Novel gallium nitride half-bridge drive circuit

Abstract

The invention discloses a novel gallium nitride half-bridge drive circuit which comprises an LLC control unit which is suitable for the application that silicon MOS transistors in all half-bridge topology LLC resonant circuits are upgraded into gallium nitride. An LLC resonant controller chip U7 is adopted for generating a half-bridge driving signal, and positive and negative voltages and high-speed driving necessary for a gallium nitride power tube are generated through a unit control circuit, so that high-frequency and high-efficiency control and soft switching functions of the power supply resonant converter are realized; and the dual-power supply module comprises LDO voltage stabilizers U5, U9, R50, R71, D14, D17, C31, C35, C40 and C45 and is used for generating stable positive voltage and negative voltage from a main power supply and independently supplying power to a high-side driving circuit and a low-side driving circuit, and the defect that the charging response speed of a traditional bootstrap capacitor is low is overcome. According to the scheme, an independent power supply is used for replacement, faster response and higher driving capacity are provided, reliable turn-off of the GaN tube is ensured through positive and negative voltages, the output power of gallium nitride can be greatly improved, efficiency is improved, and therefore electromagnetic interference (EMI) and thermal stress are reduced.

Description

Technical Field

[0001] This invention relates to the field of gallium nitride half-bridge driving technology, specifically a novel gallium nitride half-bridge driving circuit. Background Technology

[0002] Traditional LLC converter chips are primarily designed to drive silicon-based MOSFETs, with a drive voltage range of 10-15V. When used with GaN power transistors, these chips need to adapt to the positive and negative voltage drive requirements of GaN. Currently, the mainstream solution uses a resistor-capacitor (RC) step-down circuit (i.e., using resistors and capacitors to achieve voltage reduction and division), but this has significant drawbacks:

[0003] Power limitations: The power output of RC circuits is limited by the voltage withstand capability and heat dissipation of the components, and cannot support high-power applications (e.g., hundreds of watts or more).

[0004] Low efficiency: RC step-down introduces additional losses (such as resistor heat dissipation), leading to a decrease in overall system efficiency, especially in high-frequency switching scenarios.

[0005] Stability issues: Traditional methods relying on bootstrap capacitors have slow response speeds and are prone to voltage instability, affecting the switching performance of GaN transistors and system reliability.

[0006] This invention addresses these pain points by providing a driving scheme that directly generates positive and negative voltages from the power supply terminal, avoiding the limitations of voltage generation at the signal terminal, thereby achieving high-power, high-efficiency GaN direct drive. Summary of the Invention

[0007] The purpose of this invention is to provide a novel gallium nitride half-bridge driver circuit to solve the problems mentioned in the background art.

[0008] To achieve the above objectives, the present invention provides the following technical solution: a novel gallium nitride half-bridge driving circuit, comprising:

[0009] The LLC control unit uses the LLC resonant controller chip U7 to generate half-bridge drive signals, control the switching frequency and dead time of the high-side and low-side GaN power transistors, and realize the frequency modulation control and soft-switching function of the resonant converter.

[0010] The dual power supply module, including LDO regulator U5 and LDO regulator U9, is used to generate stable positive and negative voltages to provide stable power to the high-side and low-side gallium nitride, avoiding the voltage mismatch problem of traditional LLC chip driving gallium nitride.

[0011] The GaN power half-bridge module includes a high-side GaN power transistor Q5 and a low-side GaN power transistor Q8, which are connected to form a half-bridge structure. The output terminal is connected to a resonant network to achieve high power output.

[0012] The positive and negative voltage drive module, including the high-side drive chip U6 and the low-side drive chip U10, is used to improve the frequency response speed and drive capability, directly drive the GaN power transistors Q5 and Q8, ensure reliable switching and prevent false turn-on.

[0013] Preferably, pin 3 of the LDO regulator U5 is connected to pin 16 of the chip U7, and pin 3 of the LDO regulator U5 is also connected to one end of capacitor C34. The other end of capacitor C34 and pin 2 of the LDO regulator U5 are both grounded.

[0014] Preferably, pin 1 of the LDO regulator U5 is connected to one end of capacitor C33, one end of resistor R50, and one end of capacitor C31, and is connected to pin 1 of the high-side driver chip U6. The other end of resistor R50 is connected to one end of diode D14, and the other end of capacitor C31 is connected to one end of capacitor C35. The other ends of capacitor C33, diode D14, and capacitor C35 are grounded.

[0015] Preferably: pin 2 of the high-side driving chip U6 is grounded; pin 3 of the high-side driving chip U6 is connected to one end of resistor R49 and one end of resistor R51; the other end of resistor R49 is connected to pin 15 of chip U7; the other end of resistor R51 and pin 4 of the high-side driving chip U6 are grounded; pin 5 of the high-side driving chip U6 is connected to one end of resistor R42 and one end of diode D12; the other end of resistor R42 and the other end of diode D12 are connected to the gate of the high-side GaN power transistor Q5; the gate of the high-side GaN power transistor Q5 is also connected to one end of resistor R46; the other end of resistor R46 is grounded; and the source of the high-side GaN power transistor Q5 is connected to the drain of the low-side GaN power transistor Q8.

[0016] Preferably, pin 3 of the LDO regulator U9 is connected to pin 12 of the chip U7, and pin 3 of the LDO regulator U9 is also connected to one end of capacitor C43. The other end of capacitor C43, pin 10 of chip U7, and pin 2 of LDO regulator U9 are all grounded.

[0017] Preferably, pin 1 of the LDO regulator U9 is connected to one end of capacitor C42, one end of resistor R71, and one end of capacitor C40, and is connected to pin 1 of the low-side driver chip U10. The other end of resistor R71 is connected to one end of diode D17, and the other end of capacitor C40 is connected to one end of capacitor C45. The other ends of capacitor C42, diode D17, and capacitor C45 are grounded.

[0018] Preferably: pin 2 of the low-side driving chip U10 is grounded; pin 3 of the low-side driving chip U10 is connected to one end of resistor R68 and one end of resistor R70; the other end of resistor R68 is connected to pin 11 of chip U7; the other end of resistor R70 and pin 4 of the low-side driving chip U10 are grounded; pin 5 of the low-side driving chip U10 is connected to one end of resistor R58 and one end of diode D15; the other end of resistor R58 and the other end of diode D15 are connected to the gate of the low-side GaN power transistor Q8; the gate of the low-side GaN power transistor Q8 is also connected to one end of resistor R69; the other end of resistor R69 is grounded.

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

[0020] 1. Eliminate the defects of bootstrap capacitors: Traditional bootstrap capacitors charge slowly and are prone to leakage. This solution replaces them with an independent power supply, providing faster response and higher duty cycle support.

[0021] 2. Stable drive: Positive and negative voltages ensure reliable turn-off of GaN transistors, reducing electromagnetic interference (EMI) and thermal stress.

[0022] 3. High power and stability: The output power can be greatly increased and the efficiency can be improved, making it suitable for high-power applications such as electric vehicle charging and photovoltaic inverters.

[0023] 4. Reduce system costs, improve reliability, and have quantification potential. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the present invention;

[0025] Figure 2 This is the circuit diagram of the present invention. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0027] Please see Figure 1-2 This invention provides a technical solution: a novel gallium nitride half-bridge driving circuit, comprising:

[0028] LLC control module: It adopts LLC resonant controller chip U7 to generate half-bridge drive signals, control the switching frequency and dead time of the high-side and low-side GaN power transistors, and realize the frequency modulation control and soft switching function of the resonant converter.

[0029] Dual power supply module: Includes independent positive power supply (VDD, Vcc) and negative power supply generation circuits, as well as LDO regulator U5, LDO regulator U9, capacitor C33 and capacitor C42, used to generate stable positive and negative voltages to stably power the high-side and low-side gallium nitride, avoiding the voltage mismatch problem of traditional LLC chip driving gallium nitride.

[0030] Positive and negative voltage drive module: including resistor R50, resistor R71, diode D14, diode D17, capacitor C31, capacitor C35, capacitor C40, and capacitor C45, used to generate stable positive and negative voltages. High-side drive chip U6 and low-side drive chip U10 are used to improve frequency response speed and drive capability, directly drive GaN power transistors Q5 and Q8, ensure reliable switching and prevent false turn-on.

[0031] GaN power half-bridge module: It includes a high-side GaN power transistor Q5 (M-upper) and a low-side GaN power transistor Q8 (M-lower), which are connected to form a half-bridge structure. The output is connected to the HB (midpoint of the half-bridge) and BO nodes, and then connected to the resonant network to achieve high power output.

[0032] Grounding and isolation module: Includes independent grounding such as PGND, 13VHGND, and 13VGND to ensure isolation between high-side and low-side drives and reduce noise coupling.

[0033] Diodes D12 and D15 are used for clamping and protection, capacitors C29, C34, C43, and C47 are used for filtering and decoupling, and resistors R42, R46, R49, R51, R58, R68, R69, and R70 are used for current limiting and voltage division to ensure circuit stability and anti-interference capability.

[0034] Working principle: In the LLC control module, the controller chip U7 has the following pins: Css (1), Fmax (2), Ctimer (3), Rt (4), HB (14), BO (5), FB (6), DT (7), Skip / Disable (8), Fault (9), GND (10), Vcc (12), VL (13), etc. U7 generates a high-side drive signal PHOa and a low-side drive signal PLOa, which are output to the driver stage through the HB and BO pins to realize frequency control and dead-time adjustment, ensuring ZVS soft switching.

[0035] In the dual power supply module, VDD and Vcc provide the main positive power supply. U5 (LDO, pins in(3), GND(2), out(1)) and U9 (similar to LDO) regulate the voltage to generate high-side 8VH and low-side 8VL voltages respectively. Diodes such as D15 and D17 prevent reverse current, capacitors such as C34, C40, C42, and C45 filter high-frequency noise, and R68, R70, and R71 limit current to ensure stable and independent supply of positive and negative voltages, unaffected by the signal terminals.

[0036] In the positive and negative voltage drive module and the GaN power half-bridge module, the high-side drive U6 (pins VDD(1), GND(2), IN+(3), IN-(4), OUT(5)) receives the PHOa signal and outputs it to the gate of Q5, providing positive and negative drive voltages through 13VH and 13VHGND; the low-side drive U10 is similar, receiving PLOa and driving Q8. R49 and R51 divide the voltage to adjust the gate voltage, R42 and R58 limit the current to protect the gate, D12 and D14 clamp the voltage spike, and C31, C33, and C35 decouple to ensure fast response and reliable turn-off of the GaN tube. The midpoint HB of the half-bridge is connected to the resonant network to realize high-power direct drive output.

[0037] Process: The input power supply generates independent positive and negative voltages via a dual power supply module. LDOs (U5, U9, etc.) regulate the voltage and supply it to the driver chips (U6, U10). The drive signals (PHOa, PLOa) drive the GaN transistors (Q5, Q8) through the high-side (Mupper) and low-side (Mlower) signals. The half-bridge outputs (HB, BO) are connected to an LLC resonant network to achieve power conversion.

[0038] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A novel gallium nitride half-bridge driver circuit, characterized in that, include: The LLC control unit uses the LLC resonant controller chip U7 to generate half-bridge drive signals, control the switching frequency and dead time of the high-side and low-side GaN power transistors, and realize the frequency modulation control and soft-switching function of the resonant converter. The dual power supply module, including LDO regulator U5 and LDO regulator U9, is used to generate stable positive and negative voltages to provide stable power to the high-side and low-side gallium nitride, avoiding the voltage mismatch problem of traditional LLC chip driving gallium nitride. The GaN power half-bridge module includes a high-side GaN power transistor Q5 and a low-side GaN power transistor Q8, which are connected to form a half-bridge structure. The output terminal is connected to a resonant network to achieve high power output. The positive and negative voltage drive module, including the high-side drive chip U6 and the low-side drive chip U10, is used to improve the frequency response speed and drive capability, directly drive the GaN power transistors Q5 and Q8, ensure reliable switching and prevent false turn-on.

2. The novel gallium nitride half-bridge driving circuit according to claim 1, characterized in that: Pin 3 of the LDO regulator U5 is connected to pin 16 of the chip U7. Pin 3 of the LDO regulator U5 is also connected to one end of capacitor C34. The other end of capacitor C34 and pin 2 of the LDO regulator U5 are both grounded.

3. The novel gallium nitride half-bridge driving circuit according to claim 2, characterized in that: Pin 1 of the LDO regulator U5 is connected to one end of capacitor C33, one end of resistor R50, and one end of capacitor C31, and is connected to pin 1 of the high-side driver chip U6. The other end of resistor R50 is connected to one end of diode D14, and the other end of capacitor C31 is connected to one end of capacitor C35. The other ends of capacitor C33, diode D14, and capacitor C35 are grounded.

4. The novel gallium nitride half-bridge driving circuit according to claim 3, characterized in that: Pin 2 of the high-side driver chip U6 is grounded. Pin 3 of the high-side driver chip U6 is connected to one end of resistor R49 and one end of resistor R51. The other end of resistor R49 is connected to pin 15 of chip U7. The other end of resistor R51 and pin 4 of the high-side driver chip U6 are grounded. Pin 5 of the high-side driver chip U6 is connected to one end of resistor R42 and one end of diode D12. The other end of resistor R42 and the other end of diode D12 are connected to the gate of the high-side GaN power transistor Q5. The gate of the high-side GaN power transistor Q5 is also connected to one end of resistor R46. The other end of resistor R46 is grounded. The source of the high-side GaN power transistor Q5 is connected to the drain of the low-side GaN power transistor Q8.

5. A novel gallium nitride half-bridge driver circuit according to claim 1, characterized in that: Pin 3 of the LDO regulator U9 is connected to pin 12 of the chip U7. Pin 3 of the LDO regulator U9 is also connected to one end of the capacitor C43. The other end of the capacitor C43, pin 10 of the chip U7, and pin 2 of the LDO regulator U9 are all grounded.

6. A novel gallium nitride half-bridge driving circuit according to claim 5, characterized in that: Pin 1 of the LDO regulator U9 is connected to one end of capacitor C42, one end of resistor R71, and one end of capacitor C40, and is connected to pin 1 of the low-side driver chip U10. The other end of resistor R71 is connected to one end of diode D17, and the other end of capacitor C40 is connected to one end of capacitor C45. The other ends of capacitor C42, diode D17, and capacitor C45 are grounded.

7. A novel gallium nitride half-bridge driving circuit according to claim 6, characterized in that: Pin 2 of the low-side driver chip U10 is grounded. Pin 3 of the low-side driver chip U10 is connected to one end of resistor R68 and one end of resistor R70. The other end of resistor R68 is connected to pin 11 of chip U7. The other end of resistor R70 and pin 4 of the low-side driver chip U10 are grounded. Pin 5 of the low-side driver chip U10 is connected to one end of resistor R58 and one end of diode D15. The other end of resistor R58 and the other end of diode D15 are connected to the gate of the low-side GaN power transistor Q8. The gate of the low-side GaN power transistor Q8 is also connected to one end of resistor R69. The other end of resistor R69 is grounded.

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