GaN HEMT device three-state driving circuit

Abstract

The present invention belongs to the field of power semiconductor device driving, and specifically relates to a three-state driving circuit of a GaN HEMT device, which aims to solve the problem that the reverse conduction voltage drop of the GaN HEMT device is high, resulting in large losses in the freewheeling process during the dead time. The present invention includes: a GaN HEMT three-state driving circuit, which uses an SR latch to realize the recognition of the dead time after the GaN HEMT is turned off, and reduces the reverse conduction voltage drop of the device by controlling the gate drive voltage of the GaN HEMT device in the freewheeling stage after the shutdown, thereby reducing the freewheeling loss and improving the efficiency, and keeping the GaN HEMT in a normal off state during the dead time before turning on, thereby improving the reliability and flexibility of the drive. The present invention fundamentally solves the problem of large freewheeling losses caused by high reverse conduction voltage drop, and has a simple structure and is not limited by circuit topology.

Description

Technical Field

[0001] The invention belongs to the field of power semiconductor device driving, and in particular relates to a GaN HEMT device tri-state driving circuit. Background Art

[0002] GaN HEMT devices have broad application prospects in the field of high-efficiency, high-frequency power conversion due to their superior performance such as high breakdown field strength and low on-resistance. The device characteristics of GaN HEMT devices are quite different from those of silicon-based MOSFETs, and their gate drive technology has been a hot research topic in academia and industry in recent years.

[0003] GaN HEMT devices are different from silicon-based MOSFETs in that they do not have a reverse-parallel body diode. However, although there is no reverse recovery process of the body diode, GaN HEMT devices exhibit a higher on-state voltage drop during the dead time, which will result in additional efficiency loss. Figure 1 As shown in FIG. 1 , a schematic diagram of a prior art dual active bridge (DAB) topology structure is shown. Figure 1 Taking the topology of as an example, the conventional single-phase shift control is adopted, and its typical switching waveform is as follows Figure 2 As shown, during the dead time of the driving signal ( Figure 2 The shaded part (times t0-t1, t3-t4, t6-t7) has the primary current i Ls With a high current peak, after the four switches on the primary side are turned off, it needs to flow in the reverse direction through the parasitic diode of the switch tube for freewheeling. Due to the reverse conduction voltage drop (V SD ) is high, resulting in large conduction losses during the dead time and severe device heating.

[0004] Although the adaptive dead time control strategy can reduce the follow-on time and the follow-on loss to a certain extent by adjusting the dead time, it cannot fundamentally solve the problem of large follow-on loss of GaN HEMT devices. Moreover, the adjustment of the dead time will also affect the soft switching and other working processes of the converter, affecting the efficient operation of the converter.

[0005] Therefore, how to reduce the dead time follow-on loss of GaN HEMT devices has become one of the key issues for the efficient application of GaN HEMT devices. Summary of the invention

[0006] In order to solve the above-mentioned problem in the prior art, that is, the reverse conduction voltage drop of the GaN HEMT device is relatively high, resulting in a large loss in the freewheeling process during the dead time, the present invention provides a GaN HEMT device three-state drive circuit, the GaN HEMT device three-state drive circuit includes an input end of a PWM1 drive signal, an input end of a PWM2 drive signal, an SR latch, a freewheeling drive switch tube, a freewheeling drive power supply, a conduction drive half bridge, a conduction drive power supply and a freewheeling drive anti-reverse diode;

[0007] The set end of the SR latch is connected to the input end of the PWM1 drive signal, the reset end is connected to the input end of the PWM2 drive signal, and the output end is connected to the gate of the freewheeling drive switch tube;

[0008] The drain of the freewheeling drive switch tube is connected to the positive electrode of the freewheeling drive power supply, and the source is connected to the gate of the GaN HEMT device to be driven through the freewheeling drive anti-reverse diode;

[0009] The conduction drive half bridge includes an upper tube and a lower tube, the gate of the upper tube is connected to the input end of the PWM1 drive signal, the drain is connected to the positive electrode of the conduction drive power supply, the gate of the lower tube is connected to the input end of the PWM2 drive signal, and the source of the upper tube and the drain of the lower tube are connected together to the gate of the GaN HEMT device to be driven;

[0010] The negative electrode of the freewheeling driving power supply, the negative electrode of the conduction driving power supply and the source electrode of the lower tube are all grounded.

[0011] In some preferred embodiments, both the PWM1 driving signal and the PWM2 driving signal have a dead time, and the signals outside the dead time are complementary.

[0012] In some preferred embodiments, the SR latch drives the freewheeling drive switch tube to turn on during the dead time after the GaN HEMT device to be driven is turned off, and keeps the freewheeling drive switch tube turned off during the dead time before the GaN HEMT device to be driven is turned on.

[0013] In some preferred embodiments, the PWM1 driving signal, the PWM2 driving signal and the timing signal between the SR latch are used to control the GaN HEMT device to be driven to be in the off state, the on state or the freewheeling state.

[0014] In some preferred embodiments, the conduction drive half-bridge is used to drive the GaN HEMT device to be driven under the timing signal between the PWM1 drive signal, the PWM2 drive signal and the SR latch, so that the GaN HEMT device to be driven is in the on state or the off state; the freewheeling drive switch tube is used to drive the GaN HEMT device to be driven under the timing signal between the PWM1 drive signal, the PWM2 drive signal and the SR latch, so that the GaN HEMT device to be driven is in the freewheeling state.

[0015] In some preferred embodiments, the freewheeling drive switch tube is turned on in the freewheeling stage after the GaN HEMT device to be driven is turned off, and is used to apply the voltage of the freewheeling drive power supply to the gate of the GaN HEMT device to be driven, so that the GaN HEMT device to be driven remains turned off in the freewheeling state, and the reverse conduction voltage drop of the GaN HEMT device to be driven is reduced.

[0016] In some preferred embodiments, the voltage of the freewheeling driving power supply is less than the gate turn-on voltage of the GaN HEMT device to be driven.

[0017] In some preferred embodiments, the conduction driving half-bridge is used to apply the voltage of the conduction driving power supply to the gate of the GaN HEMT device to be driven, so that the GaN HEMT device to be driven is in a conduction state.

[0018] In some preferred embodiments, the freewheeling drive anti-reverse diode has an anode connected to the source of the freewheeling drive switch tube, and a cathode connected to the gate of the GaN HEMT device to be driven.

[0019] In some preferred embodiments, the freewheeling drive anti-reverse diode is used to prevent a short circuit caused by the voltage of the on-state drive power supply being applied to the freewheeling drive power supply when the GaN HEMT device to be driven is in the on-state.

[0020] Beneficial effects of the present invention:

[0021] (1) The GaN HEMT device tri-state driving circuit of the present invention applies a driving voltage lower than the turn-on threshold to the gate of the GaN HEMT device to be driven during the dead time, thereby keeping the device in the off state and reducing the reverse tube voltage drop, thereby fundamentally solving the problem of large freewheeling loss caused by high reverse conduction voltage drop.

[0022] (2) The GaN HEMT device tri-state driving circuit of the present invention uses an SR latch to realize the recognition of the dead time after the GaN HEMT device to be driven is turned off, so that the GaN HEMT device to be driven can maintain a normal off state during the dead time before being turned on, thereby improving the reliability and flexibility of the driving.

[0023] (3) The three-state driving circuit of the GaN HEMT device of the present invention does not affect the adjustment of the circuit dead time, has no requirements for the modulation strategy of the circuit, and is not limited by the circuit topology. It is suitable for single-tube, half-bridge, multi-level and other circuit topologies, and has rich application scenarios.

[0024] (4) The GaN HEMT device tri-state driving circuit of the present invention only adds an SR latch and a driving switch tube in the freewheeling stage on the basis of a conventional GaN HEMT device driving circuit, and has a simple structure, low cost, high reliability, and is easy to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

[0026] Figure 1 It is a schematic diagram of a prior art dual active bridge (DAB) topology structure;

[0027] Figure 2 It is a typical switching waveform diagram of the prior art dual active bridge (DAB) topology using single phase shift control;

[0028] Figure 3 It is a schematic diagram of the driving circuit structure of an embodiment of a three-state driving circuit of a GaN HEMT device of the present invention;

[0029] Figure 4 This is a switching waveform principle diagram of an embodiment of a three-state driving circuit for a GaN HEMT device of the present invention;

[0030] Figure 5 It is a switching waveform diagram of a single phase shift control DAB circuit of an embodiment of a GaN HEMT device three-state driving circuit of the present invention. DETAILED DESCRIPTION

[0031] The present application will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. It is also necessary to explain that, for ease of description, only the parts related to the relevant invention are shown in the accompanying drawings.

[0032] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0033] The present invention provides a three-state driving circuit for a GaN HEMT device, which reduces the reverse conduction voltage drop of the GaN HEMT device by controlling the gate driving voltage of the GaN HEMT device in the follow-up stage after the device is turned off, thereby reducing the follow-up loss of the GaN HEMT device and improving the efficiency.

[0034] A GaN HEMT device tri-state drive circuit of the present invention comprises an input end of a PWM1 drive signal, an input end of a PWM2 drive signal, an SR latch, a freewheeling drive switch tube, a freewheeling drive power supply, a conduction drive half bridge, a conduction drive power supply and a freewheeling drive anti-reverse diode;

[0035] The set end of the SR latch is connected to the input end of the PWM1 drive signal, the reset end is connected to the input end of the PWM2 drive signal, and the output end is connected to the gate of the freewheeling drive switch tube;

[0036] The drain of the freewheeling drive switch tube is connected to the positive electrode of the freewheeling drive power supply, and the source is connected to the gate of the GaN HEMT device to be driven through the freewheeling drive anti-reverse diode;

[0037] The conduction drive half bridge includes an upper tube and a lower tube, the gate of the upper tube is connected to the input end of the PWM1 drive signal, the drain is connected to the positive electrode of the conduction drive power supply, the gate of the lower tube is connected to the input end of the PWM2 drive signal, and the source of the upper tube and the drain of the lower tube are connected together to the gate of the GaN HEMT device to be driven;

[0038] The negative electrode of the freewheeling driving power supply, the negative electrode of the conduction driving power supply and the source electrode of the lower tube are all grounded.

[0039] In order to more clearly explain the GaN HEMT device tri-state driving circuit of the present invention, Figure 3 Each module in the embodiment of the present invention is described in detail.

[0040] The GaN HEMT device tri-state driving circuit of the first embodiment of the present invention includes an input terminal 1 of a PWM1 driving signal, an input terminal 2 of a PWM2 driving signal, an SR latch 3, a freewheeling driving switch tube 5, a freewheeling driving power supply 4, a conduction driving half bridge 7, a conduction driving power supply 6 and a freewheeling driving anti-reverse diode 8. Each module is described in detail as follows:

[0041] The set end of the SR latch 3 is connected to the input end 1 of the PWM1 drive signal, the reset end is connected to the input end 2 of the PWM2 drive signal, and the output end is connected to the gate of the freewheeling drive switch tube 5;

[0042] The drain of the freewheeling driving switch tube 5 is connected to the positive electrode of the freewheeling driving power supply 4, and the source is connected to the gate of the GaN HEMT device 9 to be driven through the freewheeling driving anti-reverse diode 8;

[0043] The conduction driving half bridge 7 comprises an upper tube and a lower tube, the gate of the upper tube is connected to the input terminal 1 of the PWM1 driving signal, the drain is connected to the positive electrode of the conduction driving power supply 6, the gate of the lower tube is connected to the input terminal 2 of the PWM2 driving signal, and the source of the upper tube and the drain of the lower tube are connected together to the gate of the GaN HEMT device 9 to be driven;

[0044] The negative electrode of the freewheeling driving power supply 4, the negative electrode of the conduction driving power supply 6 and the source electrode of the lower tube are all grounded.

[0045] like Figure 4 As shown in FIG. 1 , a switching waveform principle diagram of an embodiment of a three-state driving circuit for a GaN HEMT device of the present invention is shown. The two driving signals PWM1 and PWM2 are two driving signals with dead time and complementary signals outside the dead time. Figure 4 In the figure, the dead time is t0-t1 and t2-t3 respectively. For the GaN HEMT device 9 to be driven, the time t2-t3 is the freewheeling stage, and the time t0-t1 is the conventional turn-off stage. Therefore, in order to ensure the reliability and applicability of the drive (such as the half-bridge topology), the gate voltage V of the GaN HEMT device 9 to be driven should be controlled only within the time t2-t3. GS And reduce its follow-up loss.

[0046] The SR latch 3 drives the freewheeling drive switch tube 5 to turn on during the dead time after the GaN HEMT device 9 to be driven is turned off, and keeps the freewheeling drive switch tube 5 turned off during the dead time before the GaN HEMT device 9 to be driven is turned on. That is, the SR latch 3 turns on the freewheeling drive switch tube 5 during the dead time t2-t3 after the GaN HEMT device 9 to be driven is turned off, and keeps the freewheeling drive switch tube 5 turned off during the dead time t0-t1 before the GaN HEMT device 9 to be driven is turned on, according to the two drive signals PWM1 and PWM2.

[0047] The timing signal between the PWM1 driving signal, the PWM2 driving signal and the SR latch is used to control the GaN HEMT device 9 to be driven to be in the off state, the on state or the freewheeling state.

[0048] like Figure 3As shown, the on-state and off-state of the GaN HEMT device 9 to be driven are driven by the on-drive half-bridge 7 , and the freewheeling state of the GaN HEMT device 9 to be driven is driven by the freewheeling drive switch tube 4 .

[0049] The on-drive half-bridge 7 is used to drive the GaN HEMT device 9 to be driven under the timing signal between the PWM1 drive signal, the PWM2 drive signal and the SR latch 3, so that the GaN HEMT device 9 to be driven is in the on state or the off state; the freewheeling drive switch tube 5 is used to drive the GaN HEMT device 9 to be driven under the timing signal between the PWM1 drive signal, the PWM2 drive signal and the SR latch 3, so that the GaN HEMT device 9 to be driven is in the freewheeling state.

[0050] The freewheeling drive switch 5 is turned on in the freewheeling stage after the GaN HEMT device 9 to be driven is turned off, and is used to apply the voltage of the freewheeling drive power supply 4 to the gate of the GaN HEMT device 9 to be driven (i.e., the gate voltage V applied to the GaN HEMT device 9 to be driven). GS ), so that the GaN HEMT device 9 to be driven remains turned off in the freewheeling state, and the reverse conduction voltage drop of the GaN HEMT device 9 to be driven is reduced.

[0051] The gate threshold voltage of conventional GaN HEMT devices (such as the GS66516T device of GaN Systems) is relatively low, generally about 1.3V. In the present invention, it is necessary to make the voltage of the freewheeling driving power supply 4 lower than the gate turn-on voltage of the GaN HEMT device 9 to be driven. In this embodiment, the freewheeling driving power supply 4 is set to 0.9V. Therefore, when the freewheeling driving power supply 4 is applied to the gate voltage V of the GaN HEMT device 9 to be driven in the freewheeling state, GS When the GaN HEMT device 9 to be driven is kept off, and its reverse voltage drop is small.

[0052] In the embodiment of the present invention, in order to make the GaN HEMT device GS66516T fully turned on, the voltage of the on-state driving power supply 6 is set to 6V, and the on-state driving half bridge 7 is used to apply the voltage (6V) of the on-state driving power supply 6 to the gate voltage V of the GaN HEMT device 9 to be driven. GS , so that the GaN HEMT device 9 to be driven is in the on state; Figure 5 As shown in FIG. 1 , a switching waveform diagram of a single phase shift control DAB circuit of an embodiment of a GaN HEMT device three-state driving circuit of the present invention is shown in FIG. Figure 1 It can be seen that by adopting the GaN HEMT three-state driving circuit of the present invention, the switch tube Q in the DAB circuit can be H1 , Q H4After the shutdown, the switch is in the freewheeling driving state in the dead time t3-t4 to maintain a low reverse voltage drop and reduce losses, and maintains the normal shutdown state in the other dead time t0-t1 and t6-t7; H2 , Q H3 After the shutdown, the switch is in the freewheeling driving state during the dead time t0-t1 and t6-t7, and remains in the normal off state during the other dead time t3-t4. Therefore, the reverse tube voltage drop V of the switch tube in the freewheeling driving state can be reduced. SD , in order to reduce the follow-on loss and improve the device efficiency. Figure 2 The typical switching waveform of the prior art dual active bridge (DAB) topology using single phase shift control is shown in FIG. Figure 5 and Figure 2 By comparison, it can be seen that the GaN HEMT three-state driving circuit of the present invention has no influence on the operation mode of the circuit.

[0053] In addition, the freewheeling drive anti-reverse diode 8 has an anode connected to the source of the freewheeling drive switch tube 5 and a cathode connected to the gate of the GaN HEMT device 9 to be driven (this point is also connected to the midpoint of the conduction drive half-bridge 7), that is, it is connected in series between the freewheeling drive switch tube 5 and the midpoint of the conduction drive half-bridge 7. When the GaN HEMT device 9 to be driven is in the on state, the voltage of the conduction drive power supply 6 is prevented from being applied to the freewheeling drive power supply 4, causing a short circuit.

[0054] It should be noted that the GaN HEMT three-state driving circuit proposed in the present invention is not limited to being constructed using discrete devices, and an integrated driving chip can also be used to implement the three-state driving method proposed in the present invention, which is not described in detail in the present invention.

[0055] It should be noted that the GaN HEMT device tri-state driving circuit provided in the above embodiment is only illustrated by the division of the above functional modules. In practical applications, the above functions can be assigned to different functional modules as needed, that is, the modules in the embodiment of the present invention can be decomposed or combined. For example, the modules in the above embodiment can be combined into one module, or further divided into multiple sub-modules to complete all or part of the functions described above. The names of the modules involved in the embodiments of the present invention are only for distinguishing the modules and are not regarded as improper limitations of the present invention.

[0056] The terms "first", "second", etc. are used to distinguish similar objects rather than to describe or indicate a particular order or sequence.

[0057] The term "comprise" or any other similar term is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus / device that includes a list of elements includes not only those elements but also other elements not expressly listed, or also includes elements inherent to such process, method, article, or apparatus / device.

[0058] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A GaN HEMT device tri-state driving circuit, characterized in that: The GaN HEMT device tri-state drive circuit includes an input end of a PWM1 drive signal, an input end of a PWM2 drive signal, an SR latch, a freewheeling drive switch tube, a freewheeling drive power supply, a conduction drive half bridge, a conduction drive power supply and a freewheeling drive anti-reverse diode; The set end of the SR latch is connected to the input end of the PWM1 drive signal, the reset end is connected to the input end of the PWM2 drive signal, and the output end is connected to the gate of the freewheeling drive switch tube; The drain of the freewheeling drive switch tube is connected to the positive electrode of the freewheeling drive power supply, and the source is connected to the gate of the GaN HEMT device to be driven through the freewheeling drive anti-reverse diode; The conduction drive half bridge includes an upper tube and a lower tube, the gate of the upper tube is connected to the input end of the PWM1 drive signal, the drain is connected to the positive electrode of the conduction drive power supply, the gate of the lower tube is connected to the input end of the PWM2 drive signal, and the source of the upper tube and the drain of the lower tube are connected together to the gate of the GaN HEMT device to be driven; The negative electrode of the freewheeling driving power supply, the negative electrode of the conduction driving power supply and the source electrode of the lower tube are all grounded.

2. The GaN HEMT device tri-state driving circuit according to claim 1, characterized in that: The PWM1 driving signal and the PWM2 driving signal both have a dead time, and the signals outside the dead time are complementary.

3. The GaN HEMT device tri-state driving circuit according to claim 2, characterized in that: The SR latch drives the freewheeling drive switch tube to turn on during the dead time after the GaN HEMT device to be driven is turned off, and keeps the freewheeling drive switch tube turned off during the dead time before the GaN HEMT device to be driven is turned on.

4. The GaN HEMT device tri-state driving circuit according to claim 1, characterized in that: The timing signal between the PWM1 driving signal, the PWM2 driving signal and the SR latch is used to control the GaN HEMT device to be driven to be in an off state, an on state or a freewheeling state.

5. The GaN HEMT device tri-state driving circuit according to claim 1, characterized in that: The on-driving half-bridge is used to drive the GaN HEMT device to be driven under the timing signal between the PWM1 driving signal, the PWM2 driving signal and the SR latch, so that the GaN HEMT device to be driven is in an on state or an off state; The freewheeling driving switch tube is used to drive the GaN HEMT device to be driven under the timing signal between the PWM1 driving signal, the PWM2 driving signal and the SR latch, so that the GaN HEMT device to be driven is in a freewheeling state.

6. The GaN HEMT device tri-state driving circuit according to claim 5, characterized in that: The freewheeling drive switch tube is turned on in the freewheeling stage after the GaN HEMT device to be driven is turned off, and is used to apply the voltage of the freewheeling drive power supply to the gate of the GaN HEMT device to be driven, so that the GaN HEMT device to be driven remains turned off in the freewheeling state, and the reverse conduction voltage drop of the GaN HEMT device to be driven is reduced.

7. The GaN HEMT device tri-state driving circuit according to claim 6, characterized in that: The voltage of the freewheeling driving power supply is less than the gate turn-on voltage of the GaN HEMT device to be driven.

8. The GaN HEMT device tri-state driving circuit according to claim 1, characterized in that: The conduction driving half-bridge is used to apply the voltage of the conduction driving power supply to the gate of the GaN HEMT device to be driven, so that the GaN HEMT device to be driven is in a conduction state.

9. The GaN HEMT device tri-state driving circuit according to claim 1, characterized in that: The freewheeling drive anti-reverse diode has an anode connected to the source of the freewheeling drive switch tube, and a cathode connected to the gate of the GaN HEMT device to be driven.

10. The GaN HEMT device tri-state driving circuit according to claim 9, characterized in that: The freewheeling drive anti-reverse diode is used to prevent a short circuit caused by the voltage of the on-state drive power supply being applied to the freewheeling drive power supply when the GaN HEMT device to be driven is in the on-state.

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