GaN device bridge arm isolation driving circuit
By designing the bridge arm isolation driving circuit of GaN device and using transformers to isolate and convert the driving signal, the problems of driving voltage oscillation and multi-isolated power supply in bridge applications of GaN devices are solved, achieving high-frequency reliable driving and cost reduction.
Patent Information
- Application Number
- CN202510384656.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-28
- Publication Date
- 2025-07-11
AI Technical Summary
In the prior art, GaN devices have a small safety margin for driving voltage in bridge applications, which can easily cause driving voltage oscillation, resulting in bomb failure, and require multiple independent isolated power supplies to increase the system volume, weight and cost.
A GaN device bridge arm isolation driving circuit is designed, using two isolated driving circuits and one full-bridge power circuit, and isolate and transform the driving signals through a transformer to realize the isolated driving of the GaN device, and ensure the driving level without using an independent isolated power supply, and share the control circuit power supply.
It realizes reducing costs without increasing the system volume and weight, providing reliable GaN device driving, frequency not less than 1MHz, and sharing control circuit power supply, reducing control circuit power consumption.
Smart Images
Figure CN120301165A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of overall aerospace technology, and particularly to a bridge arm isolation drive circuit for GaN devices. Background Art
[0002] With the rapid development of aerospace technology, the power capacity of spacecraft power systems has been continuously increasing, and the requirements for the performance and reliability of electronic devices have become increasingly stringent. The third-generation semiconductor material GaN has broad prospects in high-frequency, high-voltage, high-temperature, and high-power application scenarios. However, its gate drive voltage ranges from -5V to +6V, and the drive safety margin is very small. The drive voltage oscillation caused by parasitic parameters in the drive loop during high-frequency operation is likely to cause a breakdown fault. In bridge applications, there are currently very few space-qualified chips available, and an isolated drive power supply needs to be configured separately. In multi-bridge arm application scenarios, a large number of isolated drive power supplies are required, which has many negative effects on the volume, weight, and cost of the system. Summary of the Invention
[0003] The technical problem solved by the present invention is to overcome the deficiencies of the prior art and provide a bridge arm isolation drive circuit for GaN devices. Without using an independent isolated power supply, it can not only ensure the drive level required by GaN but also make the drive signal source and the control circuit share the same ground, reducing the volume, weight, and cost of the system.
[0004] The technical solution of the present invention is: a bridge arm isolation drive circuit for GaN devices, including two isolation drive circuits and a full-bridge power circuit. The two isolation drive circuits have the same structure and a phase difference of 180°. One isolation drive circuit isolates and transforms the drive signal through a transformer to drive two GaN devices in the full-bridge power circuit. The transformer has a total of four windings, namely a primary winding, a reset winding, a secondary winding I, and a secondary winding II.
[0005] At the primary end of the transformer, the PWM signal is connected to the base of the triode Q1 through the resistor R1, and the diode D2 is connected in parallel with the resistor R1, and the cathode is connected to the PWM signal. The emitter of the triode Q1 is connected to the control return line, and the collector is connected to the non-homonymous end of the primary winding, which is used to amplify the PWM signal and provide a square wave input to the transformer through conduction and cut-off. The homonymous end of the primary winding and the non-homonymous end of the reset winding are connected in parallel and then connected to the control power supply VCC. The homonymous end of the reset winding is connected to the cathode of the diode D1, and the anode of the diode D1 is connected to the control return line to reset the transformer.
[0006] The secondary side of the transformer outputs an isolated drive signal, which drives 1 GAN device through the secondary winding I and the secondary winding II respectively. The connection circuit structure between each secondary winding and the GAN device it drives is the same, which is: the same-name ends of the secondary winding are sequentially connected to the gate of the GAN device through the resistor R2, the DC-blocking capacitor C2, and the resistor R4. The non-same-name end is connected to the cathode of the rectifier diode D4, and the anode of the diode D4 is connected to the emitter of the triode Q2 and then connected to the source of the GAN device; the base of the triode Q2 is connected to the anode of the diode D3, the cathode of the diode D3 is connected to the non-same-name end of the secondary winding, and a resistor R3 is connected in parallel across both ends of the diode D3. The collector of the triode Q2 is connected to the connection point of the resistor R2 and the capacitor C2; the anodes of the voltage regulator diode Z1 and the voltage regulator diode Z2 are connected together. The cathode of the voltage regulator diode Z1 is connected to the connection point of the DC-blocking capacitor C2 and the drive resistor R4, and the cathode of the voltage regulator diode Z2 is connected to the emitter of the triode Q2 to protect the gate of the GAN device; the two ends of the resistor R8 are respectively connected to the cathode of the voltage regulator diode Z1 and the cathode of the voltage regulator diode Z2 to discharge the gate capacitance of the GAN device.
[0007] Furthermore, the PWM signal from the control circuit drives the conduction and cutoff of the triode Q1;
[0008] When the triode Q1 conducts, the control power supply is applied to the primary winding of the transformer, and the secondary side of the transformer starts to transfer energy. The secondary winding charges the gate capacitance of the GaN device, realizing the turn-on of the GaN device. The diode D4 conducts, accelerating the cutoff of the turn-off triode Q2. The voltage of the DC-blocking capacitor C2 gradually rises until it is fully charged during the conduction of Q1, and the gate voltage of the GaN device gradually decreases, and the decreased amplitude is equal to the charging voltage of C2;
[0009] When the triode Q1 turns off, the diode D4 turns off, the transformer stops transferring energy, accelerating the conduction of the triode Q2. The DC-blocking capacitor C2 is equivalent to a voltage source, and the stored energy is reversely charged to the gate capacitance of the GaN device through the triode Q2, accelerating the turn-off of the GaN device. The energy stored in the transformer is reset through the reset winding, and the energy is fed back to the control power supply.
[0010] Furthermore, by changing the turns ratio setting of the transformer and changing the capacitance of the DC-blocking capacitor, the required drive voltage amplitude of the GaN device can be obtained.
[0011] Furthermore, the control power supply VCC and the control return line are connected through the capacitor C1 for filtering to smooth the auxiliary supply voltage.
[0012] Furthermore, the voltage regulator diode Z1 conducts when the drive voltage or the glitch ringing is higher than the required value of the GaN device gate, preventing the GaN device gate from being broken down.
[0013] Further, the resistor R1 and the resistor R3 control the turn-on speed of the triode Q1 and the triode Q2; the diode D2 and the diode D3 accelerate the turn-off speed of the triode Q1 and the triode Q2.
[0014] Further, the full-bridge power circuit includes GaN devices M1 to M4. M1 and M2 form a bridge arm, and M4 and M3 form a bridge arm; one path of isolated drive circuit is used to drive M1 and M3, and the other path of isolated drive circuit is used to drive M2 and M4.
[0015] The present invention also provides a spacecraft power system, including the GaN device bridge arm isolated drive circuit as described above.
[0016] The present invention also provides a ground electronic device, including the GaN device bridge arm isolated drive circuit as described above.
[0017] The advantages of the present invention compared with the prior art are as follows:
[0018] (1) The present invention is applicable to bridge circuits. Without using an independent isolated power supply, it can realize the isolated drive of multi-bridge arm GaN devices, and can achieve a gate drive voltage of -5 to +6V and a frequency not lower than 1MHz. It effectively reduces the system volume, weight and cost, while ensuring the reliability requirements.
[0019] (2) The isolated drive circuit of the present invention adopts a current control method, which has faster turn-on and turn-off speeds than the traditional voltage control circuit, has lower requirements for the PWM output by the control circuit, can reduce the power consumption of the control circuit, and the drive amplitude is greater than 2V and the drive capacity is greater than 2mA, then it can realize the reliable drive of GaN devices.
[0020] (3) The isolated drive circuit of the present invention can share the power supply of the original control circuit, without the need to independently design or select a drive power supply, which can reduce the cost. At the same time, by reasonably setting the number of turns and turn ratio of the transformer, the required drive level can be accurately obtained. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 It is a schematic diagram of the isolated drive circuit of the present invention. DETAILED DESCRIPTION OF THE INVENTION
[0022] In order to better understand the technical solution of the present invention, the specific embodiments of the present invention will be specifically described below with reference to the drawings.
[0023] As Figure 1 shown, it is a schematic diagram of the isolated drive circuit of the present invention, including an isolated drive circuit 1 and a full-bridge power circuit 2; by using a single stable control power supply to isolate and transform the drive signal through a transformer to drive multi-bridge arms, the system complexity can be greatly reduced and the power density can be improved.
[0024] The full-bridge power circuit 2 includes GaN power devices M1 - M4.
[0025] M1 and M2 form one arm, M4 and M3 form one arm. The drains D of M1 and M4 are connected and then connected to the positive power bus. The source S of M1 is connected to the drain D of M2. At the same time, the source of M1 is connected to the cathode of the voltage regulator diode Z2 in the drive circuit 1. The sources S of M2 and M3 are connected and then connected to the power bus return line. At the same time, the source of M3 is connected to the cathode of the voltage regulator diode Z4 in the drive circuit 1. The source S of M4 and the gate of M3 are connected to the cathode of the voltage regulator diode Z4 in the drive circuit 1.
[0026] For a complete full-bridge circuit, there are a total of 4 GaN power devices. Figure 1 The isolation drive circuit 1 shown drives two diagonal GaN power devices, namely M1 and M3. A complete full-bridge circuit requires 2 isolation drive circuits, but the working mechanism of each isolation drive circuit is exactly the same, only the phase difference is 180°. Therefore, the working principle of one isolation drive circuit is described as an example here.
[0027] The isolation drive circuit includes: resistors R1 - R9, capacitors C1 - C3, voltage regulator diodes Z1 - Z4, diodes D1 - D6, transistors Q1 - Q3, and isolation transformer T1.
[0028] The transformer T1 has a total of 4 windings, namely 1 - 2, 3 - 4, 5 - 6, 7 - 8. The odd-numbered pins are the same-name terminals, that is, 1, 3, 5, and 7 are the same-name terminals.
[0029] The primary side of the transformer: The control signal PWM1 from the control chip is connected to one end of the resistor R1. The other end of the resistor R1 is connected to the base of the transistor Q1. The diode D2 is in parallel with R1, and the cathode is also connected to the PWM1 signal. The resistor R1 is used for current limiting and eliminating ringing. The diode D2 is used for accelerating turn-off. The emitter of the transistor Q1 is connected to the control return line, and the collector is connected to the 2-pin of the transformer T1. The transistor Q1 is used to amplify the PWM1 signal and at the same time provide a square-wave input for the transformer T1 through conduction and turn-off. The 1-pin and 8-pin of the transformer T1 are connected in parallel and then connected to the control power supply VCC. VCC is connected to one end of the capacitor C1 for filtering. The other end of the capacitor C1 is connected to the control return line. The 7-pin of the transformer is connected to the cathode of the diode D1, and the anode of the diode D1 is connected to the control return line, which is used to reset the transformer.
[0030] The secondary side of the transformer: Outputs the isolated drive signal. The two secondary windings 3 - 4 and 5 - 6 respectively drive 2 GAN power devices.
[0031] The connection relationship of the secondary side 3-4 winding is as follows: Pin 3 of transformer T1 is connected to one end of R2 of the driving resistor, the other end of R2 is connected to one end of the DC-blocking capacitor C2, the other end of C2 is connected to one end of the driving resistor R4, the other end of R4 is directly connected to the gate of the GAN power device M1, pin 4 of transformer T1 is connected to the cathode of the rectifier diode D4, the anode of D4 is connected to the emitter of the turn-off triode Q2 and then connected to the source S of the GAN power device M1. The resistor R3 is connected in parallel with the diode D3, the parallel connection end with the cathode of D3 is connected to pin 4 of transformer T1, and the other end is connected to the base of Q2. The collector of Q2 is connected to the connection point of the resistor R2 and the capacitor C2; the anodes of the voltage-regulator diodes Z1 and Z2 are connected together, the cathode of Z1 is connected to the connection point of the capacitor C2 and R4, the cathode of Z2 is connected to the emitter of the triode Q2, which is used to protect the gate of the GAN power device M1. The cathodes of Z1 and Z2 are respectively connected to both ends of the resistor R8, which is used to discharge the gate junction capacitance of M1.
[0032] The connection relationship of the secondary side 5-6 winding is as follows: Pin 5 of transformer T1 is connected to one end of R5 of the driving resistor, the other end of R5 is connected to one end of the DC-blocking capacitor C3, the other end of C3 is connected to one end of the driving resistor R7, the other end of R7 is directly connected to the gate of the GAN power device M3, pin 6 of transformer T1 is connected to the cathode of the rectifier diode D6, the anode of D6 is connected to the emitter of the turn-off triode Q3 and then connected to the source S of the GAN power device M3. The resistor R6 is connected in parallel with the diode D5, the parallel connection end with the cathode of D5 is connected to pin 6 of transformer T1, and the other end is connected to the base of Q3. The collector of Q3 is connected to the connection point of the resistor R5 and the capacitor C3; the anodes of the voltage-regulator diodes Z3 and Z4 are connected together, the cathode of Z3 is connected to the connection point of the capacitor C3 and R7, the cathode of Z4 is connected to the emitter of the triode Q3, which is used to protect the gate of the GAN power device M3. The cathodes of Z3 and Z4 are respectively connected to both ends of the resistor R9, which is used to discharge the gate junction capacitance of M3.
[0033] During the operation of the circuit, the PWM signal PWM1 from the control circuit drives the conduction and turn-off of the triode Q1. Since Q1 is a current-controlled device, it can achieve extremely high turn-on and turn-off speeds.
[0034] When Q1 conducts, the control power supply is applied to the primary 1-2 winding of transformer T1, and the secondary side of the transformer works to transfer energy outward. The secondary windings 3-4 and 5-6 respectively charge the gate capacitors of power GaN devices M1 and M3 to turn on the power GaN devices. At this time, diodes D4 and D6 conduct, accelerating the turn-off of transistors Q2 and Q3 to cut off. C2 and C3 are charged as DC-blocking capacitors until they are full. During the conduction process of Q1, the voltage gradually rises, and the gate voltages of M1 and M3 gradually decrease. The decreased amplitude is equal to the charging voltage of C2 and C3. By reasonably setting the turns ratio of the primary and secondary sides of the transformer, the amplitude of the required transformer output pulse can be achieved. By reasonably selecting the capacitance of DC-blocking capacitors C2 and C3, the DC-blocking voltage can be set, that is, the required driving pulse amplitude can be obtained. Zener diode Z1 conducts when the driving voltage or glitch ringing is higher than the gate requirement value of the GaN device to prevent the gate of the GaN device from being broken down.
[0035] When Q1 turns off, diodes D4 and D6 cut off, the transformer stops transferring energy, accelerating the turn-on of transistors Q2 and Q3. The DC-blocking capacitors C2 and C3 are equivalent voltage sources, and the stored energy reversely charges the gate capacitors of M1 and M3 through Q2 and Q3 to accelerate the turn-off of M1 and M3. At the same time, discharge resistors R8 and R9 can also play a role in accelerating the turn-off. At this time, the energy stored in the transformer is reset through the auxiliary winding 7-8, and the energy is fed back to the control power supply.
[0036] During actual use, VCC can be the same as the auxiliary power supply of the control circuit, but it is necessary to ensure the stability of VCC. Then, according to the amplitude of VCC and the voltage required by the gate of the GaN power device, the turns ratio is determined. The output voltage Vo of the secondary side of the transformer is equal to the sum of the diode conduction voltage drop VD and the DC-blocking capacitor voltage VC. To improve the accuracy of gate voltage regulation, the number of turns of the primary and secondary sides of the transformer can be increased as much as possible to make the voltage per turn as low as possible.
[0037] Resistors R2 and R4 are the driving turn-on resistors of M1, and resistors R5 and R7 are the driving turn-on resistors of M3, which can control the rising slope of the driving waveform. While R4 and R7 are used as turn-off resistors to control the falling slope of the driving waveform during the turn-off process. Resistors R8 and R9 slowly discharge the gate capacitors.
[0038] Resistors R1, R3, and R6 can control the turn-on speed of transistors Q1-Q3, and diodes D2, D3, and D5 can accelerate the turn-off speed of transistors Q1-Q3.
[0039] Zener diodes Z1 and Z3 determine the amplitude of the forward protection voltage, and Z2 and Z4 determine the amplitude of the negative protection voltage. Under normal conditions, the zener diodes do not work, and only when there are spikes and ringing in the loop, the zener diodes conduct to complete the protection.
[0040] It should be understood that the present invention is described by way of examples. Those skilled in the art will appreciate that various changes or equivalent substitutions can be made to these features and examples without departing from the spirit and scope of the present invention. Additionally, under the teachings of the present invention, these features and examples can be modified to suit specific circumstances without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and embodiments that fall within the scope of the claims of this application all belong to the scope protected by the present invention.
[0041] Contents not detailedly described in the specification of the present invention are well-known technologies to those skilled in the art.
Claims
1. A GaN device bridge arm isolation drive circuit, characterized in that: It includes two isolated drive circuits and one full-bridge power circuit. The two isolated drive circuits have the same structure and a phase difference of 180°. One isolated drive circuit isolates and transforms the drive signal through a transformer to drive two GaN devices in the full-bridge power circuit. The transformer has a total of four windings, namely the primary winding, the reset winding, the secondary winding I, and the secondary winding II. At the primary end of the transformer, the PWM signal is connected to the base of the triode Q1 through the resistor R1. The diode D2 is connected in parallel with the resistor R1, and the cathode is connected to the PWM signal. The emitter of the triode Q1 is connected to the control return line, and the collector is connected to the non-homonymous end of the primary winding, which is used to amplify the PWM signal and provide a square-wave input to the transformer through conduction and cutoff. The homonymous end of the primary winding and the non-homonymous end of the reset winding are connected in parallel and then connected to the control power supply VCC. The homonymous end of the reset winding is connected to the cathode of the diode D1, and the anode of the diode D1 is connected to the control return line to reset the transformer. At the secondary end of the transformer, the isolated drive signal is output. Each of the secondary winding I and the secondary winding II drives one GAN device. The connection circuit structure between each secondary winding and the GAN device it drives is the same, which is: the homonymous end of the secondary winding is sequentially connected to the gate of the GAN device through the resistor R2, the DC-blocking capacitor C2, and the resistor R4. The non-homonymous end is connected to the cathode of the rectifier diode D4, and the anode of the diode D4 is connected to the emitter of the triode Q2 and then connected to the source of the GAN device. The base of the triode Q2 is connected to the anode of the diode D3, the cathode of the diode D3 is connected to the non-homonymous end of the secondary winding, and the resistor R3 is connected in parallel across the two ends of the diode D3. The collector of the triode Q2 is connected to the connection point of the resistor R2 and the capacitor C2. The anodes of the zener diode Z1 and the zener diode Z2 are connected together. The cathode of the zener diode Z1 is connected to the connection point of the DC-blocking capacitor C2 and the drive resistor R4, and the cathode of the zener diode Z2 is connected to the emitter of the triode Q2 to protect the gate of the GAN device. The two ends of the resistor R8 are respectively connected to the cathodes of the zener diode Z1 and the zener diode Z2 to discharge the gate capacitance of the GAN device.
2. The GaN device bridge arm isolation drive circuit according to claim 1, characterized in that: The PWM signal from the control circuit drives the conduction and cutoff of the triode Q1. When the triode Q1 conducts, the control power supply is applied to the primary winding of the transformer. The secondary side of the transformer starts to transfer energy. The secondary winding charges the gate capacitance of the GaN device, realizing the turn-on of the GaN device. The diode D4 conducts, accelerating the cutoff of the turn-off triode Q2. The voltage of the DC-blocking capacitor C2 gradually rises until it is fully charged during the conduction of Q1. The gate voltage of the GaN device gradually decreases, and the decreased amplitude is equal to the charging voltage of C2. When the triode Q1 turns off, the diode D4 turns off, the transformer stops transferring energy, accelerating the conduction of the triode Q2. The DC-blocking capacitor C2 is equivalent to a voltage source, and the stored energy is reversely charged to the gate capacitance of the GaN device through the triode Q2, accelerating the turn-off of the GaN device. The energy stored in the transformer is reset through the reset winding, and the energy is fed back to the control power supply.
3. The GaN device leg isolation drive circuit according to claim 1, wherein: By changing the turn ratio setting of the transformer and the capacitance of the DC-blocking capacitor, the required driving voltage amplitude of the GaN device is obtained.
4. The GaN device bridge arm isolation drive circuit according to claim 1, characterized in that: A capacitor C1 is connected between the control power supply VCC and the control return line for filtering to smooth the auxiliary power supply voltage.
5. The GaN device bridge arm isolation drive circuit according to claim 1, characterized in that: The voltage regulator diode Z1 conducts when the driving voltage or the glitch ringing is higher than the required value of the GaN device gate, preventing the GaN device gate from breakdown.
6. The GaN device leg isolation drive circuit according to claim 1, wherein: Resistors R1 and R3 control the turn-on speed of transistors Q1 and Q2; diodes D2 and D3 accelerate the turn-off speed of transistors Q1 and Q2.
7. The GaN device leg isolation drive circuit according to claim 1, wherein: The full-bridge power circuit includes GaN devices M1 to M4. M1 and M2 form a bridge arm, and M4 and M3 form a bridge arm; one isolated driving circuit is used to drive M1 and M3, and the other isolated driving circuit is used to drive M2 and M4.
8. A spacecraft power supply system, characterized in that: It includes the GaN device bridge arm isolated driving circuit according to any one of claims 1 to 7.
9. A ground electronic device, characterized in that: It includes the GaN device bridge arm isolated driving circuit according to any one of claims 1 to 7.