CN109164370B - Thermal impedance measurement system and method of power semiconductor device - Google Patents

Abstract

The invention provides a thermal impedance measuring system and method of a power semiconductor device, wherein the system comprises: the device comprises a direct current power supply module, a tested module, a driving module, a measuring module and a master control module; wherein: the direct current power supply module is used for supplying electric energy to the module to be tested; the tested module comprises at least one tested unit; the driving module is used for amplifying the power of the switch state signal output by the master control module so as to drive a power device in the tested unit; the measuring module is used for detecting the electrical state and the temperature state of the module to be measured; and the master control module is used for analyzing and processing the result measured by the measuring module to obtain the thermal impedance characteristic of the power semiconductor device in the measured unit. The invention can realize more accurate thermal impedance characteristic measurement of a plurality of power semiconductor devices, and the cost of the test system is greatly reduced.

Description

Thermal impedance measurement system and method of power semiconductor device

technical field

The present invention relates to the technical field of power electronics, and in particular, to a thermal impedance measurement system and method of a power semiconductor device.

Background technique

Power semiconductor devices are important components in power electronic converters, and abnormal operation of power semiconductor devices is the main cause of failure of the converter. In order to improve the reliability and economy of the converter, it is necessary to accurately predict and evaluate the thermal behavior and working efficiency of the power semiconductor devices. Before this, the thermal impedance characteristics of the power semiconductor devices must be accurately obtained.

According to the definition formula of thermal impedance, to obtain the thermal impedance characteristics of power semiconductor devices, it is necessary to obtain the dynamic temperature change of the device under test and the power loss of the device. The existing technology usually uses a current source of constant magnitude and direction to heat the power semiconductor device that is continuously conducting. When it reaches a thermally stable state, an additional switch is used to cut off the heating current, and the temperature of the device under test at multiple points during the cooling process is recorded. Variety. Since the power loss during the heating process of the device under test only includes the conduction loss, it can be obtained by the product of the conduction voltage on the device and the heating current before being cut off.

However, power semiconductor devices are usually in a high-speed switching state in practical applications, and their power loss includes not only conduction loss, but also large switching loss, which is the main heat source of the device. When using the traditional thermal impedance measurement method, in order to achieve a temperature range similar to the actual operation, it is necessary to make the device under test work in a linear amplification state, or apply a heating current much larger than the actual operating current of the device. This also makes the thermal impedance test method of traditional power semiconductor devices, which has significant problems such as high test system cost, slow heating current change speed, single heating current direction, fixed device under test, and device working state inconsistent with practical applications.

SUMMARY OF THE INVENTION

In view of the defects in the prior art, the purpose of the present invention is to provide a thermal impedance measurement system and method of a power semiconductor device.

In a first aspect, an embodiment of the present invention provides a thermal impedance measurement system for a power semiconductor device, including: a DC power supply module, a measured module, a driving module, a measurement module, and a general control module; wherein:

The DC power supply module is configured to provide electrical energy to the module under test according to a given reference voltage provided by the general control module;

The module under test includes: at least one unit under test, the unit under test is used to simulate the working state of the power semiconductor device; the unit under test includes: a measurement circuit composed of the power semiconductor device, and the measurement circuit corresponds to the load module;

The driving module is used for power amplifying the switching state signal output by the general control module to obtain a corresponding driving signal, and controlling the switching state of the power semiconductor device in the unit under test through the driving signal;

The measurement module is configured to detect the electrical state and temperature state of the power semiconductor device in the measurement circuit and the load module corresponding to the measurement circuit according to the measurement signal provided by the general control module;

The general control module is configured to provide a given reference voltage to the DC power supply module, and to analyze and process the results measured by the measurement module to obtain thermal impedance characteristics of the power semiconductor device in the unit under test.

Optionally, the measurement circuit includes: a full-bridge circuit composed of power semiconductor devices, or an H-bridge circuit.

Optionally, the measurement circuit further includes: a heat sink, where the heat sink is used to dissipate heat generated by the power semiconductor device.

Optionally, the measurement module includes: a temperature measurement sub-module, a voltage measurement sub-module, and a current measurement sub-module; wherein:

The temperature measurement sub-module is used to obtain the temperature parameters of the measurement circuit, and the temperature parameters include: any one or more of the junction temperature of the power semiconductor device, the shell temperature of the power semiconductor device, the temperature of the heat sink, and the ambient temperature a temperature value;

The voltage measurement sub-module is used to obtain the voltage value of the power semiconductor device in the measurement circuit and the corresponding load module in the measurement circuit;

The current measurement sub-module is used to obtain the current value of the power semiconductor device in the measurement circuit and the corresponding load module in the measurement circuit.

Optionally, the temperature measurement sub-module adopts a temperature sensor, or a temperature-sensitive electrical parameter measurement sensor;

The load module corresponding to the measurement circuit includes any of the following forms:

pure inductive circuit;

A hybrid electrical impedance network composed of inductors, capacitors, resistors, and transformers.

Optionally, the power semiconductor device includes any of the following types:

Semiconductor chips based on silicon, silicon carbide, and gallium nitride;

Power semiconductor devices made with module, crimp, and discrete packaging technologies.

In a second aspect, an embodiment of the present invention provides a thermal impedance measurement method for a power semiconductor device, which is applied to the thermal impedance measurement system for a power semiconductor device according to any one of the first aspects. The method includes:

Control the switching state of the power semiconductor device in the unit under test according to the driving signal, so as to form a heating current in the unit under test;

After the power semiconductor device reaches a thermally stable state, the switching state of the power semiconductor device in the unit under test is controlled by the drive signal, and the heating current in the unit under test is changed;

Acquire the power loss of the power semiconductor device in the unit under test, and measure and record the temperature change value of the power semiconductor device;

According to the power loss and temperature change value of the power semiconductor device, the thermal impedance parameter of the power semiconductor device is obtained by analysis.

Optionally, the form of the heating current includes any of the following:

Unidirectional pulse current flowing through power semiconductor devices;

Continuous direct current, or alternating current, flowing through a power semiconductor device.

Optionally, the power loss of the power semiconductor device includes switching loss and conduction loss.

Compared with the prior art, the present invention has the following beneficial effects:

1. The thermal impedance measurement system of the power semiconductor device provided by the present invention can freely and quickly adjust the size and direction of the heating current of the device under test, so as to realize the cyclic measurement of single or multiple devices under test, and increase the reliability and reliability of the measurement data. Universality.

2. In the thermal impedance measurement system for power semiconductor devices provided by the present invention, the test circuit structure is similar to the circuit topology commonly used in power semiconductor devices, and the device under test works in the switching state in practical applications, so the obtained test data is more accurate. Close to the characteristics of the device under test under actual operating conditions.

3. The thermal impedance measurement method of a power semiconductor device provided by the present invention takes into account the switching loss of the power semiconductor device under actual operating conditions, so that the heating current required to reach the same test temperature is smaller, and the heating current depends on the working state of the device under test. Free adjustment, thus avoiding additional switches, the power supply system can use a smaller power voltage source, thus greatly reducing the cost of the test system.

4. The thermal impedance measurement method of the power semiconductor device provided by the present invention can realize the rapid decrease of the heating current, so that the power loss of the device under test is closer to the ideal step signal, and the obtained thermal impedance data is more accurate.

Description of drawings

Other features, objects and advantages of the present invention will become more apparent by reading the detailed description of non-limiting embodiments with reference to the following drawings:

1 is a schematic structural diagram of a power semiconductor device thermal impedance measurement system provided by the present invention;

Fig. 2 is the structural representation of the module under test in the present invention;

3 is a schematic structural diagram of Embodiment 1 of the thermal impedance measurement system for a power semiconductor device provided by the present invention;

4 is a flowchart of a method for measuring thermal impedance of a power semiconductor device provided by the present invention;

5 is a schematic diagram of a load current waveform of Embodiment 1 of the thermal impedance measurement method provided by the present invention;

6 is a schematic diagram of waveforms of testing a group of power semiconductor devices under test in Embodiment 1 of the thermal impedance measurement method provided by the present invention.

In the picture:

1-DC power supply module;

2- the module under test;

3- drive module;

4- total control module;

5- Measurement module.

Detailed ways

The present invention will be described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that, for those skilled in the art, several changes and improvements can be made without departing from the inventive concept. These all belong to the protection scope of the present invention.

FIG. 1 is a schematic structural diagram of a thermal impedance measurement system for a power semiconductor device provided by the present invention. As shown in FIG. 1, the system may include: a DC power supply module 1, a measured module 2 (including n measured units and n measured radiator), drive module 3, measurement module 5, total control module 4. Wherein, the number of DC output port groups of the DC power supply module 1 is the same as the number of the tested units (as shown in FIG. 1 including n tested units, n is an integer greater than or equal to 1), the output ports of the DC power supply module 1 Correspondingly connected to the DC bus of the unit under test. The DC power supply module 1 can change the DC voltage at the output terminal according to the DC voltage reference given value of the general control module 4 . The driving module 3 receives the switch state signal output by the general control module 4 and amplifies the power of the signal to drive the power semiconductor device in the unit under test. The measurement module 5 is used to detect the electrical and temperature states of the power semiconductor device and the load module in the unit under test; the overall control module 4 determines and evaluates the electrical and temperature information detected by the measurement module 5. operation, and provide the switch state signal of the drive module 3 ; or provide the reference given value of the DC power supply module 1 ; or provide the measurement signal of the measurement module 5 .

FIG. 2 is a schematic structural diagram of a tested module in the present invention. As shown in FIG. 2 , the tested module includes a tested unit and an optional tested radiator. The unit under test includes an H-bridge or full-bridge circuit composed of two bridge arms (identified as ARM1 and ARM2 in FIG. 2 ) and a corresponding load module 7; wherein the bridge arms are any topology formed by power semiconductor devices. The number of the load modules is the same as the number of the units under test, and the two ports of each load module are respectively connected to the midpoints of the two bridge arms in each unit under test. In Figure 2, each bridge arm includes two power semiconductor device modules under test (identified as DUT1_H, DUT1_L and DUT2_H, DUT2_L in Figure 2) connected in series in the same direction, and a heat sink under test corresponding to the power semiconductor device under test (in Figure 2). Marked as HS1_H, HS1_L and HS2_H, HS2_L), the power semiconductor devices in the module under test 2 include: insulated gate bipolar transistors (IGBTs) and diodes (Diodes) connected in reverse parallel with the IGBTs.

3 is a schematic structural diagram of Embodiment 1 of the thermal impedance measurement system for power semiconductor devices provided by the present invention; including a unit under test, a drive module 3, a general control module 4 and a measurement module 5; wherein the unit under test includes a H-bridge test circuit and a pure inductive load module L, the H-bridge test circuit includes four tested power semiconductor device modules DUT1_H (including T1, D1), DUT1_L (including T2, D2), DUT2_H (including T3, D3), DUT2_L (including T4, D4); the measurement module 5 measures the electrical/temperature states of the power semiconductor devices DUT1_H, DUT1_L, DUT2_H, DUT2_L, the inductive load L and the corresponding heat sink respectively through five probes S1, S2, S3, S4, and SL, wherein The probe includes one or more of a voltage probe, a current probe, and a temperature measurement probe; the measurement module also measures the junction temperature of the four tested power semiconductor device modules through the four junction temperature measurement modules ST1, ST2, ST3, and ST4 . The four junction temperature measurement modules use the on-voltage drop of the power semiconductor device under test as a temperature-sensitive parameter to estimate the junction temperature of the device.

Further, on the basis of the power semiconductor device thermal impedance measurement platform, the present invention proposes a corresponding power semiconductor thermal impedance measurement method, and FIG. 4 is a flowchart of the power semiconductor device thermal impedance measurement method provided by the present invention; The cyclic test method for thermal impedance of all power semiconductor devices in given heating current and heat dissipation conditions is as follows:

S1: Set the device under test, and execute step S2;

S2: According to the set device under test, set the size and direction of the heating current, use it as the current target value of the load module in the module under test, and execute step S3;

S3: By controlling the switch of the device in the test unit, a current is generated in the load module. When the electrical steady state is reached, the current flowing through the device under test is a continuous current or a unidirectional pulse current with a fixed duty ratio, and step S4 is performed;

S4: record the temperature of the device under test, if the device under test has reached a thermally stable state, execute step S5, and if the device under test has not reached a thermally stable state, return to step S3;

S5: quickly cut off the heating current by controlling the switch of the device in the test unit, and execute step S6;

S6: record the temperature change of the device under test during the cooling process, and execute step S7;

S7: Compare the temperature of the test device with the ambient temperature. If the junction temperature of the device under test has reached the ambient temperature, execute step S8; if the junction temperature of the device under test is still higher than the ambient temperature, return to step S3;

S8: if all the devices under test have completed the thermal impedance measurement, go to step S9; if there is still a device under test in the module under test that has not completed the thermal impedance measurement, go back to step S1;

S9: The test is over.

FIG. 5 is a schematic diagram of the load current waveform of Embodiment 1 of the thermal impedance measurement method provided by the present invention, and the sequence of cyclic thermal impedance measurement of the four power semiconductor device modules (a total of eight devices under test) in FIG. 3 is given, The current reference direction is from ARM1 to ARM2 in FIG. 2 . One thermal impedance measurement cycle (T marked in Figure 5) includes four heating processes (P1, P3, P5, P7 marked in Figure 5) and corresponding cooling processes (P2, P4, P6, P8 marked in Figure 5) ). Different load current directions can heat different devices under test. When the load current is positive, T1, D2, D3, and T4 can be heated. When the load current is negative, D1, T2, T3, and D4 can be heated. to heat. The length of the cooling process is determined according to the test conditions and the test target. In this embodiment, the conduction voltage drop of the device is used to measure the junction temperature. In order to avoid the temperature rise caused by the short circuit of the measurement unit and the change of the load current during the cooling process, it cannot be turned on at the same time. Modules on the same bridge arm or diagonal bridge arm can perform temperature measurement, that is, temperature measurement can only be performed on the following two combined devices at the same time, DUT1_H and DUT2_H, DUT1_L and DUT2_L. FIG. 6 shows a schematic diagram of waveforms when testing a group of tested power semiconductor devices (marked as P1 and P2 in FIG. 5 ) according to Embodiment 1 of the thermal impedance measurement method provided by the present invention, including load current i _L , device junction temperature T _j , test current i _M and driving voltage waveform v _GE of the power semiconductor device. In the P1 and P2 stages, the thermal impedance measurement is performed on T1 and D3 at the same time. In the P1 stage, the load current is controlled to a constant DC current with negligible ripple through the fast switching of the four power semiconductor devices in the measurement unit. device is heated. When the device under test reaches a thermally stable state, by changing the switching state, the load current rapidly drops to zero and enters the P2 stage. In the P2 stage, the measurement current is injected into T1 and D3 through the junction temperature measurement modules ST1 and ST3 to keep the device under test on. The measurement current is much smaller than the heating current, and the heat generated by the measurement current is negligible.

It should be noted that the steps in the method for testing the thermal impedance characteristics of the power semiconductor device provided by the present invention can be implemented by using the corresponding modules, devices, units, etc. in the test platform for the loss characteristics of the power semiconductor device. A skilled person can refer to the technical solution of the system to implement the step flow of the method, that is, the embodiments in the system can be understood as preferred examples for implementing the method, which will not be repeated here.

The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the above-mentioned specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essential content of the present invention. The embodiments of the present application and features in the embodiments may be arbitrarily combined with each other without conflict.

Claims (6)

1. A thermal impedance measurement system for a power semiconductor device, comprising: the device comprises a direct current power supply module, a tested module, a driving module, a measuring module and a master control module; wherein:

the direct current power supply module is used for providing electric energy for the tested module according to the given reference voltage provided by the master control module;

the module under test comprises: the device comprises at least one tested unit, a power semiconductor device and a control unit, wherein the tested unit is used for simulating the working state of the power semiconductor device, so that the current flowing through the power semiconductor device is a unidirectional pulse current with a fixed duty ratio when the measuring system reaches a heating electric stable state; the unit under test includes: the power semiconductor device comprises a measuring circuit consisting of power semiconductor devices and a load module corresponding to the measuring circuit;

the driving module is used for carrying out power amplification on the switching state signal output by the master control module to obtain a corresponding driving signal and controlling the switching state of a power semiconductor device in the tested unit through the driving signal;

the measuring module is used for detecting the electrical states and temperature states of the power semiconductor devices in the measuring circuit and the load modules corresponding to the measuring circuit according to the measuring signals provided by the master control module;

the master control module is used for providing a given reference voltage for the direct current power supply module and analyzing and processing the result measured by the measuring module to obtain the thermal impedance characteristic of the power semiconductor device in the unit to be measured;

the measurement circuit further comprises: a heat sink for dissipating heat generated by the power semiconductor device;

the measurement module includes: the temperature measuring submodule, the voltage measuring submodule and the current measuring submodule are connected; wherein:

the temperature measurement submodule is configured to obtain a temperature parameter of the measurement circuit, where the temperature parameter includes: any one or more of junction temperature of the power semiconductor device, shell temperature of the power semiconductor device, temperature of a radiator and ambient temperature;

the voltage measurement submodule is used for acquiring voltage values of a power semiconductor device in a measurement circuit and a corresponding load module in the measurement circuit;

the current measuring submodule is used for obtaining current values of the power semiconductor device in the measuring circuit and the corresponding load module in the measuring circuit.

2. The system of claim 1, wherein the measurement circuit comprises: a full bridge circuit composed of power semiconductor devices, or an H-bridge circuit.

3. The system for measuring the thermal impedance of the power semiconductor device according to claim 1, wherein the temperature measuring submodule adopts a temperature sensor or a temperature-sensitive electrical parameter measuring sensor;

the corresponding load module in the measuring circuit comprises any one of the following forms:

a pure inductive circuit;

the mixed type electrical impedance network consists of an inductor, a capacitor, a resistor and a transformer.

4. Thermal impedance measurement system of a power semiconductor device according to any of claims 1-3, characterized in that the power semiconductor device comprises any of the following types:

semiconductor chips based on silicon, silicon carbide, gallium nitride;

the power semiconductor device is manufactured by adopting module, compression joint and discrete packaging technologies.

5. A thermal impedance measurement method of a power semiconductor device, which is applied to a thermal impedance measurement system of a power semiconductor device according to any one of claims 1 to 4, the method comprising:

controlling the switching state of a power semiconductor device in a unit under test according to a driving signal so as to form a heating current in the unit under test;

after the power semiconductor device reaches a thermal stable state, controlling the switching state of the power semiconductor device in the tested unit through the driving signal, and changing the heating current in the tested unit;

acquiring the power loss of a power semiconductor device in the unit to be tested, and measuring and recording the temperature change value of the power semiconductor device;

analyzing to obtain a thermal impedance parameter of the power semiconductor device according to the power loss and the temperature change value of the power semiconductor device;

the form of the heating current includes any one of:

a unidirectional pulse current flowing through the power semiconductor device;

a continuous direct current, or an alternating current, flowing through the power semiconductor device.

6. The method of claim 5, wherein the power loss of the power semiconductor device comprises: switching losses and conduction losses.

Images