Test circuit and method for intelligent power module

Abstract

The embodiment of the invention provides a test circuit and method for an intelligent power module, the intelligent power module comprises an insulated gate bipolar transistor, the test circuit comprises a voltmeter, a first fast diode, a first switch and a current input circuit, and the voltmeter, the first fast diode and the first switch are connected in series; the insulated gate bipolar transistor is connected in parallel with a series circuit of the voltmeter, the first fast diode and the first switch; the current input circuit is connected with a series circuit of the voltmeter, the first fast diode and the first switch. Under the condition that the intelligent power module is switched from the working state to the test state, the first fast diode delays conduction to influence the delay time of the voltmeter for measuring the forward voltage drop of the insulated gate bipolar transistor, so that the noise caused by the switching of the intelligent power module from the working state to the test state is filtered; and the test result is more accurate.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor device testing, and in particular to a testing circuit and method for an intelligent power module. Background Art

[0002] In the field of electronics and electrical, the testing of intelligent power modules is very important, among which, accurate measurement of the thermal resistance of the device is crucial. Thermal resistance reflects the ease with which the device dissipates heat during operation, and plays a key role in ensuring the reliability, stability and service life of the device. For example, in power semiconductor devices, excessive thermal resistance may cause the device temperature to be too high, causing performance degradation, failure or even damage. However, traditional testing methods for intelligent power modules are difficult to obtain accurate test results due to factors such as interference from the test environment and errors in the measurement equipment. Summary of the invention

[0003] In view of the above problems, embodiments of the present invention are proposed to provide a test circuit and method for an intelligent power module that overcomes the above problems or at least partially solves the above problems.

[0004] In order to solve the above problems, an embodiment of the present invention discloses a test circuit of an intelligent power module, wherein the intelligent power module includes an insulated gate bipolar transistor, and the test circuit includes a voltmeter, a first fast diode, a first switch and a current input circuit;

[0005] The voltmeter, the first fast diode and the first switch are connected in series;

[0006] The insulated gate bipolar transistor is connected in parallel with a series circuit of the voltmeter, the first fast diode and the first switch;

[0007] The current input circuit is connected to a series circuit of the voltmeter, the first fast diode and the first switch;

[0008] When the insulated gate bipolar transistor is configured to be turned on, the first switch is configured to be turned off, and the intelligent power module is in an operating state, the current input circuit is used to provide a heating current and a test current in a first current flow direction;

[0009] When the insulated gate bipolar transistor is configured to be turned on, the first switch is configured to be closed, and the intelligent power module is switched from the working state to the test state, the current input circuit is used to provide a test current in a first current flow direction so as to delay the turn-on of the first fast diode; and the voltmeter is used to measure the forward voltage drop of the insulated gate bipolar transistor after the first fast diode is turned on.

[0010] Optionally, the current input circuit includes a second switch; a first end of the second switch is connected to the first switch, a second end is connected to the first current source, and a third end is connected to the second current source; the first current source is used to provide a heating current, and the second current source is used to provide a test current;

[0011] When the intelligent power module is in working state, the second end and the third end of the second switch are closed; when the intelligent power module is switched from the working state to the test state, the second end of the second switch is disconnected and the third end of the second switch is closed.

[0012] Optionally, the first fast diode is a unidirectional conducting diode; the conducting direction of the first fast diode is the same as the first current flow direction of the test current provided by the current input circuit.

[0013] Optionally, the intelligent power module also includes a second fast diode; the second fast diode is arranged between the collector and the emitter of the insulated gate bipolar transistor; and the conduction direction of the second fast diode in the insulated gate bipolar transistor is opposite to the conduction direction of the insulated gate bipolar transistor.

[0014] Optionally, when the insulated gate bipolar transistor is configured to be cut off so that the second fast diode is turned on, the first switch is configured to be disconnected, and when the intelligent power module is in a working state, the current input circuit is used to provide a heating current and a test current in a second current flow direction; the first current flow direction is opposite to the second current flow direction;

[0015] When the insulated gate bipolar transistor is configured to be cut off, the first switch is configured to be closed, and the intelligent power module is switched from the working state to the test state, the current input circuit is used to provide a test current in the second current flow direction to cut off the first fast diode and turn on the second fast diode; the voltmeter is used to measure the voltage of the second fast diode after the second fast diode is turned on.

[0016] Optionally, when the insulated gate bipolar transistor is configured to be turned on so that the second fast diode is turned off, the first switch is configured to be turned off, and when the intelligent power module is in a working state, the current input circuit is used to provide a heating current and a test current in the first current flow direction;

[0017] When the insulated gate bipolar transistor is configured to be turned on so that the second fast diode is cut off, the first switch is configured to be closed, and when the intelligent power module is switched from the working state to the test state, the current input circuit is used to provide a test current in a first current flow direction so that the first fast diode is delayed in turning on; and the voltmeter is used to measure the forward voltage drop of the insulated gate bipolar transistor after the first fast diode is turned on.

[0018] Accordingly, an embodiment of the present invention discloses a method for testing an intelligent power module, which involves the test circuit as described above. The method includes:

[0019] Obtaining a forward voltage drop of the insulated gate bipolar transistor measured by the voltmeter after the first fast diode is turned on;

[0020] Determining a first relationship coefficient between a forward voltage drop and temperature of an insulated gate bipolar transistor;

[0021] determining a first target temperature corresponding to the measured forward voltage drop of the insulated gate bipolar transistor according to the first relationship coefficient;

[0022] A thermal resistance of the insulated gate bipolar transistor is determined according to the first target temperature.

[0023] Optionally, determining the thermal resistance of the insulated gate bipolar transistor according to the first target temperature includes:

[0024] Determining a first power difference generated when the intelligent power module is switched from the working state to the testing state;

[0025] A thermal resistance of the insulated gate bipolar transistor is determined according to the first power difference and the first target temperature.

[0026] Optionally, the intelligent power module further includes a second fast diode, and the method further includes:

[0027] obtaining a voltage of the second fast diode measured by the voltmeter after the second fast diode is turned on;

[0028] determining a second coefficient of relationship between voltage and temperature of a second fast diode;

[0029] determining, according to the second relationship coefficient, a second target temperature corresponding to the measured forward voltage drop of the second fast diode;

[0030] According to the second target temperature, a thermal resistance of the second fast diode is determined.

[0031] Optionally, determining the thermal resistance of the second fast diode according to the second target temperature includes:

[0032] Determining a second power difference generated when the intelligent power module is switched from the working state to the testing state;

[0033] A thermal resistance of the second fast diode is determined according to the second power difference and the second target temperature.

[0034] The embodiments of the present invention include the following advantages:

[0035] The test circuit of the intelligent power module of the embodiment of the present invention comprises an insulated gate bipolar transistor, and the test circuit comprises a voltmeter, a first fast diode, a first switch and a current input circuit, wherein the voltmeter, the first fast diode and the first switch are connected in series; the insulated gate bipolar transistor is connected in parallel with the series circuit of the voltmeter, the first fast diode and the first switch; the current input circuit is connected with the series circuit of the voltmeter, the first fast diode and the first switch; when the insulated gate bipolar transistor is configured to be turned on, the first switch is configured to be turned off, and the intelligent power module is in a working state, the current input circuit is used to provide a heating current and a test current in a first current flow direction; when the insulated gate bipolar transistor is configured to be turned on, the first switch is configured to be closed, and the intelligent power module is switched from a working state to a test state, the current input circuit is used to provide a test current in a first current flow direction so as to delay the turn-on of the first fast diode; the voltmeter is used to measure the forward voltage drop of the insulated gate bipolar transistor after the first fast diode is turned on. When the intelligent power module switches from a working state to a test state, the first fast diode is delayed for conduction to affect the delay time of the voltmeter measuring the forward voltage drop of the insulated gate bipolar transistor, thereby screening out the noise caused by the intelligent power module switching from a working state to a test state, making the test result more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a structural diagram of a test circuit of an intelligent power module according to an embodiment of the present invention;

[0037] Figure 2 is a structural diagram of another test circuit of an intelligent power module according to an embodiment of the present invention;

[0038] Figure 3 is a structural diagram of another test circuit of an intelligent power module according to an embodiment of the present invention;

[0039] Figure 4 The present invention is a flowchart of a method for testing an intelligent power module according to an embodiment of the present invention.

[0040] Figure numerals: intelligent power module 10, insulated gate bipolar transistor 11, second fast diode 12, high voltage integrated circuit 13, test circuit 20, voltmeter 21, first fast diode 22, first switch 23, current input circuit 24, second switch 241, first current source 242, second current source 243. DETAILED DESCRIPTION

[0041] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0042] In the field of electronics and electrical, the testing of intelligent power modules is very important, among which, accurate measurement of the thermal resistance of the device is crucial. Thermal resistance reflects the ease with which the device dissipates heat during operation, and plays a key role in ensuring the reliability, stability and service life of the device. For example, in power semiconductor devices, excessive thermal resistance may cause the device temperature to be too high, causing performance degradation, failure or even damage. However, traditional testing methods for intelligent power modules are difficult to obtain accurate test results due to factors such as interference from the test environment and errors in the measurement equipment.

[0043] One of the core concepts of an embodiment of the present invention is that, when the intelligent power module switches from a working state to a test state, the first fast diode is delayed for conduction to affect the delay time of a voltmeter measuring a forward voltage drop of an insulated gate bipolar transistor, thereby filtering out noise caused by the intelligent power module switching from a working state to a test state, making the test result more accurate.

[0044] Reference Figure 1 , shows a structural diagram of a test circuit of an intelligent power module according to an embodiment of the present invention, which may specifically include the following structure:

[0045] The intelligent power module 10 includes an insulated gate bipolar transistor 11 , and the test circuit 20 includes a voltmeter 21 , a first fast diode 22 , a first switch 23 and a current input circuit 24 .

[0046] The voltmeter 21, the first fast diode 22 and the first switch 23 are connected in series.

[0047] The insulated gate bipolar transistor 11 is connected in parallel to a series circuit of a voltmeter 21 , a first fast diode 22 and a first switch 23 .

[0048] Exemplarily, the emitter of the insulated gate bipolar transistor 11 is connected to the voltmeter 21 , the collector of the insulated gate bipolar transistor 11 is connected to the first switch 23 , and the first fast diode 22 is disposed between the first switch 23 and the voltmeter 21 .

[0049] The current input circuit 24 is connected to a series circuit of the voltmeter 21 , the first fast diode 22 , and the first switch 23 .

[0050] When the insulated gate bipolar transistor 11 is configured to be turned on, the first switch 23 is configured to be turned off, and the intelligent power module 10 is in operation, the current input circuit 24 is used to provide a heating current and a test current in a first current direction.

[0051] The working state may also be called a heating state, which means that a heating current and a test current pass through the insulated gate bipolar transistor 11 at the same time.

[0052] When the insulated gate bipolar transistor 11 is configured to be turned on, the first switch 23 is configured to be closed, and when the intelligent power module 10 is switched from the working state to the test state, the current input circuit 24 is used to provide a test current in the first current flow direction so that the first fast diode 22 is delayed to be turned on; the voltmeter 21 is used to measure the forward voltage drop of the insulated gate bipolar transistor 11 after the first fast diode is turned on.

[0053] The test circuit of the intelligent power module of the embodiment of the present invention comprises an insulated gate bipolar transistor, and the test circuit comprises a voltmeter, a first fast diode, a first switch and a current input circuit, wherein the voltmeter, the first fast diode and the first switch are connected in series; the insulated gate bipolar transistor is connected in parallel with the series circuit of the voltmeter, the first fast diode and the first switch; the current input circuit is connected with the series circuit of the voltmeter, the first fast diode and the first switch; when the insulated gate bipolar transistor is configured to be turned on, the first switch is configured to be turned off, and the intelligent power module is in a working state, the current input circuit is used to provide a heating current and a test current in a first current flow direction; when the insulated gate bipolar transistor is configured to be turned on, the first switch is configured to be closed, and the intelligent power module is switched from a working state to a test state, the current input circuit is used to provide a test current in a first current flow direction so as to delay the turn-on of the first fast diode; the voltmeter is used to measure the forward voltage drop of the insulated gate bipolar transistor after the first fast diode is turned on. When the intelligent power module switches from a working state to a test state, the first fast diode is delayed for conduction to affect the delay time of the voltmeter measuring the forward voltage drop of the insulated gate bipolar transistor, thereby screening out the noise caused by the intelligent power module switching from a working state to a test state, making the test result more accurate.

[0054] Reference Figure 2, shows a structural diagram of a test circuit of an intelligent power module according to an embodiment of the present invention, wherein the current input circuit 24 includes a second switch 241; the first end of the second switch 241 is connected to the first switch 23, the second end is connected to the first current source 242, and the third end is connected to the second current source 243; the first current source 242 is used to provide a heating current, and the second current source 243 is used to provide a test current.

[0055] When the intelligent power module 10 is in working state, the second end and the third end of the second switch 241 are closed, and the second switch 241 is connected to the test current Imeas (IM) and the heating current Iheat (IH) at the same time. Figure 2 In the figure, IF represents the current from the collector (C) to the emitter (E) of the insulated gate bipolar transistor 11, and IF is equal to the test current plus the heating current. The collector-emitter voltage VF of the insulated gate bipolar transistor 11 is the forward voltage drop of the insulated gate bipolar transistor 11 measured by the voltmeter 21.

[0056] When the intelligent power module 10 switches from the working state to the testing state, the second end of the second switch 241 is disconnected, the third end of the second switch is closed, and the second switch 241 is only connected to the testing current.

[0057] Exemplarily, one end of the first current source 242 and the second current source 243 is connected to the second switch 241 , and the other end is connected to the voltmeter 21 .

[0058] In the embodiment of the present invention, the first fast diode 22 is a unidirectional conducting diode; the conducting direction of the first fast diode 22 is the same as the first current flow direction of the test current provided by the current input circuit 24 .

[0059] Exemplarily, the anode of the first fast diode 22 is connected to the first switch 23, and the cathode of the first fast diode 22 is connected to the voltmeter 21. When the current flows from the first switch 23 to the voltmeter 21, the first fast diode 22 is turned on. One end of the first current source 242 is connected to the voltmeter 21, and the other end is connected to the second switch 241. The current of the first current source 242 flows from the first current source 242 to the second switch 241. When the connection end of the second switch 241 and the first current source 242 is closed, the test current flows from the first current source 242 to the second switch 241. The first switch 23 is connected to the second switch 241. When the first switch 23 is closed, the first fast diode 22 is turned on.

[0060] In an embodiment of the present invention, the intelligent power module 10 also includes a high-voltage integrated circuit 13, the gate of the insulated gate bipolar transistor 11 is connected to the high-voltage integrated circuit 13, the high-voltage integrated circuit 13 is powered by Vcc (power supply voltage), the VIN port provides a PWN (Pulse Width Modulation) signal, and the conduction of the insulated gate bipolar transistor 11 is controlled through the HO (High-side Output) port.

[0061] The intelligent power module 10 also includes a bootstrap diode (DBOOT), a bootstrap capacitor (CBOOT) and a gate resistor (RG). The bootstrap diode is used in the bootstrap circuit to ensure that the bootstrap capacitor can be charged when the switch device is turned off, thereby providing the required voltage for the drive circuit on the high-voltage side. The bootstrap capacitor is used to store charge to provide the required voltage for the drive circuit on the high-voltage side. The gate resistor is used to control the gate current of the power semiconductor device, thereby adjusting the switching speed and driving capability of the device.

[0062] In the embodiment of the present invention, the intelligent power module 10 further includes a second fast diode 12 ; the second fast diode 12 is arranged between the collector and the emitter of the insulated gate bipolar transistor 11 ; and the conduction direction of the insulated gate bipolar transistor 11 is opposite to the conduction direction of the insulated gate bipolar transistor 11 .

[0063] The second fast diode 12 is arranged between the collector and the emitter of the insulated gate bipolar transistor 11, that is, the second fast diode 12 is connected in parallel with the insulated gate bipolar transistor 11, the anode of the second fast diode 12 is connected to the emitter of the second fast diode 12, and the cathode of the second fast diode 12 is connected to the collector of the second fast diode 12. When the insulated gate bipolar transistor 11 is turned on, the current flows from the collector of the insulated gate bipolar transistor 11 to the emitter of the insulated gate bipolar transistor 11, that is, from the cathode of the second fast diode 12 to the anode, and the second fast diode 12 is turned off. When the insulated gate bipolar transistor 11 is turned off, the current flows from the anode of the second fast diode 12 to the cathode, and the second fast diode 12 is turned on.

[0064] The main functions of the second fast diode 12 are as follows: reverse current recovery. When the insulated gate bipolar transistor 11 is turned off, the inductance in the load will generate a reverse current to try to maintain the current flow. The fast diode provides a low impedance path so that the reverse current can pass quickly, thereby reducing the reverse voltage stress on the insulated gate bipolar transistor 11; the fast recovery characteristics of the fast diode ensure that the reverse current can quickly recover to zero, reducing switching losses and electromagnetic interference; protecting the insulated gate bipolar transistor 11. When the insulated gate bipolar transistor 11 is turned off, if there is no fast diode, the reverse current may generate an excessively high voltage spike on the insulated gate bipolar transistor 11, causing damage to the insulated gate bipolar transistor 11. The fast diode provides a protection path to prevent excessive voltage spikes; improving system efficiency. The fast recovery characteristics of the fast diode can reduce switching losses and improve the overall efficiency of the system.

[0065] In an embodiment of the present invention, when the insulated gate bipolar transistor 11 is configured to be cut off so that the second fast diode 12 is turned on, the first switch 23 is configured to be disconnected, and when the intelligent power module 10 is in a working state, the current input circuit 24 is used to provide a heating current and a test current in the second current flow direction; the first current flow direction is opposite to the second current flow direction.

[0066] When the insulated gate bipolar transistor 11 is configured to be cut off, the first switch 23 is configured to be closed, and the intelligent power module 10 is switched from the working state to the test state, the current input circuit 24 is used to provide a test current in the second current flow direction to cut off the first fast diode 22 and turn on the second fast diode 12; the voltmeter 21 is used to measure the voltage of the second fast diode 12 after the second fast diode 12 is turned on.

[0067] When measuring the voltage of the second fast diode 12 , the first fast diode 22 and the first switch 23 connected in series may be disposed between the collector of the insulated gate bipolar transistor 11 and the voltmeter 21 , or between the emitter of the insulated gate bipolar transistor 11 and the voltmeter 21 .

[0068] In an embodiment of the present invention, when the insulated gate bipolar transistor 11 is configured to be turned on so that the second fast diode 12 is cut off, the first switch 23 is configured to be disconnected, and when the intelligent power module 10 is in a working state, the current input circuit 24 is used to provide heating current and test current in the first current flow direction.

[0069] When the insulated gate bipolar transistor 11 is configured to be turned on so that the second fast diode 12 is cut off, the first switch 23 is configured to be closed, and when the intelligent power module 10 is switched from the working state to the test state, the current input circuit 24 is used to provide a test current in the first current flow direction so that the first fast diode 22 is delayed to be turned on; the voltmeter 21 is used to measure the forward voltage drop of the insulated gate bipolar transistor 11 after the first fast diode 22 is turned on.

[0070] Reference Figure 4 , shows a flowchart of a method for testing an intelligent power module according to an embodiment of the present invention, which may specifically include the following steps:

[0071] Step 101, obtaining a forward voltage drop of the insulated gate bipolar transistor measured by the voltmeter after the first fast diode is turned on.

[0072] Step 102: determine a first relationship coefficient between a forward voltage drop of an insulated gate bipolar transistor and temperature.

[0073] Step 103: determining a first target temperature corresponding to the measured forward voltage drop of the insulated gate bipolar transistor according to the first relationship coefficient.

[0074] Step 104: determining a thermal resistance of the insulated gate bipolar transistor according to the first target temperature.

[0075] Specifically, the junction-to-case thermal resistance is a parameter that measures the heat diffusion capability of a semiconductor device from the chip surface to the package surface, where the package surface is in contact with the heat sink. The package surface usually refers to the shell or heat sink of a power semiconductor device (such as IGBT, MOSFET, etc.), which is usually made of materials with good thermal conductivity, such as copper or aluminum. The heat sink is a metal structure with a large area of ​​heat dissipation surface, which is usually installed near the package surface of the power device. The heat sink is designed to maximize the heat dissipation area and dissipate the heat to the surrounding environment through natural convection, forced air cooling or liquid cooling. By contacting the package surface with the heat sink, the heat generated by the power device is conducted to the heat sink through the package surface, and the heat sink dissipates the heat to the surrounding environment through its large area of ​​heat dissipation surface. JESD51-1 defines the junction-to-case thermal resistance as the thermal resistance from the heat source to the shell surface closest to the chip peak area when the semiconductor device shell is in good contact with the heat sink to minimize its surface temperature change.

[0076] The traditional thermocouple measurement method given in the MIL833 standard requires the determination of the junction temperature Tj, case temperature Tc, and heat dissipation power PH, and the device case is in good contact with the heat sink. The junction-to-case thermal resistance is calculated using the following formula:

[0077]

[0078] θJC refers to the steady-state thermal resistance because it is obtained under steady-state conditions and it depends on the junction-case temperature difference on the heat flow path. The junction temperature Tj refers to the temperature of the PN junction (or Schottky junction) in a semiconductor device. The PN junction is the core part of semiconductor devices, such as diodes, transistors, IGBTs, etc., and its performance and reliability are directly affected by the junction temperature. The difficulty of this measurement method is that it is difficult to accurately measure the case temperature of the package with a thermocouple when the case is in close contact with the heat sink. Therefore, different measurement equipment may obtain different θJC values.

[0079] In contrast, the method described in the embodiment of the present invention uses different cooling conditions on the heat sink surface and is a transient test based only on the junction temperature. It does not require the shell temperature Tc, thus eliminating the error introduced by Tc. The method only depends on the measurement of the junction temperature and does not require a lot of pressure to ensure good thermal contact with the heat sink.

[0080] Transient Double Interface (TDI) testing is a test method used to evaluate the thermal performance of semiconductor devices under transient conditions. TDI testing is mainly used to measure the thermal resistance and thermal capacitance of semiconductor devices under rapid thermal change conditions, thereby evaluating the thermal stability and reliability of the device. The basic principle of TDI testing is to apply a transient heat pulse between two different interfaces (usually the junction and the shell) of a semiconductor device, measure the time and temperature response of the heat pulse propagating inside the device, and thus calculate the thermal resistance and thermal capacitance of the device.

[0081] When constant power PH is applied to the semiconductor device at t = 0, and the housing is in good contact with the heat sink, the thermal impedance of the device is defined as follows:

[0082]

[0083] That is, thermal impedance is equal to the change in junction temperature Tj(t) over time divided by the heat dissipation power. Even if the cooling conditions of the housing change, it will have no effect on the thermal impedance unless the housing in contact with the heat sink starts to heat up. If the contact thermal resistance is different for each measurement, the steady-state total thermal resistance will also be different, so the thermal impedance curves under different measurements will separate from the contribution point of the contact thermal resistance on the housing surface.

[0084] In the transient test method, two thermal impedance measurements with different contact thermal resistances can determine the housing surface in contact with the heat sink. The thermal resistance at the separation point between the two measurements is defined as R θJC (θ JC ).

[0085] Junction temperature test: Measure the junction temperature (TJ) of the device under test (DUT) according to the method described in JESD51-1, and collect Z after removing the heating power PH. θJCCurve (cooling curve). The temperature sensitive parameter (TSP) in the test will not be affected by the heating voltage and heating current, and there is no need to control the size of the heating power. This test method is suitable for most devices and thermal test chips. θJC Before drawing a curve, you must first determine its K factor, which is the relationship coefficient between the chip temperature and the temperature sensitive parameter (voltage VF).

[0086] Recording of transient cooling curve: First, apply a constant heating current IH to the device under test to heat it and reach a thermally stable state, that is, the junction temperature of the chip remains unchanged. When the device reaches thermal stability, record the final heating voltage VH and heating current IH, cut off the heating current or switch the current to the test current IM, which will produce a large power difference ΔPH. Usually IM is very small compared to IH and can be ignored, and the power generated by the test current IM can also be ignored. However, the test principle requires accurate knowledge of the power difference ΔPH. In other words, if the thermal power consumption of the device takes into account PM (power consumption generated by IM current), this method will be more accurate. The larger the heating power difference ΔPH = PH-PM, the greater the signal-to-noise ratio (SNR) of the test, and the more accurate the thermal resistance (θJC) obtained.

[0087] The use of a thermal resistance tester can record the transient change process of junction temperature (including the heating process and the cooling process). In one test, both the steady-state junction-to-shell thermal resistance data and the transient curve of the junction temperature changing with time can be obtained. It can be used to test the thermal characteristics of common semiconductor thyristors, bipolar transistors, and high-power IGBTs, LEDs (Light Emitting Diodes) and other devices. The test circuit 20 and the intelligent power module 10 of the embodiment of the present invention are both applied to the intelligent power module of the thermal resistance tester. The heating current and the test current are provided by the thermal resistance tester equipment.

[0088] The double interface separation method is the core test method of this thermal resistance tester. The double interface separation method is a core test method for measuring the thermal impedance of semiconductor devices. This method applies a transient heat pulse between two different interfaces of the semiconductor device (usually the junction and the shell), measures the time and temperature response of the heat pulse propagating inside the device, and thus calculates the thermal impedance of the device. The basic principle of the double-interface separation method: transient heat pulse application, applying a transient heat pulse on one interface of the device (such as the junction), usually achieved by a current pulse or a laser pulse. The heat pulse will propagate inside the device, causing temperature changes; temperature response measurement, measuring the temperature response at another interface (such as the housing), usually using a thermocouple or infrared thermometer, by measuring the time and amplitude of the temperature response, the thermal impedance of the device can be calculated; thermal impedance calculation, thermal impedance (Zθ(t)) represents the relationship between the change in junction temperature (Tj(t)) of the device over time and the heat dissipation power (P(t)) under transient thermal conditions, and the calculation formula is: thermal impedance (Zθ(t)) equals the change in junction temperature (Tj(t)) over time / heat dissipation power (P(t)).

[0089] The separation method is a new method for testing thermal resistance based on the thermal parameter method. The thermal parameter method is a technology used to evaluate and measure the thermal performance of semiconductor devices. This method derives the thermal parameters of the device, such as thermal resistance, thermal capacitance and thermal time constant, by measuring the electrical performance parameters of the device under different temperature conditions, such as voltage, current, resistance, etc. The basic principle of the thermal parameter method: temperature dependence, the electrical performance parameters of semiconductor devices (such as voltage, current, resistance, etc.) are usually temperature dependent. By measuring the changes of these parameters at different temperatures, the thermal performance parameters of the device can be derived; thermal resistance and thermal capacitance, thermal resistance (Rθ) represents the thermal resistance from junction to shell, and the calculation formula is: Rθ=ΔT / Q, where ΔT is the temperature change and Q is the heat dissipation power; thermal capacitance (Cθ) represents the thermal capacitance of the device, and the calculation formula is: Cθ=Q / ΔT, where Q is the heat dissipation power and ΔT is the temperature change; thermal time constant, the thermal time constant (τ) represents the thermal response time of the device, which is usually determined by measuring the time constant of temperature change.

[0090] When measuring the thermal resistance of semiconductor devices, the thermistor method is usually divided into two main states: working state and test state. These two states are used to simulate the actual working conditions of the device and measure thermal performance parameters. The working state refers to the state of the semiconductor device under actual working conditions. In this state, the device is under normal working current and voltage conditions, and the heat generated is consistent with the situation in actual application. In the working state, the current and voltage of the device are set to the values ​​under actual working conditions. This is usually achieved by applying specific current and voltage to simulate the working state of the device in actual application. In the working state, the device will generate heat, and its heat generation rate is consistent with the situation in actual application. By measuring the power loss of the device (P=V×I), the heat generation rate of the device can be estimated. In the working state, the temperature of the device will gradually increase until it reaches a thermal equilibrium state. The thermal equilibrium state means that the temperature of the device no longer changes significantly, and the heat generation rate is equal to the heat dissipation rate.

[0091] The test state refers to the state where the thermal performance parameters are measured after the device reaches a thermal equilibrium state. In this state, the device's thermal resistance, thermal capacitance, thermal time constant and other thermosensitive parameters are derived by measuring the device's electrical performance parameters and temperature response. In the test state, the device's electrical performance parameters, such as voltage, current, resistance, etc., are measured. These parameters are usually temperature-dependent. By measuring the changes in these parameters at different temperatures, the device's thermal performance parameters can be derived. In the test state, a thermocouple or infrared thermometer is used to measure the device's temperature response, and the time and amplitude of the temperature response are recorded to calculate the thermal resistance, thermal capacitance and thermal time constant. Based on the measured electrical performance parameters and temperature response data, the device's thermal resistance, thermal capacitance and thermal time constant are calculated, the change trend of these thermosensitive parameters is analyzed, and the thermal stability and reliability of the device are evaluated.

[0092] When switching from the working state to the test state, the heating current must be cut off by a fast switching circuit, and the test current is added to the device to measure the junction voltage at this time to determine the corresponding temperature. The conversion delay time of the measuring device from the working state to the test state is 3 to 5us, so if the temperature corresponding to the measurement moment is directly used as the steady-state junction temperature, errors will inevitably occur.

[0093] In the embodiment of the present invention, before the voltage meter 21 detects, the first fast diode 22 is connected in series, and its delay time is within 3 to 5us. Sic (Silicon Carbide) or GaN (Gallium Nitride) diodes can be selected. The delay time of the voltage meter 21 collecting VF is affected by the turn-on delay time of the diode. The high-voltage integrated circuit 13 is powered by Vcc and provides a signal by VIN. The insulated gate bipolar transistor 11 is turned on through the chip. At the same time, the voltage meter 21 monitors the collector and emitter voltages VF of the insulated gate bipolar transistor 11. The second switch 241 controls the switching of the working state and the test state. When the intelligent power module 10 is in the working state, the second switch 241 is connected to the Imeas and Iheat current outputs at the same time; when the intelligent power module 10 is switched to the test state, the second switch 241 is only connected to Imeas, responsible for the current output of Imeas, and the first switch 23 is connected to the first fast diode 22. At this time, the temperature corresponding to the measurement time is used as the steady-state junction temperature, and the noise caused by the switching state of 3 to 5us is screened out, so that the test data is more accurate.

[0094] When the intelligent power module 10 is switched to the test state, the voltmeter 21 collects the VF voltage value of the insulated gate bipolar transistor 11, obtains the VF voltage value collected by the voltmeter 21, and then determines the K factor of the insulated gate bipolar transistor 11. The K factor is the relationship coefficient between the chip temperature and the temperature sensitive parameter (voltage VF). The K factor of the insulated gate bipolar transistor 11 can be determined by experimental measurement and data analysis. The steps for determining the K factor are as follows: prepare the test sample, select the IGBT device to be tested, and ensure that its surface is clean so as to accurately measure the temperature response, and install a thermocouple or Infrared thermometer, used to measure temperature response; temperature control, using temperature control equipment (such as constant temperature bath, hot plate, etc.) to place the IGBT under different temperature conditions, and record the chip temperature (Tj) and forward voltage (VF) under each temperature condition; data acquisition, using a data acquisition system to record the chip temperature (Tj) and forward voltage (VF) under each temperature condition to ensure the accuracy and stability of data acquisition; data analysis, based on the measured chip temperature (Tj) and forward voltage (VF) data, draw a relationship curve between Tj and VF, and calculate the K coefficient, that is, the slope between Tj and VF, through linear regression analysis.

[0095] After determining the K coefficient of the IGBT 11 , a first target temperature corresponding to the voltage VF of the IGBT 11 is determined according to the K coefficient, and a thermal resistance of the IGBT is determined according to the first target temperature.

[0096] Traditional thermal resistance testing methods may have low accuracy. Due to factors such as interference from the test environment and errors in the measuring equipment, it is difficult to obtain accurate thermal resistance values. Some thermal resistance testing methods require complex equipment and operating procedures, which increases the cost and time of the test. For example, some methods require the use of expensive thermal imaging equipment or complex mathematical model calculations. Existing thermal resistance testing methods may only be applicable to specific types of devices or specific working conditions, and may not be effectively applicable to new devices or complex application scenarios. Some testing methods cannot monitor the changes in thermal resistance in real time and cannot meet the evaluation requirements of the thermal performance of devices under dynamic working conditions. The embodiments of the present invention can effectively reduce the thermal resistance test noise of modules such as IPM, meet the ever-evolving market needs, and have important practical significance.

[0097] In an embodiment of the present invention, determining the thermal resistance of the insulated gate bipolar transistor according to the first target temperature includes:

[0098] Determining a first power difference generated when the intelligent power module is switched from the working state to the testing state;

[0099] A thermal resistance of the insulated gate bipolar transistor is determined according to the first power difference and the first target temperature.

[0100] Specifically, in the working state, the heating current and the test current are connected at the same time; in the test state, only the test current is connected. Usually, the test current is very small compared to the heating current and can be ignored. The power generated by the test current can also be ignored. However, the test principle requires accurate knowledge of the power difference ΔPHeat. In other words, if the thermal power consumption of the device takes into account PMeas (the power consumption generated by the test current), the method will be more accurate. The larger the heating power difference ΔPH=PHeat-PMeas, the greater the signal-to-noise ratio of the test, and the more accurate the thermal resistance obtained. The thermal resistance of the insulated gate bipolar transistor is determined based on the first power difference and the first target temperature.

[0101] In an embodiment of the present invention, the intelligent power module further includes a second fast diode, and the method further includes:

[0102] obtaining a voltage of the second fast diode measured by the voltmeter after the second fast diode is turned on;

[0103] determining a second coefficient of relationship between voltage and temperature of a second fast diode;

[0104] determining, according to the second relationship coefficient, a second target temperature corresponding to the measured forward voltage drop of the second fast diode;

[0105] According to the second target temperature, a thermal resistance of the second fast diode is determined.

[0106] In an embodiment of the present invention, determining the thermal resistance of the second fast diode according to the second target temperature includes:

[0107] Determining a second power difference generated when the intelligent power module is switched from the working state to the testing state;

[0108] A thermal resistance of the second fast diode is determined according to the second power difference and the second target temperature.

[0109] The method for determining the thermal resistance of the second fast diode refers to the above-mentioned determination of the thermal resistance of the insulated gate bipolar transistor, and the embodiment of the present invention will not be described in detail here.

[0110] Hardware construction requires the selection of appropriate sensors. According to the requirements of thermal resistance testing, high-precision temperature sensors and current / voltage sensors should be selected. These sensors should have good stability, accuracy and fast response capabilities to ensure that the temperature and electrical parameter changes of the device under different working conditions can be accurately measured; design the circuit layout and reasonably plan the layout of the thermal resistance test circuit to ensure the stability and anti-interference ability of signal transmission. A multi-layer circuit board design can be used to separate the wiring of analog signals and digital signals to reduce interference between signals. At the same time, optimize the power supply and grounding design to improve the reliability of the circuit; integrate the control unit, select a suitable microcontroller or digital signal processor as the control unit, which is responsible for collecting sensor data, processing data and calculating thermal resistance values. The control unit should have sufficient computing power and storage capacity to meet the needs of real-time testing and data storage.

[0111] Software programming requires writing the driver of the sensor to ensure that data such as temperature, current and voltage can be accurately read. According to the sensor model and interface type, select the appropriate communication protocol and programming method; develop an efficient data processing algorithm to filter, calibrate and analyze the collected sensor data. Digital filtering technology can be used to remove noise interference and improve the accuracy of the data through calibration algorithms. Then, according to the definition and calculation formula of thermal resistance, the thermal resistance value is calculated using the collected data; design a friendly user interface to facilitate user operation and viewing of test results. A graphical interface can be used to display real-time temperature curves, thermal resistance value changes and other related parameters. At the same time, function buttons such as setting parameters, starting tests and saving data are provided.

[0112] Testing and calibration: After the hardware and software are built, preliminary tests are conducted to verify the basic functions of the circuit. The device to be tested is connected, different working conditions are applied, and the changes in sensor data and the calculated results of thermal resistance values ​​are observed to see if they meet expectations. Based on the results of the preliminary tests, the circuit is calibrated and optimized. Standard devices or reference samples with known thermal resistance values ​​can be used for calibration. The sensor parameters and data processing algorithms can be adjusted to improve the accuracy of the test. Long-term reliability tests are conducted to verify the stability and reliability of the thermal resistance test circuit under different working environments. Harsh environmental conditions such as high temperature, low temperature, and humidity can be simulated to observe changes in circuit performance.

[0113] Practical application: It is applied to the research and development of electronic equipment. In the process of research and development of electronic equipment, thermal resistance test circuits are used to test the thermal performance of power semiconductor devices, integrated circuits, etc. By timely discovering thermal problems, optimizing heat dissipation design, and improving the reliability and performance of equipment; in the production process of electronic products, thermal resistance test circuits are used to perform quality inspections on mass-produced devices. Ensure that the thermal performance of the product meets the standard requirements and improve the quality and consistency of the product; during the operation of the equipment, thermal resistance test circuits are used to perform thermal analysis on faulty devices to help technicians quickly locate the cause of the fault, take effective maintenance measures, and reduce equipment maintenance costs.

[0114] It should be noted that, for the sake of simplicity, the method embodiments are described as a series of action combinations, but those skilled in the art should be aware that the embodiments of the present invention are not limited by the order of the actions described, because according to the embodiments of the present invention, certain steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification are all preferred embodiments, and the actions involved are not necessarily required by the embodiments of the present invention.

[0115] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0116] It will be appreciated by those skilled in the art that the embodiments of the present invention may be provided as methods, devices, or computer program products. Therefore, the embodiments of the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the embodiments of the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0117] The embodiments of the present invention are described with reference to the flowcharts and / or block diagrams of the methods, terminal devices (systems), and computer program products according to the embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of the processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing terminal device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing terminal device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0118] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing terminal device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce a manufactured product including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0119] These computer program instructions can also be loaded onto a computer or other programmable data processing terminal device so that a series of operating steps are executed on the computer or other programmable terminal device to produce a computer-implemented process, thereby providing instructions for executing on the computer or other programmable terminal device to implement the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0120] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present invention.

[0121] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or terminal device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or terminal device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or terminal device including the elements.

[0122] The above is a detailed introduction to a test circuit and method for an intelligent power module provided by the present invention. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for a person skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A test circuit for an intelligent power module, characterized in that: The intelligent power module includes an insulated gate bipolar transistor, and the test circuit includes a voltmeter, a first fast diode, a first switch and a current input circuit; The voltmeter, the first fast diode and the first switch are connected in series; The insulated gate bipolar transistor is connected in parallel with a series circuit of the voltmeter, the first fast diode and the first switch; The current input circuit is connected to a series circuit of the voltmeter, the first fast diode and the first switch; When the insulated gate bipolar transistor is configured to be turned on, the first switch is configured to be turned off, and the intelligent power module is in an operating state, the current input circuit is used to provide a heating current and a test current in a first current flow direction; When the insulated gate bipolar transistor is configured to be turned on, the first switch is configured to be closed, and the intelligent power module is switched from the working state to the test state, the current input circuit is used to provide a test current in a first current flow direction so as to delay the turn-on of the first fast diode; and the voltmeter is used to measure the forward voltage drop of the insulated gate bipolar transistor after the first fast diode is turned on.

2. The test circuit according to claim 1, characterized in that: The current input circuit comprises a second switch; a first end of the second switch is connected to the first switch, a second end is connected to the first current source, and a third end is connected to the second current source; the first current source is used to provide a heating current, and the second current source is used to provide a test current; When the intelligent power module is in working state, the second end and the third end of the second switch are closed; when the intelligent power module is switched from the working state to the test state, the second end of the second switch is disconnected and the third end of the second switch is closed.

3. The test circuit according to claim 1, characterized in that: The first fast diode is a unidirectional conducting diode; the conducting direction of the first fast diode is the same as the first current flow direction of the test current provided by the current input circuit.

4. The test circuit according to claim 1, characterized in that: The intelligent power module also includes a second fast diode; the second fast diode is arranged between the collector and the emitter of the insulated gate bipolar transistor; and the conduction direction of the insulated gate bipolar transistor is opposite to that of the insulated gate bipolar transistor.

5. The test circuit according to claim 4, characterized in that: When the insulated gate bipolar transistor is configured to be turned off so that the second fast diode is turned on, the first switch is configured to be turned off, and the intelligent power module is in a working state, the current input circuit is used to provide a heating current and a test current in a second current flow direction; the first current flow direction is opposite to the second current flow direction; When the insulated gate bipolar transistor is configured to be cut off, the first switch is configured to be closed, and the intelligent power module is switched from the working state to the test state, the current input circuit is used to provide a test current in the second current flow direction to cut off the first fast diode and turn on the second fast diode; the voltmeter is used to measure the voltage of the second fast diode after the second fast diode is turned on.

6. The test circuit according to claim 4, characterized in that: When the insulated gate bipolar transistor is configured to be turned on so that the second fast diode is turned off, the first switch is configured to be turned off, and the intelligent power module is in a working state, the current input circuit is used to provide a heating current and a test current in a first current flow direction; When the insulated gate bipolar transistor is configured to be turned on so that the second fast diode is cut off, the first switch is configured to be closed, and when the intelligent power module is switched from the working state to the test state, the current input circuit is used to provide a test current in a first current flow direction so that the first fast diode is delayed in turning on; and the voltmeter is used to measure the forward voltage drop of the insulated gate bipolar transistor after the first fast diode is turned on.

7. A method for testing an intelligent power module, characterized in that: Relating to the test circuit as described in claims 1 to 6 above, the method comprises: Obtaining a forward voltage drop of the insulated gate bipolar transistor measured by the voltmeter after the first fast diode is turned on; Determining a first relationship coefficient between a forward voltage drop and temperature of an insulated gate bipolar transistor; determining a first target temperature corresponding to the measured forward voltage drop of the insulated gate bipolar transistor according to the first relationship coefficient; A thermal resistance of the insulated gate bipolar transistor is determined according to the first target temperature.

8. The testing method according to claim 7, characterized in that: Determining the thermal resistance of the insulated gate bipolar transistor according to the first target temperature includes: Determining a first power difference generated when the intelligent power module is switched from the working state to the testing state; A thermal resistance of the insulated gate bipolar transistor is determined according to the first power difference and the first target temperature.

9. The testing method according to claim 7, characterized in that: The intelligent power module further includes a second fast diode, and the method further includes: obtaining a voltage of the second fast diode measured by the voltmeter after the second fast diode is turned on; determining a second coefficient of relationship between voltage and temperature of a second fast diode; determining, according to the second relationship coefficient, a second target temperature corresponding to the measured forward voltage drop of the second fast diode; According to the second target temperature, a thermal resistance of the second fast diode is determined.

10. The testing method according to claim 9, characterized in that: Determining the thermal resistance of the second fast diode according to the second target temperature includes: Determining a second power difference generated when the intelligent power module is switched from the working state to the testing state; A thermal resistance of the second fast diode is determined according to the second power difference and the second target temperature.

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