1. The utility model provides a static output characteristic detecting system of IGBT which characterized in that: the IGBT power supply comprises an inductor L1, an inductor L2, a current sampling sensor CT, a freewheeling diode D, a capacitor C and a direct-current power supply U, wherein the positive electrode of the direct-current power supply is connected with the collector electrode of the IGBT to be tested after sequentially passing through the inductors L2 and L1; the emitting electrode of the IGBT to be tested is connected to the negative electrode of the direct-current power supply U through the current sampling sensor; the collector of the IGBT to be tested is connected with the anode of a freewheeling diode D, and the cathode of the freewheeling diode D is connected with the anode of a direct-current power supply U; the capacitor C is connected in parallel at two ends of the direct current power supply U; and the grid electrode of the IGBT to be tested is connected with a driving signal through a resistor R.

2. The IGBT static output characteristic detection system according to claim 1, characterized in that: and a single-pulse test voltage is input to the grid of the IGBT to be tested.

3. The IGBT static output characteristic detection system according to claim 2, wherein: the single-pulse test voltage is generated by a signal generator, the pulse waveform is square wave, the pulse amplitude is the voltage value of the tested grid electrode, and the pulse width is adjustable according to the experiment requirement.

4. The IGBT static output characteristic detection system according to claim 1 or 2, characterized in that: the current sampling sensor CT outputs the acquired current signal to the oscilloscope, the output end of the oscilloscope is connected to the computer, and the computer is used for calculating and outputting the static output characteristic curve of the IGBT to be tested.

5. The IGBT static output characteristic detection system according to claim 1, characterized in that: the inductor L1 is a magnetic core inductor, and the inductor L2 is an air core inductor.

6. A detection method based on the IGBT static output characteristic detection system as claimed in any one of claims 1-4, characterized in that: the detection of the static output characteristic of the IGBT is realized according to the following control method and steps:

a. building a test system circuit in claim 1, and connecting elements in the system together;

b. starting a detection system, outputting power by a direct current power supply, generating a single pulse test voltage to a grid electrode of the IGBT by a signal generator, and outputting current to an oscilloscope by a current sensor;

c. the oscilloscope stores the acquired current waveform into a computer, and the computer calculates the IGBT conduction voltage value;

d. and drawing an IGBT static output characteristic curve according to the current value of the current waveform and the calculated IGBT conducting voltage value.

Background

With the rapid development of power semiconductor devices, the development of high-voltage and high-power solid-state switches by connecting power semiconductor devices in series and in parallel has become one of the development directions of pulse power at present. The high-voltage and high-current switch developed by adopting the power semiconductor IGBT basically has ideal switching performance and is widely applied to the fields of radar transmitters, radio frequency accelerators, cancer treatment, material surface treatment and the like.

The static output characteristic of the IGBT intuitively reflects the corresponding relation between the on-state voltage drop and the on-state current of the IGBT under different gate voltages, and the method has guiding significance for determining the on-state loss of the IGBT. The IGBT static output characteristic is also called a volt-ampere characteristic, and describes a relationship between a collector current Ic and a collector-emitter voltage Uce when a gate voltage is used as a parameter. It is similar to the output characteristics of GTR, except that the control variable, IGBT is the gate-emitter voltage Uge, and GTR is the base current I_b. The output characteristics of the IGBT are divided into 3 regions: the forward blocking region, the active region, and the saturation region correspond to the cutoff region, the amplification region, and the saturation region of the GTR. When UceE<At 0, the IGBT is in a reverse blocking state. In a power electronic circuit, an IGBT operates in a switching state, switching between a forward blocking region and a saturation region. The static output characteristic tester of IGBT that can adopt among the prior art gathers, but the test of instrument is complicated, and the instrument cost is than higher simultaneously, and based on this, this application provides a new simple circuit and realizes that the static output characteristic of IGBT detects.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a system and a method for detecting the static output characteristic of an IGBT (insulated gate bipolar transistor), which are used for quickly and simply realizing the detection of the output characteristic through a circuit.

In order to achieve the purpose, the invention adopts the technical scheme that: the IGBT static output characteristic detection system comprises an inductor L1, an inductor L2, a current sampling sensor CT, a freewheeling diode D, a capacitor C and a direct-current power supply U, wherein the anode of the direct-current power supply is connected with the collector of the IGBT to be detected after sequentially passing through the inductor L2 and the inductor L1; the emitting electrode of the IGBT to be tested is connected to the negative electrode of the direct-current power supply U through the current sampling sensor; the collector of the IGBT to be tested is connected with the anode of a freewheeling diode D, and the cathode of the freewheeling diode D is connected with the anode of a direct-current power supply U; the capacitor C is connected in parallel at two ends of the direct current power supply U; and the grid electrode of the IGBT to be tested is connected with a driving signal through a resistor R.

And a single-pulse test voltage is input to the grid of the IGBT to be tested. The single pulse test voltage can be generated by a signal generator, the pulse waveform is square wave, the pulse amplitude is the tested grid voltage value, and the pulse width can be adjusted according to the experiment requirement.

The current sampling sensor CT outputs the collected current signal to the oscilloscope. The current sampling sensor CT may employ a rogowski coil.

The inductor L1 is a magnetic core inductor, and the inductor L2 is an air core inductor.

A detection method of an IGBT static output characteristic detection system is used for realizing the detection of the IGBT static output characteristic according to the following control method and steps.

a. A test circuit is built as claimed in claim 1.

b. Test equipment such as current collection sensors CT, oscilloscopes, signal generators are prepared according to claim 1.

c. The oscilloscope stores the acquired current waveform into a computer, the waveform is stored in an excel table form, A column is the value of the current, and B column is the time value. Column C is a differential value of the current with time obtained by calculation. And D column is the IGBT on voltage value. The value of column D is equal to the value of the power supply voltage minus the value of column A times the line resistance minus the value of the inductance times the value of column C

d. And drawing an IGBT static output characteristic curve according to the A column current value and the D column voltage value.

The invention has the advantages that: the IGBT static output characteristic curve detection device is simple in structure, convenient to achieve, capable of rapidly detecting the IGBT static output characteristic curve, reliable in detection result and low in implementation cost.

Drawings

The contents of the expressions in the various figures of the present specification and the labels in the figures are briefly described as follows:

FIG. 1 is a schematic circuit diagram of a detection system of the present invention;

fig. 2 is a schematic diagram of the circuit equivalent of the present invention.

FIG. 3 is a characteristic diagram of static output of IGBT

Detailed Description

The following description of preferred embodiments of the invention will be made in further detail with reference to the accompanying drawings.

The invention provides a brand-new IGBT static output characteristic test method. The inductive load is adopted to carry out single-pulse test, and the static output characteristic curve of the IGBT under a certain gate voltage can be obtained in a short time. The inductive load is composed of L₁And L₂Are connected in series to form₁Larger, but smaller saturation current; l is₂Small but the saturation current is large. By means of L₁The saturation principle of the circuit can realize automatic switching of the load of the test circuit, so that the low current section of the circuit works under a large inductive load and the high current section works under a small inductive load.

As shown in fig. 1 and 2, in fig. 1, U is a direct current power supply; c, a bus capacitor group (with large capacitance value); l is₁Magnetic core inductance (larger inductance value and smaller saturation current); l is₂Hollow inductor (smaller inductance value, larger saturation current); d, a freewheeling diode; v1, IGBT to be tested; and R is a grid driving resistor.

In fig. 2, Rs is the equivalent resistance of the line; l is₁、L₂C is as defined in fig. 1.

As shown in FIG. 1, the positive pole of the power source U is connected to the capacitor L₂One end of, L₂Another terminal of which is connected to the capacitor L₁One end of, L₁The other end of the current sampling probe is connected to the collector of the V1, and the emitter of the V1 is connected to the negative pole of the power supply U through the current sampling probe CT.

As shown in fig. 1, the collector of V1 is connected to the anode of D, and the cathode of D is connected to the anode of power supply U.

As shown in fig. 1, a capacitor C is incorporated across the power source U, and the driving signal is coupled to the gate of V1 through a resistor R.

The circuit detection adopts a single pulse test time sequence t₀At the moment V1, the grid voltage is raised, V1 is conducted, and the load L with large inductance is subjected to₁Down run, elapsed time t1_，L₁And (4) saturation. V1 at small inductive load L₂In the lower operation, after time t2, the gate voltage of V1 becomes low and V1 is turned off. And the diode D freewheels until the current drops to zero, and the test is finished.

When the driving signal comes, at L₁Before saturation, due to I₀The (saturation current) is very small, the bus voltage drop is very small in the whole test process, the bus voltage is considered to be constant voltage, and the relationship between the loop current and the bus voltage is the following formula (1).

When L is₁After saturation, the loop inductance is substantially L₂The loop current rapidly rises, and the relationship between the parameters is the following expression (2).

t₂＝(L₂/R_S)ln[(U-I₀R_S)/(U-IR_S)] (2)

The loop current rise rate is the following equation (3).

In the above formulas (1), (2) and (3)

L1: inductance value of large inductor

L2: inductance value of small inductor

U: voltage value of power supply

Rs: testing resistance of loop

I0: saturated current value of inductor L1

I measured current value

The detection of the static output characteristic of the IGBT is realized according to the following control method and steps.

a. A test circuit is built as claimed in claim 1.

b. Test equipment such as current collection sensors CT, oscilloscopes, signal generators are prepared according to claim 1.

c. The oscilloscope stores the acquired current waveform into a computer, the waveform is stored in an excel table form, A column is the value of the current, and B column is the time value. Column C is a differential value of the current with time obtained by calculation. And D column is the IGBT on voltage value. The value of column D is equal to the value of the power supply voltage minus the value of column A times the line resistance minus the value of the inductance times the value of column C

d. And drawing an IGBT static output characteristic curve according to the A column current value and the D column voltage value.

The IGBT static output characteristic measured by the method is basically consistent with the result measured by the IGBT static output characteristic tester.

It is clear that the specific implementation of the invention is not restricted to the above-described embodiments, but that various insubstantial modifications of the inventive process concept and technical solutions are within the scope of protection of the invention.