CN109633405B - A device for junction temperature calibration and heat dissipation component performance evaluation based on bias current pre-compensation - Google Patents

Abstract

The invention provides a junction temperature calibration and heat dissipation component performance evaluation device based on bias current pre-compensation. The device includes two working modes: calibration and measurement. The calibration mode is composed of the device under test under constant current source excitation and the accompanying load in parallel. The saturation conduction voltage drop of the device under test at different junction temperatures can be obtained, and the relationship between the junction temperature and the saturation conduction voltage drop can be obtained; , control the saturation conduction voltage drop to make the device under test work under different heating power, measure the saturation conduction voltage drop of the device under test, and inversely infer the junction temperature of the device under test according to the relationship between the junction temperature and the saturation conduction voltage drop, The junction temperature characteristics of the device under different heating power are obtained to evaluate the heat dissipation performance of the heat dissipation component.

Description

A device for junction temperature calibration and heat dissipation component performance evaluation based on bias current pre-compensation

technical field

The invention relates to a junction temperature calibration and heat dissipation component performance evaluation device based on bias current pre-compensation, belonging to the technical field of reliability testing of power switching devices.

Background technique

When the power switch device converts and controls the electrical energy, it also produces a certain power loss on the chip, which leads to a sharp rise in the temperature of the chip. Therefore, the problem of avoiding device damage caused by overheating is a problem that must be considered in the working process of the power switching device. In order to facilitate heat dissipation, power switching devices need to be equipped with heat dissipation components. Therefore, the installation quality of power devices and heat dissipation components in actual engineering plays a crucial role in the overall heat dissipation performance of the device.

In order to evaluate the overall heat dissipation performance of the device, it is necessary to set the heating power of the device to obtain the junction temperature and detect whether it exceeds its maximum allowable junction temperature.

At present, there are mainly four kinds of mature junction temperature measurement methods for power switching devices, namely physical contact method, optical method, electrothermal coupling model method, and temperature-sensitive parameter method. The physical contact method mainly uses platinum resistance or thermocouple temperature sensor for contact measurement. During measurement, in order to make the thermal element fully contact with the chip surface of the device under test, the device package must be opened, and the measurement accuracy is easily affected by the installation quality of the temperature measuring element, so its operability is not strong; the optical method is generally used The infrared thermal imager measures the component under test non-contact, and can obtain the temperature distribution of the entire chip surface, which can meet the real-time junction temperature measurement requirements of the device under test. However, this measurement method also needs to open the device package, and the equipment is expensive, the measurement cost is high, and it also has high requirements for the measurement personnel; the electrothermal coupling model method is a commonly used junction temperature simulation method, which is established by the thermoelectric comparison theory. The thermal network model can be used to obtain the junction temperature and its variation trend in real time, which can realize online measurement. However, the thermal resistance is difficult to obtain in actual working conditions, so it cannot be applied; the temperature-sensitive parameter method indirectly measures the correlation between some state parameters of the device under test and the temperature in a specific temperature range. get the junction temperature. These state parameters are called temperature-sensitive parameters, and the temperature-sensitive parameters usually measured mainly include the saturation turn-on voltage drop V _ce-sat , the gate turn-on delay time t _d(on) , and the threshold voltage V _ge(th) .

At present, the junction temperature detection technology related to power switching devices has made great progress. Among them, the temperature-sensitive parameter method has become the main measurement method for junction temperature detection of power switching devices due to its advantages of low measurement cost, high accuracy and fast response. "An IGBT transient thermal characteristic testing device and its operation method" (patent application number: CN106353665A), by using an optical fiber temperature sensor to perform contact measurement on the tested IGBT, it is necessary to destroy the IGBT package structure, so the actual operability is not strong; "An IGBT junction temperature measurement device" (patent application number: CN201610525421) mainly measures the IGBT turn-off delay time t _d(off) and the IGBT collector current in real time, according to the IGBT junction temperature, IGBT collector current and IGBT turn-off The three-dimensional relationship of the delay time t _d(off) obtains the corresponding junction temperature of the IGBT. This method uses the turn-off delay time as a temperature-sensitive parameter, which has high measurement cost and high requirements for the experimental environment. It is difficult to realize the on-line measurement of the turn-off delay time of the IGBT under actual working conditions. The temperature calibration platform for junction temperature and the method for realizing IGBT junction temperature measurement" (patent application number: CN201510245724) is mainly to calibrate the three-dimensional relationship of IGBT saturated on-voltage drop, junction temperature and collector current in the environment of incubator. Then, the corresponding junction temperature is obtained by measuring the saturated on-state voltage drop and collector current. This method is difficult to ensure the consistency of the measurement and the bias conditions in the calibration mode, which affects the accuracy of the junction temperature measurement.

In the traditional junction temperature measurement method based on the temperature-sensitive parameter of the saturated on-state voltage drop, under the working condition of high current, in order to prevent the device from self-heating, the gate signal of the device under test is usually given a narrow pulse. At the same time, it is necessary to collect the saturated conduction voltage drop in a very short time, otherwise the measurement will be inaccurate due to the rapid rise of the junction temperature. Since the constant current source used in the measurement is not an ideal constant current source, its output current will be affected by the change of the voltage drop across the load, which will affect the accuracy of the junction temperature measurement result.

SUMMARY OF THE INVENTION

The present invention is mainly aimed at the problem that when the traditional temperature-sensitive parameter method based on the saturation conduction voltage drop measures the junction temperature, it ignores the problem that the working conditions of the device in the calibration mode and the measurement mode are different, resulting in the change of the bias conditions at the measurement moment and bring about errors. , a junction temperature calibration and heat dissipation component performance evaluation device based on bias current pre-compensation is proposed.

Without solving the above technical purpose, the present invention provides a junction temperature calibration and heat dissipation component performance evaluation device based on bias current pre-compensation. The components in the calibration mode include: an adjustable voltage source, an adjustable constant current source and a device under test Q1 A loop is formed in series; the negative electrode of the adjustable voltage source is the common ground; the device under test, the temperature sensor and the heat storage block are placed in a heat preservation container; the accompanying load Q2 is connected in parallel with the device under test Q1; the analog input end of A/D1 is connected to the test device Q1 The collector and emitter of the device Q1 are connected; A/D1 receives the conversion start signal of the controller and transmits the data result of the analog-to-digital conversion to the controller; the gate of the device under test Q1 is connected to the output terminal O of the gate driver 1 ; The power supply terminal V of gate driver 1 is connected to D/A1; D/A1 receives the data transmitted by the controller; the gate control signal output by the controller is connected to the control terminal C of gate driver 2, and the gate control signal passes through The NOT gate is connected to the control terminal C of the gate driver 1; the ground terminal G of the gate driver 1 is connected to the common ground; the gate of the accompanying load Q2 is connected to the output terminal O of the gate driver 2; the power terminal of the gate driver 2 V is connected to the output terminal of the operational amplifier D1; the non-inverting input terminal of the operational amplifier D1 is connected to the drain of the accompanying load Q2; the inverting input terminal of the operational amplifier D1 is connected to the voltage output terminal of the D/A2; D/A2 accepts the control The data transmitted by the controller; the ground terminal G of the gate driver 2 is connected to the common ground; the controller is connected to the temperature sensor;

The composition in the measurement mode includes: adjustable voltage source, MOS tube Q3, feedback resistor R and the device under test Q1 in series to form a loop; the adjustable constant current source is composed of MOS tube Q3, operational amplifier D2, and feedback resistor R; MOS tube The gate of Q3 is connected to the output end of the operational amplifier D2; the inverting input end of the operational amplifier D2 is connected to the source electrode of the MOS transistor Q3; one end of the voltage output end of D/A4 is connected to the non-inverting input end of the operational amplifier D2, and the other end Connect to the collector of the device under test Q1; D/A4 receives the data sent by the controller; the device under test is placed on the heat sink; the analog input end of A/D2 is connected to the collector and emitter of the device under test; A/ The analog input terminal of D3 is connected to both ends of the feedback resistor R; A/D2 and A/D3 receive the conversion start signal of the controller and transmit the data results of the analog-to-digital conversion to the controller; the gate and gate drive of the device under test The output terminal O of 1 is connected to the output terminal O of the gate driver 1; the ground terminal G of the gate driver 1 is connected to the output terminal of the operational amplifier D3; the control terminal of the gate driver 1 is connected to the controller; The non-inverting input terminal of operational amplifier D3 is connected to the collector of the device under test; the inverting input terminal of operational amplifier D3 is connected to the voltage output terminal of D/A3; D/A3 receives the data transmitted by the controller.

Wherein, use the power switch junction temperature calibration and heat dissipation component performance evaluation device based on the bias current dynamic pre-compensation method of the present invention for calibration and evaluation, including a calibration step and a measurement step;

Wherein, the calibration step includes:

Calibration step 1: Inject initial parameters: the heat capacity C _die of the device under test, the heat capacity of the heat storage block C _{heat storage block} , the constant current source bias current _IS , the thermal equilibrium transition time t _m , the temperature measurement list, the rated grid The pole voltage V _GE , the turn-on delay time t _d(on) of the device under test, the acquisition time ts _s of the saturated conduction voltage drop of the device under test, the maximum allowable junction temperature T _jmax of the device under test, and the voltage change threshold V _MAX of the switching device , the saturated conduction voltage drop value V _S of the device under test at the rated current, the predetermined value V _m of the voltage at both ends of the constant current source, and the temperature measurement error threshold T _e ;

Calibration step 2: put the heat storage block whose temperature is lower than the minimum value of the temperature measurement list item into the heat preservation container; take the value from the temperature measurement list item from low to high, denoted as T _m , and raise the internal temperature of the heat preservation container to Target temperature T _m ; the process of raising the temperature to the target temperature T _m is as follows: ① Measure the initial temperature T ₀ in the heat preservation container, set the bias current of the adjustable constant current source as I _S , and the controller output gate control signal is low level , the device under test is turned on, the duration is t, and the saturation conduction voltage drop V _ce is measured; the controller outputs the gate control signal as a high level, so that the device under test is turned off, after waiting time t _m , the under test When the junction and shell temperatures of the device are consistent, the temperature sensor measures the internal temperature T ₁ of the thermal insulation container at this time; by the formula C=(T ₁ -T ₀ )/V _ce *I _S *t, the heat capacity C in the thermal insulation container is calculated; ②According to Heat capacity C, target temperature T _m , calculate the turn-on time t ₁ of the device under test; turn the device under test on for a duration of t ₁ ; turn off the device under test, wait for the time t _m , and measure the inside of the thermal insulation container at this time temperature T _n ; ③ Judging that T _m -T _n <T _e , if it is less than T _e , the heating process ends; if it is greater than T _e , then return to step ② until it is less than T _e ;

Calibration step 3: The controller sends a high level to the control terminal of the gate driver 2 to turn on the accompanying load, and adjust the size of D/A2, so that the voltage V _B across the drain and source of the accompanying load is equal to V _S ;

Calibration step 4: adjust the voltage across the voltage source to make the voltage across the constant current source a predetermined value V _m ; adjust the bias current of the constant current source to be equal to I _S , wait for the bias current of the adjustable constant current source to stabilize; set D/A1 is equal to the rated gate voltage V _GE of the device under test; at the moment of τ ₀ , the controller outputs the gate control signal as a low level, which makes the device under test turn on and the load is turned off; at τ ₁ (τ ₀ + t _d(on) <τ ₁ <τ ₀ +t _s ), collect the value of _A /D1, denoted as VA; the controller outputs the gate control signal as high level, which makes the device under test turn on with the load. turn off;

Calibration Step 5: Judging |V _A -V _B |<V _MAX , if it is less than V _MAX , record the V _A value of the saturated conduction voltage drop of the device under test; if the absolute value of the difference is greater than V _MAX , set D/A2 , make the voltage _VB between the drain and source of the accompanying load equal to VA, and return to the calibration step _{4 until |V A -V B | <} V _MAX ;

Calibration step 6: determine whether the temperature list item value is completed, if completed, continue to the next step; if not completed, go back to calibration step 2;

Calibration step 7: Fit the measured data values of the saturated on-state voltage drop of the device under test at different junction temperatures into a relationship of T _j =f(V _CE );

The measurement steps include:

Measurement step 1: Inject initial parameters: DUT turn-on delay time t _d(on) , DUT saturation conduction voltage drop acquisition time _ts , DUT heating power list item, constant current source bias current I _S , the current error threshold I _e ;

Measurement step 2: take the value from the list item of the heating power of the device under test, denoted as P _i ;

Measurement step 3: Set the size of D/A4, make the constant current source bias current equal to _IS , and wait for the constant current source bias current to stabilize;

Measurement step 4: The controller outputs the gate control signal as low level, according to the formula V _D/A3 =P _i / _IS , set the size of D/A3, and wait for the thermal steady state;

Measurement step 5: At the moment of τ ₂ , the controller outputs the gate control signal as a high level; at the moment of τ ₃ (τ ₂ +t _d(on) <τ ₃ <τ ₂ +t _s ), the A/D2 and The value of A/D3 is denoted as V _CE and _IA respectively; the size of calculation formula ΔI _S =I _S -I _A ;

Measurement Step 6: Judging |ΔI _S |<I _e , if it is less than I _e , proceed to the next step; if it is greater than I _e , set the size of D/A4 to make the bias current of the adjustable constant current source equal to I _S +ΔI _S , wait for the bias current of the adjustable constant current source to stabilize, and return to measurement step 4;

Measurement step 7: Inversely infer the junction temperature T _j of the device under test from the relationship T _j =f(V _CE ) and the saturated conduction voltage drop V _CE value;

Measurement step 8: determine whether the value of the heating power list item is completed, if completed, continue to the next step; if not, return to measurement step 2;

Measurement Step 9: Obtain the junction temperature characteristics of the device under test under different heating powers.

Different from the prior art, the device for junction temperature calibration and heat dissipation component performance evaluation based on bias current pre-compensation of the present invention includes two working modes: calibration and measurement. The calibration mode is composed of the device under test under constant current source excitation and the accompanying load in parallel. The saturation conduction voltage drop of the device under test at different junction temperatures can be obtained, and the relationship between the junction temperature and the saturation conduction voltage drop can be obtained; , control the saturation conduction voltage drop to make the device under test work under different heating power, measure the saturation conduction voltage drop of the device under test, and inversely infer the junction temperature of the device under test according to the relationship between the junction temperature and the saturation conduction voltage drop, The junction temperature characteristics of the device under different heating power are obtained to evaluate the heat dissipation performance of the heat dissipation component.

Description of drawings

FIG. 1 is a circuit diagram of the device under test in the calibration mode of the present invention.

FIG. 2 is a circuit diagram of the present invention in the calibration mode with the load conducting.

FIG. 3 is a circuit diagram of the present invention in a measurement mode.

Figure 4 is a trend diagram of the output current of the constant current source as a function of the voltage at both ends thereof.

Figure 5 is a graph of the output characteristics of the device under test.

Figure 6 is a comparison chart of the calibration measurement results of the device under test under different test currents.

Figure 7 shows the RC thermal network model of the device in calibration mode.

Figure 8 is a graph showing the change of the junction and case temperature with time from the start of heating to the end of the steady state of the device in the Pspice environment.

Figure 9 is a graph showing the change of junction temperature with time at the beginning of heating of the device in the Pspice environment.

Figure 10 is a three-dimensional relationship diagram of junction temperature, saturated on-state voltage drop, and gate voltage fitted by Matlab.

Figure 11 is a flow chart of the calibration mode.

Figure 12 is a flow chart of the heating process in the calibration mode.

Figure 13 is a flow chart of the measurement mode.

Detailed ways

The technical solutions of the present invention will be further described in more detail below in conjunction with specific embodiments. Obviously, the described embodiments are only some, but not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

The testing device designed by the present invention is shown in Figures 1 , 2 and 3 . The device under test is an IGBT, the model is IKW40T120, the package is TO-247, the rated current is 40A, the maximum allowable junction temperature is 150℃, and the turn-on delay time is 52ns.

The present invention provides a junction temperature calibration and heat dissipation component performance evaluation device based on bias current pre-compensation. As shown in Figure 1, the device in the calibration mode is composed of: an adjustable voltage source, an adjustable constant current source and a measured The device Q1 is connected in series to form a loop; the negative electrode of the adjustable voltage source is the common ground; the device under test, the temperature sensor and the heat storage block are placed in a heat preservation container; the accompanying load Q2 is connected in parallel with the device under test Q1; the analog input terminal of A/D1 is connected to The collector and emitter of the device under test Q1 are connected; A/D1 receives the conversion start signal of the controller and transmits the data result of the analog-to-digital conversion to the controller; the gate of the device under test Q1 is connected to the output terminal of gate driver 1 O is connected to; the power supply terminal V of gate driver 1 is connected to D/A1; D/A1 receives the data transmitted by the controller; the gate control signal output by the controller is connected to the control terminal C of gate driver 2, and the gate control The signal is connected to the control terminal C of the gate driver 1 through the NOT gate; the ground terminal G of the gate driver 1 is connected to the common ground; the gate of the accompanying load Q2 is connected to the output terminal O of the gate driver 2; The power supply terminal V is connected to the output terminal of the operational amplifier D1; the non-inverting input terminal of the operational amplifier D1 is connected to the drain of the accompanying load Q2; the inverting input terminal of the operational amplifier D1 is connected to the voltage output terminal of D/A2; D/A2 Accept the data sent by the controller; the ground terminal G of the gate driver 2 is connected to the common ground; the controller is connected to the temperature sensor;

As shown in Figure 2, the composition of the device in the measurement mode includes: an adjustable voltage source, a MOS transistor Q3, a feedback resistor R and the device under test Q1 in series to form a loop; the adjustable constant current source consists of a MOS transistor Q3 and an operational amplifier D2 , feedback resistor R; the gate of MOS tube Q3 is connected to the output end of operational amplifier D2; the inverting input end of operational amplifier D2 is connected to the source of MOS tube Q3; one end of the voltage output end of D/A4 is connected to operational amplifier D2 The non-inverting input of A/D2 is connected to the non-inverting input, and the other end is connected to the collector of the device under test Q1; D/A4 receives the data sent by the controller; the device under test is placed on the heat sink; the analog input of A/D2 is connected to the collector of the device under test. The electrode and the emitter are connected; the analog input end of A/D3 is connected to both ends of the feedback resistor R; A/D2 and A/D3 receive the conversion start signal of the controller, and transmit the data result of the analog-to-digital conversion to the controller; the tested The gate of the device is connected to the output terminal O of the gate driver 1; the ground terminal G of the gate driver 1 is connected to the output terminal of the operational amplifier D3; the control terminal of the gate driver 1 is connected to the controller; the power supply of the gate driver 1 The terminal V is connected to the standard gate voltage power supply; the non-inverting input terminal of the operational amplifier D3 is connected to the collector of the device under test; the inverting input terminal of the operational amplifier D3 is connected to the voltage output terminal of D/A3; D/A3 receives the controller transmitted data.

In this embodiment, the constant current source provides the working current of the IGBT under test to be 40A of the rated current of the device under test.

According to the thermoelectric comparison theory, the thermal circuit parameters can be analogized to the circuit parameters, so the heat dissipation model of the IGBT can be analogized to the circuit shown in Figure 7. where P is the heating power, T _j is the junction temperature, Z _th-jc is the thermal resistance from the junction to the case, Z _th-ch is the thermal resistance from the case to the radiator, and Z _th-ha is the thermal resistance from the radiator to the ambient temperature , T _a is the ambient temperature.

Determination of thermal equilibrium transition time t _m : In the Pspice circuit simulation software, the RC thermal network model shown in Figure 4 is established. Check the manual of the IGBT under test, set the junction and case thermal resistance and thermal capacitance, and set the thermal resistance and thermal capacitance from the junction to the insulation layer and the insulation layer to the environment. Set the current source to pulse current source, the current peak value is 76A, the pulse width is 500us, the delay time is 10ms, and the voltage source voltage is set to 15V. Voltage probes are set at the junction temperature T _j and the case temperature T _c respectively, and the transient simulation analysis of the circuit is carried out. The simulation is performed under the condition of an ambient temperature of 15°C and a heating power of 76W. The variation trend of the shell temperature with time is shown in Figure 5. It can be seen from Figure 5 that the junction and case temperatures reach a steady-state value of 16.8°C at 120ms. Therefore, the transition time t _m to reach thermal equilibrium inside the thermal insulation layer is 110 ms, that is, the temperature sensor needs to start measuring the internal temperature of the thermal insulation layer at least 110 ms after the device under test is turned on.

Determination of saturation conduction voltage drop acquisition time t _s : Build the circuit in Figure 4 under the Pspice simulation software, set a voltage probe at the junction temperature T _j , conduct transient simulation analysis of the circuit, and simulate the device under test after the excitation is applied. , the junction temperature changes with time, and the simulation results are shown in Figure 6. It can be seen from Figure 6 that the junction temperature rises from 15°C to 16°C in 30.1us; the junction temperature rises from 16°C to 17°C in 31.6us; the junction temperature rises from 17°C to 18°C in 36.2us . After that, the junction temperature curve with time gradually flattened. Therefore, the acquisition time t _s of the saturated conduction voltage drop of the device under test needs to be within 30us to satisfy the junction temperature measurement error of less than 1°C.

Determination of the voltage change threshold V _MAX of the switching device: In the Pspice circuit simulation software, establish the constant current source circuit shown in Figure 7, set the voltage source V as a pulse voltage source, and the output steady _- state current of the constant current source is 40A. Place a current probe at the place, conduct transient analysis on the circuit, and simulate the change law of the bias current of the constant current source when the load is switched to the device under test. The simulation results are shown in Figure 8. It can be seen from Figure 8 that when the voltage across the constant current source changes stepwise by 0.1V, the bias current of the constant current source changes by 40mA at the 30us collection time of the saturated conduction voltage drop. Figure 9 is the output characteristic curve of the device under test. It can be seen from Figure 9 that when the collector-emitter current of the device under test changes by 40mA, the saturated on-state voltage drop changes by 1mV; Figure 10 shows the change curve of the device's saturation on-state voltage drop under a certain gate voltage under different junction temperatures. As can be seen from Figure 10, when the collector-emitter current of the device under test changes by 40mA and the saturated on-state voltage drop changes by 1mV, the calibration operating point will change from point A to point B, resulting in a 1°C change in the junction temperature of the device under test. Therefore, to ensure that the measurement error of the junction temperature of the device under test is within the range of 1°C, when the load is switched to the device under test, the voltage change between the two should not exceed 0.1V, that is, the threshold V _MAX of the load voltage change is 0.1V .

Determination of the constraints of the on-time t of the device under test: ①t≤(T _jmax -T ₀ )/C _die *I _S *V _S . ②t≤(T _jmax -T ₀ )/C _{heat storage block} *I _S *V _S . Take the minimum value of t in both ① and ② as the value range of t.

The invention provides a junction temperature calibration and heat dissipation component performance evaluation device based on bias current pre-compensation, the operation steps of which include the following calibration steps and measurement steps:

The flowchart of the calibration step is shown in Figure 11, including the steps:

Calibration step 1: Inject initial parameters: the heat capacity C _die of the device under test, the heat capacity of the heat storage block C _{heat storage block} , the constant current source bias current _IS , the thermal equilibrium transition time t _m , the temperature measurement list, the rated gate voltage V _GE , turn-on delay time t _d(on) of the device under test, acquisition time _ts of the saturated conduction voltage drop of the device under test, maximum allowable junction temperature T _jmax of the device under test, threshold V _MAX of the voltage change of the switching device, Under the rated current, the saturated conduction voltage drop value V _S of the device under test, the predetermined value V _m of the voltage across the constant current source, and the temperature measurement error threshold T _e .

Calibration step 2: Put the heat storage block whose temperature is lower than the minimum value of the temperature measurement list item into the heat preservation container. Take values from the temperature measurement list items from low to high, denoted as T _m , and raise the internal temperature of the heat preservation container to the target temperature T _m . Figure 12 shows a schematic diagram of the process of heating up to the target temperature T _m in the calibration mode. The process is as follows: ① Measure the initial temperature T ₀ in the heat preservation container, set the bias current of the constant current source to I _S , and control the output grid of the controller. When the signal is low, the device under test is turned on for a duration of t, and its saturation conduction voltage drop V _ce is measured. The controller outputs the gate control signal as high level to turn off the device under test. After waiting time _tm , the junction and case temperatures of the device under test reach the same level, and the temperature sensor measures the internal temperature T1 _of the heat preservation container. From the formula C=(T ₁ -T ₀ )/V _ce *I _S *t, the heat capacity C in the thermal insulation container is calculated. ②According to the heat capacity C and the target temperature T _m , calculate the turn-on time t ₁ of the device under test. Turn on the device under test for a duration of t ₁ . Turn off the device under test, and after waiting time t _m , measure the internal temperature T _n of the thermal insulation container at this time. ③ It is judged that T _m -T _n <T _e , if it is smaller than T _e , the heating process ends; if it is larger than T _e , return to step ② until it is smaller than T _e .

Calibration step 3: The controller sends a high level to the control terminal of the gate driver 2 to turn on the accompanying load, adjust the size of D/A2, and make the voltage V _B across the drain and source of the accompanying load equal to V _S .

Calibration step 4: Adjust the voltage across the voltage source so that the voltage across the constant current source is a predetermined value V _m . Adjust the constant current source bias current to be equal to I _S , and wait for the constant current source bias current to stabilize. Set D/A1 to be equal to the rated gate voltage V _GE of the device under test. At the moment of τ ₀ , the controller outputs the gate control signal to a low level, which makes the device under test turn on and the load is turned off; at the moment of τ ₁ (τ ₀ +52ns<τ ₁ <τ ₀ +30us), the A The value of /D1 is recorded as V _A . The controller outputs the gate control signal as a high level, which makes the device under test turn off with the load turned on.

Calibration Step 5: Judging |V _A -V _B |<0.1V, if it is less than 0.1V, record the saturated conduction voltage drop V _A value of the device under test; if the absolute value of the difference is greater than V _MAX , set D/A2 The output V _B is equal to V _A , and returns to calibration step four until |V _A - V _B | < 0.1V.

Calibration step 6: determine whether the temperature list item value is completed, if completed, continue to the next step; if not, go back to calibration step 2.

Calibration Step 7: Fit the measured data values of the saturated conduction voltage drop at different junction temperatures into the relationship of T _j = f(V _CE ). The relationship between the junction temperature and the saturated conduction voltage drop is shown in Figure 10 shown.

The flow chart of the measurement steps is shown in Figure 13, including the steps:

Measurement step 1: Inject initial parameters: DUT turn-on delay time t _d(on) , DUT saturation conduction voltage drop acquisition time _ts , DUT heating power list item, constant current source bias current I _S , the current error threshold I _e .

Measurement Step 2: Take the value from the list item of the heating power of the device under test, and record it as P _i .

Measurement Step 3: Set the size of D/A4 to make the constant current source bias current equal to _IS , and wait for the constant current source bias current to stabilize.

Measurement step 4: the controller outputs the gate control signal as low level, according to the formula V _D/A3 =P _i / _IS , set the size of D/A3, and wait for the thermal steady state.

Measurement Step 5: At the moment of τ ₂ , the controller outputs the gate control signal as a high level; at the moment of τ ₃ (τ ₂ +52ns<τ ₃ <τ ₂ +30us), collect the values of A/D2 and A/D3 , denoted as V _CE and _IA , respectively. Calculation formula ΔI _S =I _S -I _A size.

Measurement Step 6: Judging |ΔI _S |<I _e , if it is less than I _e , proceed to the next step; if it is greater than I _e , set the size of D/A4 to make the bias current of the adjustable constant current source equal to I _S +ΔI _S , wait for the constant current source bias current to stabilize, and return to measurement step 4.

Measurement step 7: Inversely infer the junction temperature T _j of the device under test from the relationship T _j =f(V _CE ) and the value of the saturated turn-on voltage drop V _CE .

Measurement step 8: determine whether the value of the heating power list item is completed, if completed, continue to the next step; if not, return to measurement step 2.

Measurement Step 9: Obtain the junction temperature characteristics of the device under test under different heating powers.

Different from the prior art, the device for junction temperature calibration and heat dissipation component performance evaluation based on bias current pre-compensation of the present invention includes two working modes: calibration and measurement. The calibration mode is composed of the device under test under constant current source excitation and the accompanying load in parallel. The saturation conduction voltage drop of the device under test at different junction temperatures can be obtained, and the relationship between the junction temperature and the saturation conduction voltage drop can be obtained; , control the saturation conduction voltage drop to make the device under test work under different heating power, measure the saturation conduction voltage drop of the device under test, and inversely infer the junction temperature of the device under test according to the relationship between the junction temperature and the saturation conduction voltage drop, The junction temperature characteristics of the device under different heating power are obtained to evaluate the heat dissipation performance of the heat dissipation component.

The above are only the embodiments of the present invention, and are not intended to limit the scope of the patent of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the description and drawings of the present invention, or directly or indirectly applied in other related technical fields, All are similarly included in the scope of patent protection of the present invention.

Claims (2)

1. a junction temperature calibration based on bias current pre-compensation and a heat dissipation component performance evaluation device, it is characterized in that, the composition under calibration mode comprises: adjustable voltage source, adjustable constant current source and device under test Q1 are connected in series to form a loop; The negative electrode of the adjustable voltage source is the common ground; the device under test, the temperature sensor and the heat storage block are placed in a heat preservation container; the accompanying load Q2 is connected in parallel with the device under test Q1; the analog input terminal of A/D1 is connected with the set of the device under test Q1. The electrode and the emitter are connected; A/D1 receives the conversion start signal of the controller, and transmits the data result of the analog-to-digital conversion to the controller; the gate of the device under test Q1 is connected to the output terminal O of the gate driver 1; the gate driver The power supply terminal V of 1 is connected to D/A1; D/A1 receives the data transmitted by the controller; the gate control signal output by the controller is connected to the control terminal C of gate driver 2, and the gate control signal passes through the NOT gate and the gate. The control terminal C of the gate driver 1 is connected to the control terminal C; the ground terminal G of the gate driver 1 is connected to the common ground; the gate of the accompanying load Q2 is connected to the output terminal O of the gate driver 2; the power terminal V of the gate driver 2 is connected to the operational amplifier The output terminal of D1 is connected; the non-inverting input terminal of the operational amplifier D1 is connected to the drain of the accompanying load Q2; the inverting input terminal of the operational amplifier D1 is connected to the voltage output terminal of D/A2; D/A2 accepts the data transmitted by the controller ; The ground terminal G of gate drive 2 is connected to the common ground; the controller is connected to the temperature sensor; The composition in the measurement mode includes: adjustable voltage source, MOS tube Q3, feedback resistor R and the device under test Q1 in series to form a loop; the adjustable constant current source is composed of MOS tube Q3, operational amplifier D2, and feedback resistor R; MOS tube The gate of Q3 is connected to the output end of the operational amplifier D2; the inverting input end of the operational amplifier D2 is connected to the source electrode of the MOS transistor Q3; one end of the voltage output end of D/A4 is connected to the non-inverting input end of the operational amplifier D2, and the other end Connect to the collector of the device under test Q1; D/A4 receives the data sent by the controller; the device under test is placed on the heat sink; the analog input end of A/D2 is connected to the collector and emitter of the device under test; A/ The analog input terminal of D3 is connected to both ends of the feedback resistor R; A/D2 and A/D3 receive the conversion start signal of the controller and transmit the data results of the analog-to-digital conversion to the controller; the gate and gate drive of the device under test The output terminal O of 1 is connected to the output terminal O of the gate driver 1; the ground terminal G of the gate driver 1 is connected to the output terminal of the operational amplifier D3; the control terminal of the gate driver 1 is connected to the controller; The non-inverting input terminal of operational amplifier D3 is connected to the collector of the device under test; the inverting input terminal of operational amplifier D3 is connected to the voltage output terminal of D/A3; D/A3 receives the data transmitted by the controller. 2. The device for junction temperature calibration and heat dissipation component performance evaluation based on bias current pre-compensation according to claim 1, wherein the execution step of the device comprises a calibration step and a measurement step; Wherein, the calibration step includes: Calibration step 1: Inject initial parameters: the heat capacity C _die of the device under test, the heat capacity of the heat storage block C _{heat storage block} , the constant current source bias current _IS , the thermal equilibrium transition time t _m , the temperature measurement list, the rated grid The pole voltage V _GE , the turn-on delay time t _d(on) of the device under test, the acquisition time ts _s of the saturated conduction voltage drop of the device under test, the maximum allowable junction temperature T _jmax of the device under test, and the voltage change threshold V _MAX of the switching device , the saturated conduction voltage drop value V _S of the device under test at the rated current, the predetermined value V _m of the voltage at both ends of the constant current source, and the temperature measurement error threshold T _e ; Calibration step 2: put the heat storage block whose temperature is lower than the minimum value of the temperature measurement list item into the heat preservation container; take the value from the temperature measurement list item from low to high, denoted as T _m , and raise the internal temperature of the heat preservation container to Target temperature T _m ; the process of raising the temperature to the target temperature T _m is as follows: ① Measure the initial temperature T ₀ in the heat preservation container, set the bias current of the adjustable constant current source as I _S , and the controller output gate control signal is low level , the device under test is turned on, the duration is t, and the saturation conduction voltage drop V _ce is measured; the controller outputs the gate control signal as a high level, so that the device under test is turned off, after waiting time t _m , the under test When the junction and shell temperatures of the device are consistent, the temperature sensor measures the internal temperature T ₁ of the thermal insulation container at this time; by the formula C=(T ₁ -T ₀ )/V _ce *I _S *t, the heat capacity C in the thermal insulation container is calculated; ②According to Heat capacity C, target temperature T _m , calculate the turn-on time t ₁ of the device under test; turn the device under test on for a duration of t ₁ ; turn off the device under test, wait for the time t _m , and measure the inside of the thermal insulation container at this time temperature T _n ; ③ Judging that T _m -T _n <T _e , if it is less than T _e , the heating process ends; if it is greater than T _e , then return to step ② until it is less than T _e ; Calibration step 3: The controller sends a high level to the control terminal of the gate driver 2 to turn on the accompanying load, and adjust the size of D/A2, so that the voltage V _B across the drain and source of the accompanying load is equal to V _S ; Calibration step 4: adjust the voltage across the voltage source to make the voltage across the constant current source a predetermined value V _m ; adjust the bias current of the constant current source to be equal to I _S , wait for the bias current of the adjustable constant current source to stabilize; set D/A1 is equal to the rated gate voltage V _GE of the device under test; at the moment of τ ₀ , the controller outputs the gate control signal as a low level, which makes the device under test turn on and the load is turned off; at τ ₁ (τ ₀ + t _d(on) <τ ₁ <τ ₀ +t _s ), collect the value of _A /D1, denoted as VA; the controller outputs the gate control signal as high level, which makes the device under test turn on with the load. turn off; Calibration Step 5: Judging |V _A -V _B | < V _MAX , if it is less than V _MAX , record the saturated conduction voltage drop V _A value of the device under test; if the absolute value of the difference is greater than V _MAX , set D/A2 , make the voltage _VB between the drain and source of the accompanying load equal to VA, and return to the calibration step _{4 until |V A -V B | <} V _MAX ; Calibration step 6: determine whether the temperature list item value is completed, if completed, continue to the next step; if not completed, go back to calibration step 2; Calibration step 7: Fit the measured data values of the saturated on-state voltage drop of the device under test at different junction temperatures into a relationship of T _j =f(V _CE ); The measurement steps include: Measurement step 1: Inject initial parameters: DUT turn-on delay time t _d(on) , DUT saturation conduction voltage drop acquisition time _ts , DUT heating power list item, constant current source bias current I _S , the current error threshold I _e ; Measurement step 2: take the value from the list item of the heating power of the device under test, denoted as P _i ; Measurement step 3: Set the size of D/A4, make the constant current source bias current equal to _IS , and wait for the constant current source bias current to stabilize; Measurement step 4: The controller outputs the gate control signal as low level, according to the formula V _D/A3 =P _i / _IS , set the size of D/A3, and wait for the thermal steady state; Measurement step 5: At the moment of τ ₂ , the controller outputs the gate control signal as a high level; at the moment of τ ₃ (τ ₂ +t _d(on) <τ ₃ <τ ₂ +t _s ), the A/D2 and The value of A/D3 is denoted as V _CE and _IA respectively; the size of calculation formula ΔI _S =I _S -I _A ; Measurement Step 6: Judging |ΔI _S |<I _e , if it is less than I _e , proceed to the next step; if it is greater than I _e , set the size of D/A4 to make the bias current of the adjustable constant current source equal to I _S +ΔI _S , wait for the bias current of the adjustable constant current source to stabilize, and return to measurement step 4; Measurement step 7: Inversely infer the junction temperature T _j of the device under test from the relationship T _j =f(V _CE ) and the saturated conduction voltage drop V _CE value; Measurement step 8: determine whether the value of the heating power list item is completed, if completed, continue to the next step; if not, return to measurement step 2; Measurement Step 9: Obtain the junction temperature characteristics of the device under test under different heating powers.

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