accordance with some embodiments;

FIG. 3 illustrates a circuit diagram of a power switch in an IGBT threshold voltage measurement circuit, in accordance with some embodiments;

FIG. 4 illustrates another circuit diagram of a power switch in an IGBT threshold voltage measurement circuit according to some embodiments;

FIG. 5 illustrates another block diagram of an IGBT threshold voltage measurement circuit according to some embodiments;

FIG. 6 illustrates a schematic diagram of an IGBT threshold voltage measurement circuit, in accordance with some embodiments;

FIG. 7 illustrates yet another schematic diagram of an IGBT threshold voltage measurement circuit, in accordance with some embodiments;

fig. 8 shows a schematic diagram of the connection of a main control unit, a current collection unit and a voltage collection unit in an IGBT threshold voltage measurement circuit according to some embodiments;

fig. 9 shows a schematic diagram of the connection of a first comparison unit, a second comparison unit and an and gate unit in an IGBT threshold voltage measurement circuit according to some embodiments;

fig. 10 shows a circuit diagram of an indication unit in an IGBT threshold voltage measurement circuit according to some embodiments.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts all belong to the protection scope of the present invention.

In the description of the present invention, it is to be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are merely for convenience of description and simplicity of description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore, are not to be construed as limiting the present invention.

The terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless otherwise specified.

In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood in specific cases to those skilled in the art.

In the present disclosure, unless expressly stated or limited otherwise, the first feature "on" or "under" the second feature may comprise direct contact between the first and second features, or may comprise contact between the first and second features not directly. Also, the first feature "on," "above" and "over" the second feature may include the first feature being directly above and obliquely above the second feature, or simply indicating that the first feature is at a higher level than the second feature. "beneath," "under" and "beneath" a first feature includes the first feature being directly beneath and obliquely beneath the second feature, or simply indicating that the first feature is at a lesser elevation than the second feature.

The following disclosure provides many different embodiments or examples for implementing different features of the invention. In order to simplify the disclosure of the present invention, the components and arrangements of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. Furthermore, the present invention may repeat reference numerals and/or reference letters in the various examples, which have been repeated for purposes of simplicity and clarity and do not in themselves dictate a relationship between the various embodiments and/or arrangements discussed. In addition, the present disclosure provides examples of various specific processes and materials, but one of ordinary skill in the art may recognize applications of other processes and/or use of other materials.

Referring to fig. 1 to 10, the present application relates to measurement of the threshold voltage of an IGBT to be tested as a data basis for screening IGBTs for parallel use.

Referring to fig. 1 to 4, the IGBT threshold voltage measurement circuit provided by the present application includes a power switch 10, a first power DC1+, a second power DC2+, a current collection unit 30, a voltage collection unit 40, and a main control unit 20.

And power is supplied or not supplied to the base electrode of the IGBT Q1 to be tested through the power switch 10.

[ Power supply switch ]

The power switch 10 has three terminals: a supply terminal a, a ground terminal B and a common terminal CO, the three terminals forming the supply position and the off position of the power switch 10.

The power supply end A is connected with a first power supply DC1+, the grounding end B is connected with a power supply ground, and the common end CO is connected with the base of the IGBT Q1 through a current-limiting resistor.

When the power supply terminal A is connected with the public terminal CO, a power supply position is formed; when the ground terminal B and the common terminal CO are connected, a power-off position is formed.

When the power switch 10 is located at a power supply position, the first power supply DC1+ can provide electric energy for the base electrode of the IGBT Q1 to be tested; when the power switch 10 is located at the power-off position, no electric energy is provided for the base of the IGBT Q1 to be tested.

And an emitter of the IGBT Q1 to be tested is connected with a second power supply DC2+, and a collector is grounded.

In this way, when the power switch 10 is located at the power supply position, the IGBT Q1 is turned on, and the second power supply DC2+ generates the driving current Ic, which can be collected by the current collecting unit 30, through the emitter of the IGBT Q1.

The voltage collecting unit 40 is used to collect a voltage between the base and emitter of the IGBT Q1 when it is turned on, i.e., a threshold voltage VGE.

It should be noted that the IGBT Q1 to be tested according to the present application is a P-channel IGBT turned on at a high level.

In some embodiments of the present application, the power switch 10 may be a manual control button.

When the manual key is pressed, the power switch 10 is in the power supply position, and the first power supply DC1+ can supply power to the base of the IGBT Q1.

When the manual button is pressed again and bounced, the power switch 10 is in the power-off position, and at the moment, the first power supply 10 is disconnected to supply power to the base of the IGBT Q1.

In some embodiments of the present application, the power switch 10 may be a manually controlled single pole double throw switch.

The first movable end of the single-pole double-throw switch is a power supply end A, the second movable end of the single-pole double-throw switch is a grounding end B, and the static end of the single-pole double-throw switch is a common end CO.

When the power switch 10 is manually opened to communicate the first moving end with the static end, the first power supply DC1+ supplies power to the base of the IGBT Q1, and when the power switch 10 is manually opened to communicate the second moving end with the static end, the first power supply DC1+ does not supply power to the base of the IGBT Q1.

In some embodiments of the present application, it may also be a switch that is automatically controlled by an electrical signal.

Referring to fig. 3 and 4, the power switch 10 is selected as a single pole double throw switch of the relay KM.

A normally open contact in the single-pole double-throw switch is a power supply end A, a normally closed contact is a power-off end B, and a common contact is a common end CO.

The normally open contact and the common contact form a power supply position when connected, and the normally closed contact and the common contact form a power off position when connected.

When the coil of the relay KM is electrified, the normally open contact is communicated with the common contact, the first power supply DC1+ supplies power to the base of the IGBT Q1, and when the coil of the relay KM is not electrified, the normally closed contact is communicated with the common contact, and the first power supply DC1+ does not supply power to the base of the IGBT Q1.

The coil of the relay KM is powered on or powered off under the control of a control signal OUT sent by the main control unit 10.

Referring to fig. 3 and 4, the IGBT threshold voltage measurement circuit further includes a switch control circuit 50 for receiving a control signal OUT and supplying power to the coil of the relay KM.

The switch control circuit 50 includes a power supply VCC (e.g., +12V DC), a relay KM, and a switch control element connected to a power supply loop where the power supply VCC supplies power to the coil of the relay KM.

The control end of the switch control element receives a control signal OUT sent by the main control unit 10, one end of the switch control element is connected with a power supply VCC, and the other end of the switch control element is connected with a relay KM coil.

When the switch control element receives the control signal OUT, the switch control element is turned on, so that the power supply VCC supplies power to the coil of the relay KM.

The switch control element may be a high-level on switch element or a low-level on switch element.

The control signal OUT needs to be at a high level when the switching control element is a switching element that is turned on at a high level, and needs to be at a low level when the switching control element is a switching element that is turned on at a low level.

When the switch control element is a high-level conducting switch element, the control end of the high-level conducting switch element receives a control signal OUT, a reverse diode D1 and a relay KM coil which are arranged in parallel are connected between the first end of the high-level conducting switch element and the ground, and the second end of the high-level conducting switch element is connected with a power supply VCC through a pull-up resistor R4'.

Referring to fig. 3, the high-level conducting switching element is an NPN transistor Q21.

A base electrode of the NPN triode Q21 may receive a control signal OUT output by the main control unit 20 through a base current limiting resistor R2', a reverse diode D1 and a relay KM coil, which are connected in parallel, are connected between an emitter electrode and the ground, and a collector electrode is connected to a power supply VCC through a pull-up resistor R4'.

The base current limiting resistor R2' is used for limiting the current flowing into the base of the NPN triode Q21, so that the NPN triode Q21 is prevented from being burnt when the level of the output control signal OUT is unstable or high, and the NPN triode Q21 is protected.

A base pull-down resistor R3' may also be added at the base of the NPN transistor Q21.

The base pull-down resistor R3 'is used for ensuring the normal work of the NPN triode Q21 and preventing the NPN triode Q21 from generating false operation under the influence of noise signals, so that the NPN triode Q21 is more reliably cut off, the base of the NPN triode Q21 cannot be suspended, when input signals are uncertain (such as when the input signals are in a high-resistance state), the base pull-down resistor R21 is added, effective grounding can be achieved, and discharging can be achieved through the base pull-down resistor R3' when the NPN triode Q21 is cut off.

The reverse diode D1 prevents the relay KM from being short-circuited when the NPN transistor Q21 is turned on.

When the control signal OUT is at a low level, the NPN triode Q21 is cut off, and VCC does not supply power to the relay KM, so that the normally open contact of the relay KM is kept open.

When the control signal OUT is at a high level, the NPN triode Q21 is conducted, the VCC supplies power to the relay KM, and therefore the normally open contact of the relay KM is closed.

When the switch control element is a low-level conducting switch element, the control end of the low-level conducting switch element receives a control signal OUT, a reverse diode D1 and a relay KM coil which are arranged in parallel are connected between the first end of the low-level conducting switch element and the ground, and the second end of the low-level conducting switch element is connected with a power supply VCC.

Referring to fig. 4, the low-level conducting switch element is a PNP transistor Q22, a base of the transistor Q22 receives a control signal OUT output by the main control unit 20 through a base current limiting resistor R5', a reverse diode D1 and a relay KM coil are connected in parallel between a collector and ground, and an emitter is connected to a power supply VCC.

The base current limiting resistor R5' is used for limiting the current flowing into the base of the PNP triode Q22, so that the PNP triode Q22 is prevented from being burnt when the level of the control signal OUT is unstable or high, and the PNP triode Q22 is protected.

A base pull-up resistor R6' may also be added at the base of the PNP transistor Q22.

When the output level of the control signal OUT is unstable, the base pull-up resistor R6' pulls the base to a determined high level, so that misoperation is prevented.

The reverse diode D1 prevents the PNP transistor Q22 from shorting the relay KM when it is turned on.

When control signal OUT is the low level, PNP triode Q22 switches on, and VCC supplies power to relay KM normally open contact is closed.

When the control signal OUT is at a high level, the PNP triode Q22 is cut off, and VCC does not supply power to the relay KM, so that the normally open contact of the relay KM is kept open.

Referring to fig. 5 and 6, in order to ensure stability of power of the first power source DC1+ to the base of the IGBT Q1, a filter unit 60 is provided at a front end of the base of the IGBT Q1.

The filtering unit 60 may include a capacitor C1 and a resistor R2 connected in parallel to filter noise of the first power DC1 +.

The IGBT threshold voltage measuring circuit can be designed in a box body to form a measuring instrument, and the power switch 10 is arranged on the front side panel of the box body, so that the operation is convenient.

[ Current collecting Unit/Voltage collecting Unit ]

Referring to fig. 6 and 7, the current collection unit 30 is used for collecting the driving current Ic and is connected to the main control unit 20.

The current collecting unit 30 collects current by using a sampling resistor Rs and a peripheral circuit, and may also collect current by using an ammeter.

The voltage collecting unit 40 is used for collecting the voltage between the base and the emitter of the IGBT Q1, and is connected to the main control unit 20.

Similarly, the voltage acquisition unit 40 performs voltage acquisition by using a voltmeter, and may also perform acquisition by using a sampling resistor.

In some embodiments of the present application, the current collecting unit 30 is taken as an ammeter, and the voltage collecting unit 40 is taken as a voltmeter.

Since the ammeter needs to be connected in series in the loop, in the present application, the current sensor C1 is connected in series in the power supply loop from the second power supply DC2+ to the collector of the IGBT Q1, and the ammeter is connected in series with the current sensor CT 1.

Namely, the primary side of the current sensor CT1 is connected in series in the power supply loop, and the secondary side is connected in series with the ammeter.

In some embodiments of the present application, after the current collecting unit 30 collects the driving current Ic and the voltage collecting unit 40 collects the threshold voltage VGE, the main control unit 20 may output the driving current Ic and the threshold voltage VGE in the form of text or graph.

The measuring person can obtain the value of the selected driving current Ic (note: the preset driving current (e.g., IA)) and output the corresponding value of the threshold voltage VGE (note: the threshold voltage VGE (th)) according to the output driving current Ic and the threshold voltage VGE.

In some embodiments of the present application, the corresponding threshold voltage VGE may be output according to the value of the selected drive current Ic (i.e., the preset drive current).

Referring to fig. 8, the main control unit 20 is integrated with a first analog-to-digital converter 60, a second analog-to-digital converter 60', and a digital-to-analog converter 60 ″; of course, the analog-to-digital converter and the digital-to-analog converter may be provided independently of the main control unit 20.

Referring to fig. 8, the following description is made.

In order to output the threshold voltage under the preset driving current, the ammeter obtains the driving current Ic to the analog input terminal of the first analog-to-digital converter 60, and outputs a first digital signal at the digital output terminal of the first analog-to-digital converter 60 after analog-to-digital conversion, and outputs the first digital signal to the main control unit 20.

The voltmeter obtains a threshold voltage to an analog input end of the second analog-to-digital converter 60', and outputs a second digital signal at a digital output end of the second analog-to-digital converter 60' after analog-to-digital conversion, and outputs the second digital signal to the main control unit 20.

The main control unit 20 receives the first digital signal, and if the current corresponding to the first digital signal is a predetermined driving current (e.g., 1A), the main control unit 20 stores the second digital signal at this time.

The analog output port of the digital-to-analog converter 60 ″ outputs the analog quantity Vout corresponding to the second digital signal.

At this time, vout is the threshold voltage under the preset driving current, and is denoted as Vge (th).

If the screening range of the threshold voltage is specified to be +/-90 mV by a measurer, whether the threshold voltage of the IGBT to be tested meets the screening range can be judged manually according to the obtained Vge (th).

That is, if the threshold voltage VGE of the IGBT acquired at the preset drive current is within the range between VGE (th) -90mV and VGE (th) +90mV, it indicates that the IGBT screening is acceptable.

The IGBT which is qualified in screening can adopt a parallel design, thereby ensuring dynamic flow equalization and reducing the possibility of IGBT damage.

In some embodiments of the present application, in order to achieve automatic determination of whether the threshold voltage of the IGBT to be tested satisfies the screening range, referring to fig. 9, the IGBT threshold voltage measurement circuit further includes a first comparison unit 70, a second comparison unit 70', and an and gate unit 80.

First, according to the screening range, for example, ± 90mV, the upper limit value V1= Vge (th) +90mV of the threshold voltage screening range is obtained by the first voltage summing circuit, and the lower limit value V2= Vge (th) -90mV of the threshold voltage screening range is obtained by the second voltage summing circuit.

The first voltage summing circuit and the second voltage summing circuit are both existing circuits and can be built by adopting an integrated amplifier and a plurality of resistors.

The first comparing unit 70 has a first input terminal (e.g., a positive terminal) receiving Vout and a second input terminal (e.g., a negative terminal) receiving V1 output from the first voltage summing circuit.

When Vout is less than V1, the first comparing unit 70 should output a low level.

The second comparing unit 70' has a first input terminal (e.g., a positive terminal) receiving Vout and a second input terminal (e.g., a negative terminal) receiving V2 output from the second voltage summing circuit.

When Vout is greater than V2, the second comparing unit 70' should output a high level.

The output terminal of the first comparing unit 70 and the output terminal of the second comparing unit 70' are respectively input to the and gate unit 80.

The output of the and gate unit 80 is connected to the main control unit 20.

When the current IGBT meets the screening requirement, i.e., vout is smaller than V1 and Vout is larger than V2, the and gate unit 80 outputs a low level.

That is, when the current IGBT meets the screening requirement, a low level is received at the receiving port of the main control unit 20.

In order to visually show whether the current IGBT to be tested meets the screening requirement or not to the measuring personnel, an indicating unit 90 is further arranged.

The indicating unit 90 is connected to the main control unit 20, and is configured to output another control signal to the indicating unit 90 when the main control unit 20 receives the low level output by the and gate unit 80, so that the indicating unit 90 outputs an indication to visually feed back to a measurer that the current IGBT to be measured meets the screening requirement, and otherwise, the IGBT to be measured does not meet the screening requirement.

The indication unit 90 may be an audio indication circuit, an optical indication circuit or an acousto-optic indication circuit.

In some embodiments of the present application, referring to fig. 10, the indicating unit 90 is an optical indicating circuit.

The light indicating circuit comprises a resistor R51/R61/R71, a PNP triode Q23, an indicator light LED and a power supply VCC.

One end of the resistor R51 is connected to the output end of the main control unit 20 for receiving the other output control signal, the other end is connected to the base of the PNP triode Q23, the emitter is connected to the power supply VCC, and the indicator LED and the resistor R71 are connected in series between the collector and the ground.

A base pull-up resistor R61 may also be added at the base of PNP transistor Q23.

When the output level of another control signal is unstable, the base pull-up resistor R61 pulls the base to a determined high level, so that the malfunction is prevented.

When the main control unit 20 receives another control signal of low level, the PNP triode Q23 is turned on, and the indicator light LED emits a light indication to indicate that the current IGBT is qualified in screening, otherwise, the current IGBT is unqualified in screening.

It should be noted that Vout may also be input to the negative terminal of the first comparing unit 70 and the negative terminal of the second comparing unit 70', as long as Vout is input to the same input terminal of the first comparing unit 70 and the second comparing unit 70'.

The first comparing unit 70 and the second comparing unit 70' are implemented by using comparators, and the and gate unit 80 is implemented by using an and gate chip.

The IGBT threshold voltage measuring circuit can measure the threshold voltage of the IGBT and is beneficial to screening the IGBT within the threshold voltage screening range; the circuit is simple, convenient, easy to realize and low in cost.

In the foregoing description of embodiments, the particular features, structures, materials, or characteristics may be combined in any suitable manner in any one or more embodiments or examples.

The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. An IGBT threshold voltage measurement circuit, characterized by comprising:

2. The IGBT threshold voltage measurement circuit of claim 1, wherein the power switch is a manual switch having an open position and a closed position;

3. The IGBT threshold voltage measurement circuit according to claim 1, further comprising:

4. The IGBT threshold voltage measurement circuit of claim 3,

when the switch control element is a high-level conducted switch element, the switch control element is an NPN triode, and a base electrode of the NPN triode is connected with the main control unit;

5. The IGBT threshold voltage measurement circuit according to claim 1, further comprising:

6. The IGBT threshold voltage measurement circuit according to claim 1, wherein the current collection unit comprises:

7. The IGBT threshold voltage measurement circuit of claim 1, wherein the current collection unit is a sampling resistor connected in series between the positive terminal of the second power supply and the collector of the IGBT to be tested.

8. The IGBT threshold voltage measurement circuit of claim 1, wherein the voltage acquisition unit is:

9. The IGBT threshold voltage measurement circuit of claim 1,

the main control unit is integrated with a first analog-to-digital converter, a second analog-to-digital converter and a digital-to-analog converter;

the main control unit is connected with the digital-to-analog converter.

10. The IGBT threshold voltage measurement circuit of claim 9, further comprising: