Thermal measurement switching loss circuit and method for bottom thermally dissipated gan devices

Abstract

The application provides a heat measurement switch loss circuit and method suitable for a bottom heat dissipation GaN device, in which the drain of a to-be-measured GaN device T1 and the drain of an auxiliary GaN device T3 are connected to the positive electrode of a voltage source V DC , the source of T1 is connected to the drain of an auxiliary GaN device T2, the source of T3 is connected to the drain of an auxiliary GaN device T4, the sources of T2 and T4 are both connected to the negative electrode of the voltage source V DC , a first node N1 is included between the source of T1 and the drain of T2, a second node N2 is included between the source of T3 and the drain of T4, the two ends of an inductor L are respectively connected to N1 and N2, and a capacitor C DC is connected in parallel to the voltage source V DC . For the bottom heat dissipation to-be-measured GaN device T1, the application selects the top heat dissipation auxiliary GaN devices T2, T3 and T4 when testing by using the heat measurement switch loss circuit, so that most of the loss heat of T1 is on the PCB, and the heat loss measurement precision of the to-be-measured GaN device T1 is improved.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor switching technology, specifically relating to a circuit and method for measuring the switching loss of bottom-heat-dissipating GaN devices. Background Technology

[0002] Currently, the demand for high power density and high efficiency in power converters is becoming increasingly urgent. One way to improve power density is to increase the switching frequency, thereby reducing the size of the output capacitor and inductor. Since the performance of Si-based devices has reached its theoretical limit with technological advancements, their switching speed is insufficient to support the high-frequency switching requirements of power converters. In contrast, third-generation semiconductor GaN devices offer faster switching frequencies, lower on-resistance, and higher breakdown voltage, and are therefore widely used in power converters. However, accurately evaluating the switching losses of GaN devices remains a problem that urgently needs to be solved by those skilled in the art.

[0003] In related technologies, dual-pulse circuits are mainly used to evaluate the switching losses of GaN devices. However, dual-pulse circuits are more suitable for Si-based devices with low switching speeds and insensitivity to parasitic parameters. Studies have shown that when using dual-pulse circuits to test the switching losses of silicon carbide and gallium nitride devices, the error can be as high as 40%.

[0004] In addition, there is a thermal testing method in the related technology that is suitable for silicon carbide devices in TO220 packages, but gallium nitride devices are mostly surface-mount packages in order to reduce parasitic parameters, so this thermal testing method is not suitable for gallium nitride devices. Summary of the Invention

[0005] To address the aforementioned problems in the prior art, this invention provides a circuit and method for measuring the switching loss of bottom-heat-dissipating GaN devices.

[0006] In a first aspect, the present invention provides a thermal measurement switching loss circuit suitable for bottom-heat-dissipating GaN devices, including a voltage source V DC Capacitor C DC ,inductance L The gallium nitride device under test, T1, and auxiliary gallium nitride devices, T2, T3, and T4, are included.

[0007] The drain of the gallium nitride device under test T1 and the drain of the auxiliary gallium nitride device T3 are connected to the voltage source V. DC The positive terminal of the device is connected to the source of the gallium nitride device under test (GNT) T1, and the drain of the auxiliary GNT T2 is connected to the source of the auxiliary GNT T3, and the drain of the auxiliary GNT T4 is connected to the source of the auxiliary GNT T2 and T4. The sources of the auxiliary GNT devices T2 and T4 are both connected to the voltage source V. DCThe negative electrode of the GaN device under test (T1) and the drain of the auxiliary GaN device (T2) are connected by a first node N1, and the source of the auxiliary GaN device (T3) and the drain of the auxiliary GaN device (T4) are connected by a second node N2. The inductor... L The two ends are connected to the first node N1 and the second node N2 respectively, and the capacitor C DC With voltage source V DC The devices are connected in parallel, and the gallium nitride device under test T1 is a bottom package.

[0008] In one embodiment of the present invention, auxiliary gallium nitride device T2, auxiliary gallium nitride device T3 and auxiliary gallium nitride device T4 are all top-packaged.

[0009] In one embodiment of the present invention, three finned heat sinks are further included; wherein,

[0010] The voltage source V DC Capacitor C DC ,inductance L The gallium nitride device under test T1 and auxiliary gallium nitride devices T2, T3 and T4 are located on one side of the printed circuit board, and the three finned heat sinks are located on the other side of the printed circuit board corresponding to the auxiliary gallium nitride devices T2, T3 and T4 respectively.

[0011] In one embodiment of the present invention, the top of the gallium nitride device T1 under test is wrapped with a thermally resistive material.

[0012] In one embodiment of the present invention, the thermal resistance material is plastic.

[0013] In a second aspect, the present invention provides a method for measuring the switching loss of a bottom-heat-dissipated GaN device, applied to the circuit for measuring the switching loss of a bottom-heat-dissipated GaN device described in the first aspect, comprising:

[0014] After fixing the gallium nitride device T1 under test in the thermal measurement switching loss circuit onto the copper heat sink of the thermal testing device, the thermal measurement switching loss circuit is turned on; wherein, the thermal testing device includes an air supply module and a cavity connected to the air outlet of the air supply module, and the copper heat sink is located on the surface of the cavity.

[0015] After the thermal measurement switching loss circuit reaches a thermally stable state, the temperature at the first test point located on the side of the copper heat sink near the air supply module is measured. T air,in The temperature at a second test point located on the side of the copper radiator furthest from the air supply module was measured. T air,out ;

[0016] Based on the temperature at the first test pointT air,in and the temperature at the second test point T air,out The thermal measurement switching loss of the gallium nitride device T1 under test was calculated.

[0017] In one embodiment of the present invention, based on the temperature of the first test point T air,in and the temperature at the second test point T air,out The steps for calculating the thermal measurement switching loss of the gallium nitride device T1 under test include:

[0018] Calculate the temperature at the second test point. T air,out Temperature at a test point T air,in The difference is used to obtain the thermal measurement switching loss result of the gallium nitride device T1 under test.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] This invention provides a thermal measurement switching loss circuit and method for bottom-heated GaN devices. For the bottom-heated GaN device T1 under test, this invention selects top-heated auxiliary GaN devices T2, T3, and T4 when testing using the thermal measurement switching loss circuit. In this way, the three top-heated auxiliary tubes will have very little heat flow through the bottom PCB board, and most of the heat loss on the PCB board is the heat loss of the GaN device T1 under test. This helps to improve the thermal loss measurement accuracy of the GaN device T1 under test.

[0021] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a dual-pulse test circuit in related technologies;

[0023] Figure 2 This is a schematic diagram of a thermal measurement switching loss circuit for bottom-heat-dissipating GaN devices provided in an embodiment of the present invention;

[0024] Figure 3 This is a schematic diagram of the gallium nitride device under test and the auxiliary gallium nitride device provided in an embodiment of the present invention;

[0025] Figure 4 This is a schematic diagram of the structure of the other side of the printed circuit board provided in an embodiment of the present invention;

[0026] Figure 5 This is a flowchart of a method for measuring the switching loss of bottom-heat-dissipating GaN devices, provided in an embodiment of the present invention.

[0027] Figure 6 This is a schematic diagram of a thermal testing device provided in an embodiment of the present invention;

[0028] Figure 7 This is a schematic diagram of the temperature field distribution provided in an embodiment of the present invention;

[0029] Figure 8 This is a schematic diagram of the temperature field distribution on the other side of the printed circuit board provided in an embodiment of the present invention. Detailed Implementation

[0030] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.

[0031] Figure 1 This is a schematic diagram of a dual-pulse test circuit in related technologies. Specifically, as shown... Figure 1 As shown, when evaluating switching losses using a dual-pulse test circuit, two pulse signals need to be supplied to the transistor under test (S1). The first pulse signal is used to test the turn-off loss, and the second pulse signal is used to test the turn-on loss. Specifically, S1 is first turned on, and S2 is turned off, then the inductor... L 1. Charge the circuit until the required test current is reached. Then, test the turn-off loss (S1 is turned off) at the falling edge of the first pulse, and simultaneously turn on S2 to form a freewheeling circuit. Then, turn on S1 and turn off S2, and test the turn-on loss at the rising edge of the second pulse.

[0032] Because the freewheeling side element S2 body diode switches from on to off during the second turn-on, its reverse recovery characteristics are poor, which will increase the measured turn-on loss. Therefore, the error is very large when using the above-mentioned dual-pulse test circuit to test wide bandgap semiconductors, about 40%.

[0033] In view of this, the present invention provides a circuit and method for measuring the switching loss of bottom-heat-dissipating GaN devices.

[0034] Figure 2 This is a schematic diagram of a thermal measurement switching loss circuit for bottom-heat-dissipating GaN devices provided in an embodiment of the present invention. Figure 2 As shown, this embodiment of the invention provides a thermal measurement switching loss circuit suitable for bottom-heat-dissipating GaN devices, including a voltage source V. DC Capacitor C DC ,inductance L The gallium nitride device under test, T1, and auxiliary gallium nitride devices, T2, T3, and T4, are included.

[0035] The drain of the gallium nitride device under test T1 and the drain of the auxiliary gallium nitride device T3 are connected to the voltage source V. DCThe positive terminal of the device is connected to the source of the gallium nitride device under test (GNT) T1, and the drain of the auxiliary GNT T2 is connected to the source of the auxiliary GNT T3, and the drain of the auxiliary GNT T4 is connected to the source of the auxiliary GNT T2 and T4. The sources of the auxiliary GNT devices T2 and T4 are both connected to the voltage source V. DC The negative electrode of the GaN device under test (T1) and the drain of the auxiliary GaN device (T2) are connected by a first node N1, and the source of the auxiliary GaN device (T3) and the drain of the auxiliary GaN device (T4) are connected by a second node N2. The inductor... L The two ends are connected to the first node N1 and the second node N2 respectively, and the capacitor C DC With voltage source V DC The devices are connected in parallel, and the gallium nitride device under test, T1, is a bottom package.

[0036] Specifically, this embodiment adopts Figure 2 The full-bridge topology shown is used for testing. The gallium nitride device under test (GaN) T1 is a bottom-packaged device. The gates of GaN T1 and auxiliary GaN devices T2, T3, and T4 are all connected to the driving circuit. During the test, the above-mentioned thermal measurement switching loss circuit includes four operating stages: t1 to t4. In the t1 operating stage, GaN T1 and auxiliary GaN device T4 are turned on, while auxiliary GaN devices T2 and T3 are turned off. In the t2 operating stage, auxiliary GaN devices T2 and T4 are turned on, while GaN T1 and auxiliary GaN device T3 are turned off. In the t3 operating stage, auxiliary GaN devices T2 and T3 are turned on, while GaN T1 and auxiliary GaN device T4 are turned off. In the t4 operating stage, auxiliary GaN devices T2 and T4 are turned on, while GaN T1 and auxiliary GaN device T3 are turned off.

[0037] It should be understood that the switching loss of the gallium nitride device under test (DUT) T1 is generated during its turn-on to turn-off process. However, the duration of a typical circuit operating cycle is only on the order of microseconds, making it difficult to measure the losses generated by the DUT during the turn-on to turn-off period. Analysis of the various operating stages of the circuit shows that the DUT T1 only operates during the t1 operating stage. This design minimizes the duty cycle of the DUT (i.e., the gallium nitride device under test T1). In other words, this embodiment, through the above operating process, can reduce the on-time of the gallium nitride device T1 while ensuring continuous circuit operation, thereby reducing the switching loss error when testing the gallium nitride device T1.

[0038] Figure 3 This is a schematic diagram of the gallium nitride device under test and the auxiliary gallium nitride device provided in an embodiment of the present invention. Optionally, as shown... Figure 3 As shown, auxiliary gallium nitride device T2, auxiliary gallium nitride device T3 and auxiliary gallium nitride device T4 are all top-packaged.

[0039] Specifically, voltage source V DC Capacitor C DC ,inductance L The gallium nitride device under test (GaN) T1 and auxiliary GaN devices T2, T3, and T4 are located on one side of the printed circuit board. Since the GaN device under test T1 is bottom-heated, the heat it loses can reach the other side of the PCB. However, the auxiliary GaN devices T2, T3, and T4 are all top-packaged GaN devices. In this way, very little heat flow will be conducted to the other side of the PCB from the three top-heated auxiliary tubes. That is to say, most of the heat loss of the GaN device under test T1 is on the PCB, which helps to improve the measurement accuracy of the heat loss of the GaN device under test T1.

[0040] Furthermore, the aforementioned thermal measurement switching loss circuit for bottom-heat-dissipated GaN devices also includes three finned heat sinks; wherein,

[0041] Voltage source V DC Capacitor C DC ,inductance L The gallium nitride device under test (GaN) T1 and auxiliary GaN devices T2, T3, and T4 are located on one side of the printed circuit board, and three finned heat sinks are located on the other side of the printed circuit board. The three finned heat sinks are respectively set to correspond to the auxiliary GaN devices T2, T3, and T4.

[0042] Figure 4 This is a schematic diagram of the other side of the printed circuit board provided in an embodiment of the present invention. Specifically, in order to prevent the heat from the auxiliary gallium nitride device from passing through the bottom PCB board, this embodiment provides a structure on the other side of the PCB board as shown in the diagram. Figure 4 The three finned heat sinks shown are respectively paired with auxiliary gallium nitride devices T2, T3 and T4, thereby further reducing the top thermal resistance by adding heat sinks to the top heat dissipation tube.

[0043] In this embodiment, the top of the gallium nitride device under test (GaN) T1 is wrapped with a thermally resistive material, which can optionally be plastic. By wrapping the top of the GaN T1, which dissipates heat at the bottom, with a thermally resistive material, the heat dissipated can be prevented from escaping from the top, further improving the measurement accuracy of the switching loss of the GaN T1.

[0044] Of course, other high thermal resistance materials may be selected in some other embodiments of this application, and this application does not limit them.

[0045] Figure 5 This is a flowchart of a method for measuring the switching loss of bottom-heat-dissipated GaN devices, provided by an embodiment of the present invention. Please refer to [link to flowchart documentation]. Figure 5 This invention also provides a method for measuring the switching loss of a bottom-heat-dissipated GaN device, applied to the aforementioned circuit for measuring the switching loss of a bottom-heat-dissipated GaN device, comprising:

[0046] S1. After fixing the gallium nitride device T1 under test in the thermal measurement switching loss circuit onto the copper heat sink of the thermal testing device, turn on the thermal measurement switching loss circuit; wherein, the thermal testing device includes an air supply module and a cavity connected to the air outlet of the air supply module, and the copper heat sink is located on the surface of the cavity.

[0047] S2. After the switching loss measurement circuit reaches thermal stability, measure the temperature at the first test point located on the side of the copper heat sink closest to the air supply module. T air,in The temperature at a second test point located on the side of the copper radiator furthest from the air supply module was measured. T air,out ;

[0048] S3, Based on the temperature of the first test point T air,in and the temperature at the second test point T air,out The thermal measurement switching loss of the gallium nitride device T1 under test was calculated.

[0049] Figure 6 This is a schematic diagram of a thermal testing apparatus provided in an embodiment of the present invention. Figure 6 As shown, the thermal testing apparatus includes an air supply module and a cavity. The cavity is connected to the air outlet of the air supply module, and a copper heat sink is provided on the outer surface of the cavity. Please continue reading... Figure 2 The gallium nitride device under test (GaN) T1 is soldered onto a copper heat sink. Then, the thermal measurement switching loss circuit is turned on. The thermal measurement switching loss circuit includes operating stages t1, t2, t3, and t4. In operating stage t1, GaN T1 and auxiliary GaN T4 are turned on, while auxiliary GaN devices T2 and T3 are turned off. In operating stage t2, auxiliary GaN devices T2 and T4 are turned on, while GaN T1 and auxiliary GaN device T3 are turned off. In operating stage t3, auxiliary GaN devices T2 and T3 are turned on, while GaN T1 and auxiliary GaN device T4 are turned off. In operating stage t4, auxiliary GaN devices T2 and T4 are turned on, while GaN T1 and auxiliary GaN device T3 are turned off.

[0050] Optionally, after multiple operating cycles t1 to t4, the circuit will reach a thermally stable state. During the above-mentioned operation, the heat from the gallium nitride device under test (GaN) T1 is dissipated into the cavity through the copper heat sink. The copper heat sink has a first test point on the side near the air supply module and a second test point on the side away from the air supply module. The air supplied by the air supply module will sequentially pass through the first test point, the copper heat sink area, and the second test point. Because the heat dissipated by the GaN device under test T1 is concentrated at the copper heat sink, the temperature of the air supplied by the air supply module at the first test point is... T air,in And the temperature at the second test point T air,out There are variations; this embodiment is based on the temperature of the first test point. T air,in and the temperature at the second test point T air,out The thermal measurement switching loss of the gallium nitride device T1 under test can be calculated.

[0051] Specifically, in step S3 above, based on the temperature of the first test point... T air,in and the temperature at the second test point T air,out The steps for calculating the thermal measurement switching loss of the gallium nitride device T1 under test include:

[0052] Calculate the temperature at the second test point. T air,out Temperature at a test point T air,in The difference is used to obtain the thermal measurement switching loss result of the gallium nitride device T1 under test.

[0053] The following simulation experiment further illustrates the thermal measurement switching loss circuit and method for bottom-heat-dissipating GaN devices provided by this invention.

[0054] Specifically, this embodiment simulates a thermal measurement switching loss circuit suitable for bottom-heat-dissipated GaN devices. Figure 7 This is a schematic diagram of the temperature field distribution provided in an embodiment of the present invention, such as... Figure 7 As shown, most of the heat from the auxiliary GaN device was extracted, while the top of the GaN device under test was covered with a high thermal resistance material, preventing heat from being dissipated through the top and causing it to dissipate entirely through the bottom. Figure 8 This is a schematic diagram of the temperature field distribution on the other side of the printed circuit board provided in an embodiment of the present invention. From Figure 8 As can be seen, most of the heat from the GaN device under test is dissipated from the bottom.

[0055] As can be seen from the above embodiments, the beneficial effects of the present invention are as follows:

[0056] This invention provides a thermal measurement switching loss circuit and method for bottom-heated GaN devices. For the bottom-heated GaN device T1 under test, this invention selects top-heated auxiliary GaN devices T2, T3, and T4 when testing using the thermal measurement switching loss circuit. In this way, the three top-heated auxiliary tubes will have very little heat flow through the bottom PCB board, and most of the heat loss on the PCB board is the heat loss of the GaN device T1 under test. This helps to improve the thermal loss measurement accuracy of the GaN device T1 under test.

[0057] In the description of this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0058] Although this application has been described herein in conjunction with various embodiments, other variations of the disclosed embodiments can be understood and implemented by those skilled in the art in carrying out the claimed application by reviewing the accompanying drawings, the disclosure, and the appended claims.

[0059] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A thermal measurement switching loss circuit suitable for bottom-heat-dissipating GaN devices, characterized in that, Including voltage source V DC Capacitor C DC ,inductance L The system consists of the gallium nitride device under test (GaN) T1, auxiliary GaN devices T2, T3, and T4, and three finned heat sinks; among which, The drain of the gallium nitride device under test T1 and the drain of the auxiliary gallium nitride device T3 are connected to the voltage source V. DC The positive terminal of the device is connected to the source of the gallium nitride device under test (GNT) T1, and the drain of the auxiliary GNT T2 is connected to the source of the auxiliary GNT T3, and the drain of the auxiliary GNT T4 is connected to the source of the auxiliary GNT T2 and T4. The sources of the auxiliary GNT devices T2 and T4 are both connected to the voltage source V. DC The negative electrode of the GaN device under test (T1) and the drain of the auxiliary GaN device (T2) are connected by a first node N1, and the source of the auxiliary GaN device (T3) and the drain of the auxiliary GaN device (T4) are connected by a second node N2. The inductor... L The two ends are connected to the first node N1 and the second node N2 respectively, and the capacitor C DC With voltage source V DC The GaN device under test, T1, is a bottom package; the auxiliary GaN devices T2, T3, and T4 are all top packages. The voltage source V DC Capacitor C DC ,inductance L The gallium nitride device under test T1 and auxiliary gallium nitride devices T2, T3 and T4 are located on one side of the printed circuit board, and the three finned heat sinks are located on the other side of the printed circuit board corresponding to the auxiliary gallium nitride devices T2, T3 and T4 respectively.

2. The thermal measurement switching loss circuit for bottom-heat-dissipating GaN devices according to claim 1, characterized in that, The top of the gallium nitride device T1 under test is covered with a thermally resistive material.

3. The thermal measurement switching loss circuit for bottom-heat-dissipating GaN devices according to claim 2, characterized in that, The thermal resistance material is plastic.

4. A method for measuring the switching loss of bottom-heat-dissipating GaN devices, characterized in that, The thermal measurement switching loss circuit for bottom-heat-dissipating GaN devices, as described in any one of claims 1 to 3, comprises: After fixing the gallium nitride device T1 under test in the thermal measurement switching loss circuit onto the copper heat sink of the thermal testing device, the thermal measurement switching loss circuit is turned on; wherein, the thermal testing device includes an air supply module and a cavity connected to the air outlet of the air supply module, and the copper heat sink is located on the surface of the cavity. After the thermal measurement switching loss circuit reaches a thermally stable state, the temperature at the first test point located on the side of the copper heat sink near the air supply module is measured. T air,in The temperature at a second test point located on the side of the copper radiator furthest from the air supply module was measured. T air,out ; Based on the temperature at the first test point T air,in and the temperature at the second test point T air,out The thermal measurement switching loss of the gallium nitride device T1 under test was calculated.

5. The method for measuring the switching loss of bottom-heat-dissipating GaN devices according to claim 4, characterized in that, Based on the temperature at the first test point T air,in and the temperature at the second test point T air,out The steps for calculating the thermal measurement switching loss of the gallium nitride device T1 under test include: Calculate the temperature at the second test point. T air,out Temperature at a test point T air,in The difference is used to obtain the thermal measurement switching loss result of the gallium nitride device T1 under test.

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