Grid driving negative voltage generation circuit, power conversion system and method

Abstract

The invention relates to the technical field of automatic control, in particular to a grid drive negative voltage generation circuit and a power conversion system and method. Comprising a high-frequency transformer used for isolating a PWM driving signal; the negative voltage generating capacitor is connected to the secondary side of the high-frequency transformer and is used for generating turn-off negative voltage; and the at least one clamping diode is connected in parallel with the secondary side of the high-frequency transformer and the negative voltage generation capacitor and is used for stabilizing the generated negative voltage. By introducing the negative voltage generation circuit, the GaN power device can obtain a stable negative voltage of about-0.5 V when being turned off, which is beneficial for accelerating the turn-off speed of the GaN device and reducing the switching loss. Experimental results show that after the driving circuit is adopted, the conversion efficiency of the power module reaches 92% under the rated working condition and is improved by more than 7% compared with a traditional product.

Description

Technical Field

[0001] The present invention relates to the field of automatic control technology, and in particular to a gate drive negative voltage generating circuit, a power conversion system and a method. Background Art

[0002] In recent years, whether in the field of aerospace, electric vehicle onboard chargers or communication power supplies, higher requirements have been put forward for switching power supplies. High reliability, high efficiency and high power density have become the eternal pursuit of switching power supplies. Improving the efficiency of switching power supplies mainly starts from two points: one is to improve the circuit topology, and the other is to select switching devices and magnetic devices with lower losses. Similarly, improving the power density of the converter can, on the one hand, select power devices with faster switching speeds, and on the other hand, reduce the volume of magnetic components. The core of these two points is switching devices with higher switching speeds and lower losses. As the core component of the power supply system, power devices are crucial to achieving low-power, energy-saving, high-reliability and low-cost power supply design. Their reliable shutdown and startup affect the safe operation of the entire power supply product.

[0003] With the development of semiconductor technology, the performance of silicon-based power devices has gradually approached the material limit boundary. Wide-bandgap semiconductor materials such as Gallium Nitride (GaN) are a new generation of semiconductor materials that have emerged in the past two decades and have many performance advantages. Compared with the physical properties of Si materials, GaN materials have the advantages of wide bandgap width, high melting point, high breakdown field strength, and fast electron saturation drift velocity. GaN power devices can be used to achieve high-frequency, high-efficiency, and high-power density switching power supplies.

[0004] To improve efficiency, the primary switch of high-density power products uses GaN power devices to replace traditional Si-based power devices, and the output end also uses a secondary rectification topology with synchronous rectification function. However, the existing GaN devices and drive circuits are basically implemented with imported components. In the context of localization, a gate drive negative voltage generation circuit designed with discrete devices is needed to meet the GaN switch drive requirements for space applications. In addition, compared with traditional silicon-based devices, GaN power devices have the characteristics of low threshold voltage, small controllable range of gate-source voltage, and high sensitivity to parasitic parameters, which can easily cause the device to be mistakenly turned on due to noise or disturbance of the drive signal, reducing system reliability and stability. Therefore, it is particularly important to design a drive circuit that can maintain the normal operation of GaN and ensure that the gate voltage has a sufficiently large safety margin. Summary of the invention

[0005] The present invention provides a gate drive negative voltage generating circuit, the purpose of which is to design a driving circuit capable of maintaining the normal operation of GaN and ensuring that the gate voltage has a sufficiently large safety margin.

[0006] To achieve the above object, the technical solution of the present invention is:

[0007] A gate drive negative voltage generating circuit, comprising:

[0008] A high-frequency transformer T1 is used to isolate the PWM drive signal;

[0009] a negative voltage generating capacitor C3, connected to the secondary side of the high frequency transformer, for generating a shutdown negative voltage;

[0010] at least one clamping diode D3 connected in parallel with the secondary side of the high frequency transformer and the negative voltage generating capacitor for stabilizing the generated negative voltage;

[0011] The circuit generates a negative voltage of -0.5V at the gate of the GaN power device through the cooperation of the above components, accelerates the turn-off speed of the GaN device, improves the conversion efficiency, and ensures that the system is not affected by oscillation caused by parasitic parameters and malfunctions under high-frequency conditions.

[0012] Furthermore, it also includes:

[0013] One or more triodes for assisting in controlling and regulating the drive signal;

[0014] One or more resistors and capacitors to further optimize the shape and stability of the drive waveform.

[0015] Furthermore, the high-frequency transformer has a specific transformation ratio, which is used to reduce the higher voltage output by the PWM control chip to a lower voltage range suitable for driving the GaN device.

[0016] Furthermore, the design of the negative voltage generating capacitor and the clamping diode can ensure that the GaN power device is in a safe off state during the entire off cycle, eliminating the risk of mis-turning on.

[0017] Furthermore, the circuit is suitable for spacecraft application environments, has high reliability and the ability to resist single particle effects, and will not be affected by the space environment.

[0018] Furthermore, the circuit is applied to a primary input voltage of 20V to 50V.

[0019] Furthermore, the power module adopts a resonant forward isolation topology, the main power transformer uses an EC type transformer produced by DMEGC, and the core material is DMR50B high-frequency magnetic material.

[0020] Furthermore, the MOS tubes and synchronous rectification MOS tubes in the power module are both domestically produced 200V series GaN tubes to improve conversion efficiency.

[0021] Furthermore, the system is suitable for application scenarios requiring high reliability, high efficiency and high power density, especially in the aerospace field.

[0022] Furthermore, by providing a negative voltage of -0.5V to ensure reliable shutdown of the GaN power device, the conversion efficiency and reliability of the entire system are improved.

[0023] The beneficial effects achieved by the present invention are:

[0024] A power conversion system, by introducing a negative voltage generating circuit, a GaN power device can obtain a stable negative voltage of about -0.5V when it is turned off, which helps to accelerate the turn-off speed of the GaN device and reduce switching losses. Experimental results show that after adopting the driving circuit of the present invention, the conversion efficiency of the power module reaches 92% under rated conditions, which is more than 7 percentage points higher than that of traditional products.

[0025] The present invention provides a gate drive negative voltage generating circuit. Since GaN power devices have faster switching speeds and lower parasitic parameters, the power supply system can operate at a higher frequency. The driving circuit of the present invention supports switching frequencies increased from 300KHz to more than 800KHz, thereby reducing the volume of magnetic components and increasing the power density of the entire system, which is doubled compared to the previous generation of products.

[0026] The present invention discloses a gate drive negative voltage generating circuit. The threshold voltage of GaN power devices is low, and they are easily affected by driving signal noise or disturbance and may be turned on by mistake. The present invention ensures that under high frequency conditions, oscillation caused by parasitic parameters will not cause false operation, thereby ensuring the reliability and stability of the system. In addition, the circuit keeps the VGS voltage below 0V during the off cycle, further eliminating the risk of false turn-on.

[0027] The present invention provides a gate drive negative voltage generating circuit. The gate drive negative voltage generating circuit of the present invention is completely based on discrete device design, the circuit is simple and reliable, has high anti-interference ability and good environmental adaptability. In particular, in the spacecraft application environment, the circuit is insensitive to single particle effects and is not affected by space radiation. After strict environmental test verification, it is proved that it can meet the high reliability requirements of spacecraft products.

[0028] The present invention discloses a gate drive negative voltage generating circuit. Existing GaN devices and driving circuits mostly rely on imported components. Under the background of localization, the present invention successfully realizes a gate drive negative voltage generating circuit designed with domestically produced discrete devices. This breakthrough not only reduces costs, but also improves the independent controllability of related domestic industries and promotes the technological progress of high-performance power conversion systems.

[0029] The present invention discloses a gate drive negative voltage generating circuit. By adopting the driving circuit of the present invention, the new generation of 150W series GaN power module products not only has a significant improvement in performance, but also has an advantage in market competitiveness. The high efficiency, high reliability and high power density of the product make it suitable for a variety of high-end application scenarios, such as aerospace, electric vehicles, communication equipment, etc., providing users with a better choice. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0031] Figure 1 The invention is a circuit diagram for generating a gate drive negative voltage.

[0032] Figure 2 This is the power supply block diagram.

[0033] Figure 3 This is a comparison diagram of the negative voltage generating circuit effect.

[0034] Figure 4 This is the measured effect diagram of the negative pressure generating circuit.

[0035] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back...), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0038] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, if the meaning of "and / or" appearing in the full text is to include three parallel solutions, taking "A and / or B" as an example, it includes solution A, or solution B, or a solution that satisfies both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in the field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0039] A gate drive negative voltage generating circuit, comprising:

[0040] A high-frequency transformer T1 is used to isolate the PWM drive signal;

[0041] A negative voltage generating capacitor C3, connected to the secondary side of the high frequency transformer, for generating a shutdown negative voltage;

[0042] at least one clamping diode D3 connected in parallel with the secondary side of the high frequency transformer and the negative voltage generating capacitor for stabilizing the generated negative voltage;

[0043] The circuit generates a negative voltage of -0.5V at the gate of the GaN power device through the cooperation of the above components, accelerates the turn-off speed of the GaN device, improves the conversion efficiency, and ensures that the system is not affected by oscillation caused by parasitic parameters and malfunctions under high-frequency conditions.

[0044] Furthermore, it also includes:

[0045] One or more triodes for assisting in controlling and regulating the drive signal;

[0046] One or more resistors and capacitors to further optimize the shape and stability of the drive waveform.

[0047] Furthermore, the high-frequency transformer has a specific transformation ratio, which is used to reduce the higher voltage output by the PWM control chip to a lower voltage range suitable for driving the GaN device.

[0048] Furthermore, the design of the negative voltage generating capacitor and the clamping diode can ensure that the GaN power device is in a safe off state during the entire off cycle, eliminating the risk of mis-turning on.

[0049] Furthermore, the circuit is suitable for spacecraft application environments, has high reliability and the ability to resist single particle effects, and will not be affected by the space environment.

[0050] Furthermore, the circuit is applied to a primary input voltage of 20V to 50V.

[0051] Furthermore, the power module adopts a resonant forward isolation topology, the main power transformer uses an EC type transformer produced by DMEGC, and the core material is DMR50B high-frequency magnetic material.

[0052] Furthermore, the MOS tubes and synchronous rectification MOS tubes in the power module are both domestically produced 200V series GaN tubes to improve conversion efficiency.

[0053] Furthermore, the system is suitable for application scenarios requiring high reliability, high efficiency and high power density, especially in the aerospace field.

[0054] Furthermore, by providing a negative voltage of -0.5V to ensure reliable shutdown of the GaN power device, the conversion efficiency and reliability of the entire system are improved.

[0055] like Figure 2 As shown, the present invention designs a new generation 150W series GaN power module product with a primary input voltage of 20V to 50V and an output voltage of 28V, and the product conversion efficiency is better than 90%.

[0056] The power topology adopts the "resonant forward" isolation topology. The main power transformer adopts the EC type transformer produced by Dongmei Corporation. The core material is DMR50B high-frequency magnetic material. The MOS tube chooses the domestically produced 200V series GaN tube. In order to improve the conversion efficiency, the synchronous rectification MOS tube also chooses the 200V series GaN tube.

[0057] The primary side switch MOS tube of the power supply is "isolated" from the PWM control chip, and the output level of the PWM control chip does not match. The driving output of the PWM control chip is about 0 to 10V, and the GaN device requires a driving voltage of about -0.5 to 5V. Therefore, in the design of the driving circuit, a high-frequency transformer is used to drive the isolation method, and the driving voltage is reduced by the transformer ratio. In order to ensure a negative voltage drive of about -0.5V, a negative voltage generating capacitor is added, and a clamping diode circuit is designed, such as Figure 1 shown.

[0058] like Figure 1 As shown in the figure, the negative voltage generating circuit is composed of capacitors and diodes. On the basis of the traditional isolation drive, the negative voltage generating circuit is added to shift the overall amplitude of the driving waveform down by about -0.5V, ensuring that the switch tube is in the off cycle, VGS The voltage is lower than 0 V to ensure that the device can be shut down reliably. When other parameters remain unchanged, the waveform without negative voltage generating circuit and the simulation waveform with negative voltage generating circuit are as follows: Figure 3 shown.

[0059] Depend on Figure 3 It can be seen that when there is no negative voltage generating circuit (green), the driving signal is around 0V when turned off. After adding the negative voltage generating circuit, the driving waveform moves down by about 0.5V as a whole, and the turn-off waveform is reduced to about -0.6V, which can ensure that the GaN power device is in a safe shutdown state during the entire turn-off cycle and eliminate the risk of mis-turn-on.

[0060] Based on the design of the above drive scheme and other power circuits, the development of a new generation of GaN series 150W power module products has been completed. The product conversion efficiency has reached 92% under rated conditions, which is more than 7 percentage points higher than that of traditional products. The product has been verified by environmental tests and has passed space single particle and total dose simulation tests, proving that this drive circuit can meet space applications.

[0061] This drive circuit is completely designed based on discrete devices. The circuit is simple and reliable. After experimental verification, it is proved that its effect meets the driving requirements of high reliability, high efficiency and high power density switching power supply devices.

[0062] The above descriptions are only optional embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent structural changes made using the contents of the present invention's specification and drawings, or directly / indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A gate drive negative voltage generating circuit, characterized in that: include: A high-frequency transformer T1 is used to isolate the PWM drive signal; a negative voltage generating capacitor C3, connected to the secondary side of the high frequency transformer, for generating a shutdown negative voltage; at least one clamping diode D3 connected in parallel with the secondary side of the high frequency transformer and the negative voltage generating capacitor for stabilizing the generated negative voltage; The circuit generates a negative voltage of -0.5V at the gate of the GaN power device through the cooperation of the above components, accelerates the turn-off speed of the GaN device, improves the conversion efficiency, and ensures that the system is not affected by oscillation caused by parasitic parameters and malfunctions under high-frequency conditions.

2. The gate drive negative voltage generating circuit according to claim 1, characterized in that: Also includes: One or more triodes for assisting in controlling and regulating the drive signal; One or more resistors and capacitors to further optimize the shape and stability of the drive waveform.

3. The gate drive negative voltage generating circuit according to claim 2, characterized in that: The high-frequency transformer has a specific transformation ratio and is used to reduce the higher voltage output by the PWM control chip to a lower voltage range suitable for driving the GaN device.

4. The gate drive negative voltage generating circuit according to any one of claim 3, characterized in that: The design of the negative voltage generating capacitor and the clamping diode can ensure that the GaN power device is in a safe off state during the entire off cycle, eliminating the risk of mis-turning on.

5. The gate drive negative voltage generating circuit according to any one of claim 4, characterized in that: The circuit is suitable for spacecraft application environment, has high reliability and single-particle effect resistance, and will not be affected by the space environment.

6. The gate drive negative voltage generating circuit according to any one of claim 5, characterized in that: This circuit is used for primary input voltage of 20V~50V.

7. The gate drive negative voltage generating circuit according to claim 6, characterized in that: The power module adopts a resonant forward isolation topology, the main power transformer uses an EC type transformer produced by DMEGC, and the core material is DMR50B high-frequency magnetic material.

8. The gate drive negative voltage generating circuit according to claim 7, characterized in that: The MOS tubes and synchronous rectification MOS tubes in the power module are both domestically produced 200V series GaN tubes to improve conversion efficiency.

9. A power conversion system comprising the gate drive negative voltage generating circuit according to any one of claims 1 to 8, characterized in that: The system is used in applications requiring high reliability, high efficiency and high power density.

10. A method of using the gate drive negative voltage generating circuit according to any one of claims 1 to 8, characterized in that: By providing a negative voltage of -0.5V, the GaN power device can be reliably turned off, thereby improving the conversion efficiency and reliability of the entire system.

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