A power circulation main circuit for GaN power devices

Abstract

A power circulation main circuit for a GaN power device, comprising a plurality of lines and a voltage source V load The modules to be tested are connected in parallel. The modules to be tested include a microprocessor, an isolation circuit, a D / A conversion circuit, an inverter, a negative feedback constant voltage source driving module, and a GaN device. The microprocessor is connected to the isolation circuit, and the isolation circuit is respectively connected to the D / A conversion circuit and the inverter, and the D / A conversion circuit and the inverter are all connected to the negative feedback constant voltage source driving module, and the negative feedback constant voltage source driving module is connected to the GaN device. The GaN device is connected to the measurement circuit, and the measurement circuit includes a thermocouple and a current sensor, and the thermocouple and the current sensor are all connected to the microprocessor. The main circuit of the present invention adopts a parallel aging control strategy, that is, multiple groups of modules to be tested are aged at the same time. Compared with the traditional power cycle circuit, this circuit has the characteristics of high aging efficiency, high power utilization, simple control method, and the aging of each GaN device to be tested is decoupled from each other and easy to expand.

Description

Technical Field

[0001] The invention relates to the technical field of power semiconductor device measurement, and in particular to a power circulation main circuit for a GaN power device. Background Art

[0002] With the development of semiconductor technology and power electronics technology, the application fields of semiconductor devices have expanded to important fields such as military industry, aerospace, and new energy power generation. Wide bandgap semiconductor devices represented by gallium nitride (GaN) and silicon carbide (SiC) have also been widely used with the general trend of high frequency and high power density of power electronics. Initially, GaN devices were only used in military fields such as radar and laser. Due to the advancement of manufacturing technology, their costs have gradually decreased, which has gradually expanded the application scope of GaN devices to the civilian field. However, GaN devices are still in the early stages of development, their failure mechanisms are still under research, and their reliability still needs to be improved. The aging process of GaN devices can be accelerated through accelerated aging tests, so as to study the characteristics of their failures, which is not only of great significance for understanding the aging mode of GaN devices, but also of great significance for improving the reliability of GaN devices.

[0003] At present, power cycle tests are commonly used to accelerate the aging of semiconductor devices and test their reliability. Power cycle tests simulate the thermal, electrical, mechanical stress or the coupled stress of the three under the actual working conditions of the device by applying power to the device under test, generating heat loss and causing the device temperature to fluctuate periodically, thereby simulating and accelerating the aging process of the device under actual working conditions, and then exposing the possible failure of the device during long-term operation in advance, so as to conduct reliability assessment, failure mechanism research and structural optimization design of the device.

[0004] Existing power circulation circuits are mainly divided into two types: series type and parallel type. The series power circulation circuit connects the device under test and the current source in series, and uses a switch to turn the device under test on and off. The series power circulation circuit can age multiple groups of devices under test connected in series at the same time, and has the characteristics of high efficiency. However, the series power circulation circuit cannot use the cooling time section, and its time utilization rate is low; in addition, the series power circulation circuit realizes power circulation by turning on and off the power current source. Such frequent turning on and off of the current source will reduce its life, thereby reducing the reliability of the power circulation circuit. The parallel power circulation circuit is also a commonly used power circulation circuit. This type of circuit connects multiple groups of devices under test with the current source in parallel, and each group of devices under test is turned on and off by a switch. The time utilization rate of the parallel power circulation circuit is often improved by staggered conduction, and multiple devices under test can be connected in series on a branch to increase the aging efficiency. In addition, a bypass can be added to improve the reliability of the current source. However, staggered conduction will make the control method complicated, and adding a bypass will increase the cost. Summary of the invention

[0005] In view of the above-mentioned deficiencies of the existing power circulation circuits, the present invention provides a power circulation main circuit for GaN power devices, which can achieve efficient aging of multiple groups of GaN power devices with a simple control method, and the power circulation main circuit has a high time utilization rate.

[0006] The technical solution adopted by the present invention is:

[0007] A power circulation main circuit for a GaN power device, comprising: a plurality of lines connected to a voltage source V load Modules under test connected in parallel;

[0008] The module to be tested includes a microprocessor, an isolation circuit, a D / A conversion circuit, an inverter, a negative feedback constant voltage source drive module, and a GaN device;

[0009] The microprocessor is connected to the isolation circuit, the isolation circuit is respectively connected to the D / A conversion circuit and the inverter, the D / A conversion circuit and the inverter are both connected to the negative feedback constant voltage source drive module, and the negative feedback constant voltage source drive module is connected to the GaN device;

[0010] The GaN device is connected to a measuring circuit, which includes a thermocouple and a current sensor, and both the thermocouple and the current sensor are connected to a microprocessor.

[0011] The voltage source V load , used to provide the drain-source voltage V for the GaN device DS , so that the GaN device works in the active area. The microprocessor output signal enters port 1 of the negative feedback constant voltage source drive module through the isolation circuit and the D / A conversion circuit, and the microprocessor output signal enters port 2 of the negative feedback constant voltage source drive module through the isolation circuit and the inverter. By changing the output of the microprocessor, the negative feedback constant voltage source drive module can be adjusted to achieve the gate-source voltage V of the GaN device under test. GS The drain-source current I flowing through the GaN device under test can be adjusted by adjusting DS .

[0012] The thermocouple is used to measure the temperature of the GaN device;

[0013] The current sensor is used to measure the drain-source current I of the GaN device. DS .

[0014] The negative feedback constant voltage source driving module is composed of a subtractor cascaded with an integration circuit. The output terminal V out The same-direction input terminal of the subtractor is led back to form negative feedback; the voltage at port 1 of the negative feedback constant voltage source driving module is inverted with the voltage at port 2.

[0015] The present invention provides a power circulation main circuit for GaN power devices, and the technical effects are as follows:

[0016] 1) The present invention is used to perform power cycle testing on power semiconductor devices. The main circuit uses a voltage source connected in parallel with multiple modules to be tested, wherein the voltage source provides a specific drain-source V for the GaN device to be tested. DS , so that the GaN device under test works in the active region. The gate-source V GS The microprocessor can change it by adjusting the negative feedback constant voltage source drive, so as to adjust the aging power of the GaN device and realize the control of the aging process.

[0017] Negative feedback constant voltage source drive can also be used to monitor the junction temperature when GaN devices are aging and heating up. Thanks to the parallel structure, the control method of the main circuit is simple, and multiple groups of modules to be tested can be aged at the same time. Each group of modules to be tested is decoupled from each other and easy to expand. The main circuit has the characteristics of high time utilization and high aging efficiency.

[0018] 2). The main circuit of the present invention can implement multiple groups of aging strategies, such as: quasi-junction temperature fluctuation aging strategy, constant shell temperature fluctuation aging strategy and constant on-time and off-time aging strategy, to meet different test requirements. The junction temperature measurement strategy of the present invention under different aging strategies is as follows: if the main circuit performs a power cycle with quasi-junction temperature fluctuation, the drain-source I of the GaN device under test is detected by the current sensor in the measurement circuit when the GaN device under test is on and aged. DS To detect the junction temperature, and when the GaN device under test is disconnected for cooling, the case temperature of the GaN device under test is detected by the thermocouple in the measurement circuit to reflect the junction temperature; if the main circuit is power cycled under the aging strategy of constant case temperature fluctuation, it is only necessary to measure the case temperature of the GaN device under test through the thermocouple of the measurement circuit; if the main circuit is power cycled under the aging strategy of constant on-off time, the method of measuring the junction temperature is similar to the measurement method of the device under test under the quasi-junction temperature fluctuation aging strategy.

[0019] 3) Compared with the traditional power circulation circuit, the main circuit of the present invention does not need to configure additional switches, and only needs to control the negative feedback voltage source drive by the microprocessor according to the preset timing to adjust the V of the GaN device under test. GS , thereby realizing the disconnection of the GaN device under test. This not only greatly simplifies the control of the main circuit, but also saves costs; it is also conducive to the maintenance of the main circuit.

[0020] 4) The main circuit of the present invention adopts a parallel aging control strategy, that is, aging multiple groups of modules under test at the same time. Compared with the traditional power cycle circuit, this circuit has the characteristics of high aging efficiency, high power utilization, simple control method, and mutual decoupling and easy expansion of the aging of each GaN device under test. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is the main circuit diagram of the present invention.

[0022] Figure 2 It is a schematic diagram of the module to be tested in the main circuit of the present invention.

[0023] Figure 3 It is a schematic diagram of the negative feedback constant voltage source driving module in the module under test.

[0024] Figure 4 This is a graph showing the relationship between the volt-ampere characteristics and junction temperature of a GaN device in the data sheet.

[0025] FIG5(1) is a timing diagram of the main circuit of the present invention operating under the quasi-junction temperature fluctuation aging control strategy. Figure 1 ;

[0026] FIG5(2) is a timing diagram of the main circuit of the present invention operating under the quasi-junction temperature fluctuation aging control strategy. Figure 2 ;

[0027] FIG5(3) is a timing diagram of the main circuit of the present invention operating under the quasi-junction temperature fluctuation aging control strategy. Figure 3 .

[0028] FIG6 (1) is a timing diagram of the main circuit of the present invention being turned on and working under a constant shell temperature fluctuation aging strategy;

[0029] FIG6 (2) is a timing diagram of the shutdown operation of the main circuit of the present invention under the constant shell temperature fluctuation aging strategy.

[0030] FIG. 7 (1) is a timing diagram of the main circuit of the present invention operating under the on-time aging strategy. Figure 1 .

[0031] FIG. 7 (2) is a timing diagram of the main circuit of the present invention operating under the off-time aging strategy. Figure 2 . DETAILED DESCRIPTION

[0032] like Figure 1 As shown, a power cycle main circuit for GaN power devices includes: a plurality of lines connected to a voltage source V load The modules to be tested are connected in parallel. Among them, the voltage source V load Provide an appropriate drain-source voltage V for the GaN device under test DS , so that the GaN device under test works in the active region.

[0033] like Figure 2As shown, the module to be tested includes a microprocessor, an isolation circuit, a D / A conversion circuit, an inverter, a negative feedback constant voltage source drive module, a GaN device DUT, and a heat sink a. The heat sink a is used to accelerate the cooling of the device, and can be composed of an adjustable speed fan and a heat sink. The PWM function of the microprocessor is used to drive the motor drive module TB6612 in the fan, thereby controlling the cooling speed of the device.

[0034] The microprocessor is connected to the isolation circuit, the isolation circuit is respectively connected to the D / A conversion circuit and the inverter, the D / A conversion circuit and the inverter are all connected to the negative feedback constant voltage source drive module, the negative feedback constant voltage source drive module is connected to the GaN device, and the GaN device is connected to the measurement circuit, the measurement circuit includes a thermocouple b and a current sensor c, and the thermocouple b and the current sensor c are all connected to the microprocessor. The microprocessor can control the negative feedback constant voltage source to change the gate-source voltage V of the GaN device under test. GS , and then a parallel aging strategy can be used to achieve simultaneous aging of multiple groups of modules under test. Thermocouple b and current sensor c measure the junction temperature or shell temperature, as well as the current.

[0035] Taking GaN System's GS61008P power chip as an example, according to its data sheet "GS61008PBottom-side cooled 100V E-mode GaN transistor", GaN power devices have a certain gate-source voltage V GS Under the volt-ampere characteristic, the drain-source voltage V DS and the drain-source current I DS The relationship between I and junction temperature is a negative temperature characteristic, that is, the higher the junction temperature, the DS The smaller the I is, the smaller the GaN device under test can be used. DS To reflect the junction temperature.

[0036] The microprocessor output signal enters port 1 of the negative feedback constant voltage source drive module through the isolation circuit and D / A conversion circuit. The microprocessor output signal enters port 2 of the negative feedback constant voltage source drive module through the isolation circuit and inverter. By changing the output of the microprocessor, the negative feedback constant voltage source drive module can be adjusted to achieve the gate-source voltage V of the GaN device under test. GS The drain-source current I flowing through the GaN device under test can be adjusted by adjusting DS Based on the above functional description, a hardware selection for implementation is given:

[0037] The microprocessor can be ST's STM32 series or TI's C2000 series;

[0038] The isolation circuit can use APCL series optical coupling isolators;

[0039] The D / A conversion circuit can use Microchip's MCP4725;

[0040] The inverter can be TI's 74HC14D.

[0041] Thermocouple b can be the MAX31855K ​​thermocouple produced by Maxim Corporation.

[0042] The current sensor c can be ACS758KCB-200B-PFF-T produced by ALLEGRO.

[0043] like Figure 3 As shown, the negative feedback constant voltage source drive module consists of a subtractor cascaded with an integration circuit. The integrator outputs V out Lead back to the same-direction input terminal of the subtractor to form negative feedback, Figure 3 Medium V in is connected to port 1, and the control end of switch S1 is connected to port 2. Figure 2 As we know, the voltage at port 1 is in opposite phase to the voltage at port 2, that is, V in The control signal of S1 is inverted. So when the microprocessor outputs a low level, the voltage of port 1, i.e., V in =0V, so V out =0V, and the input signal of port 2 is positive, S1 is turned on, and the capacitor C1 in the integrator is discharged through R4; when the microprocessor outputs a high level, the voltage of port 1, i.e., V in >0V, so V out >0V, while the input signal of port 2 is zero, S1 is turned off. The discharge circuit of capacitor C1 ensures that when the microprocessor outputs a high level, capacitor C1 has no initial energy storage, which makes the initial energy storage not affect V out .

[0044] Figure 4 The data sheet "GS61008P Bottom-side cooled 100V E-mode GaN transistor" shows the relationship between the volt-ampere characteristics of GaN devices and the junction temperature. GS =6V. It can be seen from the figure that as the GaN device's V DS Increase, I DS Increase first, wait for I DS After reaching the active region I DS No longer follow V DS In addition, as the junction temperature of the GaN device increases, at a certain V DS Next I DS Getting smaller and smaller, that is, I DSIt has a negative temperature characteristic. Therefore, this relationship can be used to measure the I DS The value reflects its junction temperature.

[0045] Figure 5(1) to Figure 5(3) , Figure 6(1) to Figure 6(2) , Figure 7(1) to Figure 7(2) It reflects the working principle of the main circuit of the present invention under three control strategies:

[0046] (I): When the control strategy is quasi-junction temperature fluctuation aging, the power cycle test process of the main circuit of the present invention is as follows:

[0047] The microprocessor controls the constant voltage source drive module to make the GaN device V GS >V threshold,GaN , corresponding to Figure 5(2)t on time period, so that it works in the active region; at this time, the continuously increasing drain-source current I DS , corresponding to Figure 5(3)t on During the time period, the current flows through the GaN device under test, which generates conduction loss and heat, causing the junction temperature of the GaN device under test to rise, corresponding to Figure 5 (1) t on If the thermocouple in the monitoring measurement circuit finds that the junction temperature of the GaN device under test rises to the preset maximum junction temperature T J,max When the negative feedback constant voltage source driving module is controlled by the microprocessor, the V GS = 0, corresponding to Figure 5 (2) t off time period, thereby shutting down the GaN device under test and enabling the heat sink to cool the GaN device under test, corresponding to Figure 5(1)t off time period; if the thermocouple in the monitoring measurement circuit finds that the shell temperature of the GaN device under test drops to the preset minimum shell temperature T C,min When the power is on, the microprocessor controls the negative feedback constant voltage source drive module to turn on the GaN device under test and turns off the heat sink to stop cooling. At this time, a new round of power cycle begins. Figure 5(1) to Figure 5(3) The timing diagram reflects the operation of the main circuit under this strategy.

[0048] (II): When the control strategy is constant shell temperature fluctuation aging, the power cycle test process of the main circuit of the present invention is as follows:

[0049] The GaN device under test operates in the active region under the action of the voltage source, and the continuously increasing drain-source current I DS The current flows through the GaN device under test, causing conduction loss and heat generation in the GaN device under test. The shell temperature of the GaN device under test is monitored by the thermocouple in the measurement circuit. When the shell temperature rises to the preset maximum shell temperature T C,maxWhen the temperature drops to the preset minimum junction temperature T, the microprocessor controls the negative feedback constant voltage source drive module to shut down the GaN device under test and enables the heat sink to cool the GaN device under test. C,min When the power cycle is on, the microprocessor controls the negative feedback constant voltage source drive module to turn on the GaN device under test, thus starting a new round of power cycle test. Figure 6(1) to Figure 6(2) The timing diagram reflects the operation of the main circuit under this strategy.

[0050] (III): When the control strategy is constant on and off time, the power cycle test process of the main circuit of the present invention is as follows:

[0051] First, the microprocessor controls the negative feedback constant voltage source drive module to turn on the device under test according to the preset time t1. After the on-time reaches t1, the microprocessor controls the negative feedback constant voltage source drive module to turn off the GaN device under test according to the preset off-time t2. After the on-time reaches t2, the microprocessor controls the negative feedback constant voltage source drive module to turn on the GaN device under test and start a new round of power cycle test. Figure 7(1) to Figure 7(2) The timing diagram reflects the operation of the main circuit under this strategy.

[0052] In summary, a power cycle main circuit for GaN power devices is used to ensure the consistency of test conditions during power cycling of the GaN devices under test, and improve the accuracy of the experimental results. At the same time, the parallel aging control strategy effectively improves the power utilization and time utilization, which is conducive to the rapid aging of multiple groups of GaN devices under test. In addition, the gate-source voltage V of the GaN device under test is regulated by adjusting the negative feedback voltage source drive according to the timing by the microprocessor. GS The method of turning on and off the GaN device under test greatly simplifies the control of the main circuit, making it simple and convenient to implement power cycle testing.

[0053] The present invention is applicable to the power cycle main circuit of GaN power semiconductor devices, and is mainly used by manufacturers or related researchers who produce GaN power semiconductor devices. Multiple parallel modules to be tested can be aged at the same time, and the aging processes of the modules to be tested are decoupled from each other and do not affect each other.

[0054] The microprocessor can adjust the negative feedback constant voltage source drive module to adjust the gate voltage of the GaN device under test in the module under test. Since the DUT is in the active area, adjust its gate-source voltage V GS The drain-source current can be changed to adjust the DUT aging power, and then the DUT aging acceleration process can be controlled. Through the measurement circuit and DUT switching mode, a variety of different aging strategies can be implemented: ①. Aging control strategy based on quasi-junction temperature fluctuation; ②. Aging control strategy based on constant shell temperature fluctuation; ③. Aging control strategy with constant on and off time.

[0055] Among them, the aging control strategy of quasi-junction temperature fluctuation refers to measuring I when the device under test is turned on. DS And through I DS The junction temperature is reflected by the relationship between the measured device and the junction temperature, and the junction temperature is reflected by measuring the device case temperature when the device under test is turned off. The difference between the maximum junction temperature and the minimum case temperature is constant during the entire power cycle; the aging control strategy of constant case temperature fluctuation refers to controlling the case temperature of the device under test to remain unchanged during each power cycle; the aging control strategy of constant on-time and off-time refers to adjusting the junction temperature fluctuation of the device under test by selecting appropriate on-time and off-time.

Claims

1. A power circulation main circuit for GaN power devices, characterized in that include: Multiple lines and voltage source V load Modules under test connected in parallel; The module to be tested includes a microprocessor, an isolation circuit, a D / A conversion circuit, an inverter, a negative feedback constant voltage source drive module, and a GaN device; The microprocessor is connected to the isolation circuit, the isolation circuit is respectively connected to the D / A conversion circuit and the inverter, the D / A conversion circuit and the inverter are both connected to the negative feedback constant voltage source drive module, and the negative feedback constant voltage source drive module is connected to the GaN device; The GaN device is connected to a measurement circuit, wherein the measurement circuit includes a thermocouple and a current sensor, and the thermocouple and the current sensor are both connected to a microprocessor; The voltage source V load , used to provide drain-source voltage for GaN devices V DS , so that the GaN device works in the active region; The microprocessor output signal enters port 1 of the negative feedback constant voltage source drive module through an isolation circuit and a D / A conversion circuit, and the microprocessor output signal enters port 2 of the negative feedback constant voltage source drive module through an isolation circuit and an inverter. By changing the output of the microprocessor, the negative feedback constant voltage source drive module can be adjusted to achieve the gate-source voltage of the GaN device under test. V GS The drain-source current flowing through the GaN device under test can be adjusted by adjusting I DS ; The microprocessor can control the negative feedback constant voltage source to change the gate-source voltage of the GaN device under test V GS , thereby achieving simultaneous aging of multiple groups of modules under test.

2. A power circulation main circuit for a GaN power device according to claim 1, characterized in that: The thermocouple is used to measure the temperature of the GaN device.

3. A power circulation main circuit for a GaN power device according to claim 1, characterized in that: The current sensor is used to measure the drain-source current of the GaN device I DS .

4. A power circulation main circuit for a GaN power device according to claim 1, characterized in that: The negative feedback constant voltage source driving module is composed of a subtractor cascaded with an integration circuit. V out The same-direction input terminal of the subtractor is led back to form negative feedback; the voltage at port 1 of the negative feedback constant voltage source driving module is inverted with the voltage at port 2.

5. A power cycle test method using a power cycle main circuit according to any one of claims 1 to 4, characterized in that: When the control strategy is quasi-junction temperature fluctuation aging, the power cycle test process of the main circuit is as follows: The GaN device under test operates in the active region under the action of a voltage source. At this time, the continuously increasing drain-source current I DS When the current flows through the GaN device under test, the GaN device under test generates conduction loss and generates heat. When the junction temperature rises to the preset maximum junction temperature, the negative feedback constant voltage source drive module is controlled by the microprocessor to turn off the GaN device under test. After the GaN device under test is turned off, it is cooled by the heat sink. When the measured shell temperature reaches the preset minimum shell temperature, the negative feedback constant voltage source drive module is controlled by the microprocessor to turn on the GaN device under test, thereby starting a new round of power cycle.

6. A power cycle test method using a power cycle main circuit according to any one of claims 1 to 4, characterized in that: When the control strategy is constant shell temperature fluctuation aging, the power cycle test process of the main circuit is as follows: The GaN device under test operates in the active region under the action of a voltage source, and the drain-source current continues to increase. I DS The current flows through the GaN device under test, causing conduction loss and heat generation in the GaN device under test. The shell temperature of the GaN device under test is monitored by the thermocouple in the measurement circuit. When the shell temperature rises to the preset maximum shell temperature, the microprocessor controls the negative feedback constant voltage source drive module to shut down the GaN device under test. The GaN device under test is cooled down by the heat sink. When the shell temperature is found to drop to the preset minimum junction temperature through the thermocouple in the measurement circuit, the microprocessor controls the negative feedback constant voltage source drive module to turn on the GaN device under test, thereby starting a new round of power cycle test.

7. A power cycle test method using a power cycle main circuit according to any one of claims 1 to 4, characterized in that: When the control strategy is constant on and off time, the power cycle test process of the main circuit is as follows: First, the microprocessor controls the negative feedback constant voltage source drive module to follow the preset time t 1 Turn on the device under test and wait for the on-time to reach t 1, the microprocessor controls the negative feedback constant voltage source drive module to turn off according to the preset off time t 2 Turn off the GaN device under test and wait for the on-time to reach t 2, the microprocessor controls the negative feedback constant voltage source drive module to turn on the GaN device under test and start a new round of power cycle test.

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