Dead time control method and system for high frequency gallium nitride devices

Abstract

The application relates to the technical field of high-frequency gallium nitride device control, and discloses a dead time control method and system for a high-frequency gallium nitride device, the method is used for a resonant converter, and comprises the following steps: determining a dead current; based on the dead current, in combination with parasitic parameters of the high-frequency gallium nitride device, determining a discharge time of a source-drain voltage of the high-frequency gallium nitride device within a dead time; based on the discharge time, constructing a dead time control model; for the resonant converter working in real time, after an output voltage of the resonant converter reaches a steady state, acquiring a working frequency and an output current of the resonant converter, inputting the dead time control model, and outputting an optimized dead time. The system corresponds to the method. The application solves the technical problem that fixed dead time control in the prior art usually greatly increases switching loss of the high-frequency gallium nitride device, causes the high-frequency gallium nitride device to generate a large amount of heat, and further reduces the overall efficiency of the resonant converter.

Description

Technical Field

[0001] This application relates to the field of gallium nitride device control technology, specifically a dead-time control method and system for high-frequency gallium nitride devices. Background Technology

[0002] A suitable dead time is a prerequisite for achieving Zero-Show (ZVS). In order to ensure the safe operation of the converter and meet the requirements of ZVS, in engineering, a fixed and excessively long dead time is usually set considering the worst-case scenario. Due to the unique structure of gallium nitride (GaN) devices, their reverse conduction voltage is typically several times higher than that of silicon-based devices. Therefore, fixed dead-time control usually significantly increases the switching losses of GaN devices, leading to severe overheating and further reducing the overall efficiency of the resonant converter. Summary of the Invention

[0003] The purpose of this application is to provide a dead-time control method and system for high-frequency gallium nitride devices, so as to solve the technical problem that fixed dead-time control in the prior art usually greatly increases the switching losses of high-frequency gallium nitride devices, resulting in severe heat generation of high-frequency gallium nitride devices and further reducing the overall efficiency of resonant converters.

[0004] To achieve the above objectives, this application provides a dead-time control method for high-frequency gallium nitride (GaN) devices used in resonant converters, comprising: Based on the topology of the resonant converter, the dead zone current is determined; based on the dead zone current and combined with the parasitic parameters of the high-frequency gallium nitride device, the discharge time of the source-drain voltage of the high-frequency gallium nitride device during the dead zone time is determined. Based on the discharge time, a dead-time control model is constructed with the operating frequency of the high-frequency gallium nitride device and the output current of the resonant converter as inputs and the optimized dead-time of the high-frequency gallium nitride device as output. For a resonant converter operating in real time, after the output voltage of the resonant converter reaches a steady state, the operating frequency of the high-frequency gallium nitride device and the output current of the resonant converter are obtained, input into the dead time control model, and the optimized dead time is output.

[0005] Preferably, the determination of the dead-zone current based on the resonant converter topology includes: Establish the equivalent circuit for the dead-time operation of high-frequency gallium nitride devices in ZVS mode corresponding to the topology of the resonant converter; Based on the equivalent circuit, and combined with the constraint relationship between the output current, resonant current and excitation current of the resonant converter, the resonant current is determined. Based on the resonant current and the duty cycle of the high-frequency gallium nitride (GaN) device, an explicit expression for the dead zone current is determined to calculate the dead zone current.

[0006] Preferably, when the equivalent circuit is the equivalent circuit corresponding to a half-bridge LLC resonant converter, the explicit expression for the dead-time current is: in: For the determined dead zone current, For resonant current, For the duty cycle of a high-frequency gallium nitride (GaN) device, This refers to the turns ratio of the primary to the secondary side of the resonant transformer. The output voltage of the resonant converter. For magnetizing inductance, The resonant frequency and angular velocity of the resonant network. This is the output current of the resonant converter.

[0007] Preferably, the parasitic parameter is the output capacitance of a high-frequency gallium nitride device.

[0008] Preferably, the determination of the discharge time of the source-drain voltage of the high-frequency gallium nitride device within the dead time, based on the dead-zone current and combined with the parasitic parameters of the high-frequency gallium nitride device, includes: Obtain the parasitic parameters of the high-frequency gallium nitride device, including the output capacitance of the high-frequency gallium nitride device; Based on the output capacitance, input voltage, and dead zone current of a high-frequency gallium nitride device, an explicit expression for the discharge time is determined to calculate the discharge time.

[0009] Preferably, when the equivalent circuit is the equivalent circuit corresponding to a half-bridge LLC resonant converter, the explicit expression for the discharge time is: in, Discharge time, For the output capacitor of high-frequency gallium nitride devices, The input voltage of the resonant converter. This refers to the turns ratio of the primary to the secondary side of the resonant transformer. The output voltage of the resonant converter. For magnetizing inductance, This refers to the operating frequency of high-frequency gallium nitride devices. The resonant frequency and angular velocity of the resonant network. This is the output current of the resonant converter.

[0010] Preferably, the dead time control model is determined based on an explicit expression of the discharge time.

[0011] Preferably, the dead-time control model is optimized based on the action delay of high-frequency gallium nitride devices.

[0012] As a preferred option, the explicit expression for the optimized dead time output by the optimized dead time control model is as follows: in: The optimized dead time is the output of the optimized dead time control model. For the output capacitor of high-frequency gallium nitride devices, The input voltage of the resonant converter. This refers to the turns ratio of the primary to the secondary side of the resonant transformer. The output voltage of the resonant converter. For magnetizing inductance, This refers to the operating frequency of high-frequency gallium nitride devices. The resonant frequency and angular velocity of the resonant network. The output current of the resonant converter. This represents the turn-off delay time of a high-frequency gallium nitride device.

[0013] To achieve the above objectives, this application also provides a dead-time control system for high-frequency gallium nitride devices, which applies the dead-time control method for high-frequency gallium nitride devices as described above, including: The data analysis module is used to determine the dead zone current based on the topology of the resonant converter; based on the dead zone current and combined with the parasitic parameters of the high-frequency gallium nitride device, the discharge time of the source-drain voltage of the high-frequency gallium nitride device during the dead time is determined. The model building module is used to construct a dead-time control model based on the discharge time, with the operating frequency of the high-frequency gallium nitride device and the output current of the resonant converter as inputs and the optimized dead time of the high-frequency gallium nitride device as output. The control optimization module, for a resonant converter operating in real time, obtains the operating frequency of the high-frequency gallium nitride device and the output current of the resonant converter after the output voltage of the resonant converter reaches a steady state, inputs the dead time control model, and outputs the optimized dead time.

[0014] Beneficial effects: The dead-time control method and system for high-frequency gallium nitride (GaN) devices in this application establish the GaN ZVS equivalent circuit of the topology during the dead time through the equivalent model of the high-frequency GaN device and the analysis of the working principle of the topology, and solve the source-drain voltage of the device. Discharge time Explicit expression. Combined with the LLC topology, it was verified that this embodiment does not require any additional detection hardware circuitry. By adding a dead-time control model to the original closed-loop PFM control algorithm, the results can reduce the additional reverse conduction loss of high-frequency gallium nitride devices in the half-bridge LLC resonant converter during the dead time, improve the heating problem of high-frequency gallium nitride devices in high power density applications, and significantly improve overall efficiency and the stability of high-frequency gallium nitride devices during operation, thus contributing to the safe and reliable operation of power electronic devices. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a flowchart of the dead-time control method for high-frequency gallium nitride devices provided in this embodiment; Figure 2 The diagram shows the equivalent circuit of a high-frequency gallium nitride device LLC resonant topology during the dead time, as provided in this embodiment. In the figure: (a) shows the resonant capacitor and resonant inductor starting to charge and entering the resonant state; (b) shows the first mode of the switching mode; (c) shows the second mode of the switching mode. Figure 3 This is a block diagram of a dead-time control system for a high-frequency gallium nitride device provided in this embodiment; in the diagram: 10, data analysis module; 20, model building module; 30, control optimization module; Figure 4 The source-drain voltage of the high-frequency gallium nitride device in the half-bridge LLC topology provided in this embodiment. and gate-source voltage Waveform; in the figure: (a) (b) (c) .

[0017] The implementation, functional features, and advantages of this invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0018] The technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0019] In this document, the term "comprising" is intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0020] This embodiment discloses a dead-time control method and system for high-frequency gallium nitride (GaN) devices. In simple terms, it is a dynamic dead-time control technology for resonant converters using high-frequency GaN devices, specifically a verified dynamic dead-time control technology for half-bridge LLC resonant converters using high-frequency GaN devices. In summary, the technical principle of this embodiment is: based on the equivalent model of the high-frequency GaN device and the working principle of the LLC circuit topology, the soft-switching mechanism of the high-frequency GaN device in the LLC topology during the dead time is analyzed, and the source-drain voltage of the high-frequency GaN device is solved. Dead zone discharge time Explicit expression; the output capacitance of high-frequency gallium nitride devices can be obtained by consulting the device datasheet. The parameters and specific operating conditions were substituted into an explicit expression, and a simulation model was built in Simulink software to verify the accuracy of the explicit expression. This embodiment also discloses a dead-time control model for optimizing the dead time of high-frequency gallium nitride (GaN) devices. This model can effectively reduce reverse conduction caused by excessively long dead times in high-frequency GaN devices, reduce switching losses, and improve the operating stability of high-frequency GaN devices and the overall efficiency of resonant converters. It is particularly significant for the design of high-frequency, high-density resonant converters.

[0021] The application scenarios of the dead-time control method and system for high-frequency gallium nitride devices in this embodiment will now be described to facilitate understanding of the improvements in this embodiment.

[0022] With the rapid rise of artificial intelligence technology, the demand for computing power in data centers is increasing daily. LLC resonant converters are currently the mainstream DC / DC topology for data center power supplies, becoming a major research focus. LLC resonant topologies can achieve voltage isolation between the input and output of the resonant converter, while controlling the power devices to operate in ZVS soft-switching mode, greatly reducing switching losses and improving the overall system efficiency. Thanks to the development of gallium nitride (GaN) power devices, the operating frequency of LLC resonant converters has been further increased; furthermore, in some applications, transformer leakage flux is even used to replace the resonant inductor in the LLC resonant network, all of which improve the system's power density. Therefore, LLC resonant converters based on high-frequency GaN devices are an important technology for achieving high power density power supplies and have significant application prospects in the field of artificial intelligence.

[0023] In light of the aforementioned structural uniqueness of gallium nitride (GaN) devices, their reverse conduction voltage is typically several times higher than that of silicon-based devices. Therefore, fixed dead-time control often results in significant increases in switching losses, severe overheating, and further reduction in the overall efficiency of the converter. This embodiment analyzes typical prior art to facilitate understanding of the improvements in this embodiment.

[0024] Existing technologies involve sampling the voltage of the bridge arm switching nodes, the bridge arm voltage sequence, and the freewheeling current of the lower transistor to calculate the voltage transient slope value and thus determine the zero-voltage switching margin. This technique requires adding numerous sensors to the bridge arm, significantly increasing system size, hardware design, and manufacturing costs. Furthermore, the obtained slope value is only an approximation, resulting in substantial errors in practical engineering applications, making it unsuitable for high-power-density and low-cost resonant converters. Other existing technologies combine sampled input voltage, output voltage, and current to derive complex high-order formulas. Since these complex formulas and equations are not explicit expressions, iterative calculations using Matlab software are required to obtain the soft-switching time. This technique demands significant hardware computing power and is difficult to deploy in high-frequency resonant converter terminals. To address these shortcomings and analysis, this embodiment discloses a dead-time control method and system for high-frequency gallium nitride devices.

[0025] The dead-time control method for high-frequency gallium nitride devices in this embodiment will now be described.

[0026] Reference Figure 1 , Figure 1 This is a flowchart of the dead-time control method for high-frequency gallium nitride devices provided in this embodiment.

[0027] like Figure 1As shown, in a first aspect, this embodiment discloses a dead-time control method for a high-frequency gallium nitride (GaN) device used in a resonant converter, comprising: S10: Based on the topology of the resonant converter, determine the dead zone current; based on the dead zone current and combined with the parasitic parameters of the high-frequency gallium nitride device, determine the discharge time of the source-drain voltage of the high-frequency gallium nitride device within the dead zone time.

[0028] Specifically, the parasitic parameter is the output capacitance of a high-frequency gallium nitride (GaN) device. In practical applications, the parasitic parameters of a high-frequency GaN device can be determined based on the device datasheet, i.e., the output capacitance is determined based on the datasheet. .

[0029] Gallium nitride high electron mobility transistors (GaN-HEMTs), which are the high-frequency gallium nitride devices referred to in this embodiment, have unique manufacturing processes and wide bandgap material properties, resulting in a high output capacitance. With significantly lower voltages than silicon-based devices, high-frequency gallium nitride (GaN) devices can achieve high-frequency switching. Their reverse conduction characteristics also differ from the equivalent diode of silicon-based devices. The reverse conduction of high-frequency GaN devices is formed by an approximate diode whose voltage drop is dominated by the external circuitry, connected in series with the body resistance in the on-state. Therefore, entering the reverse conduction region results in a large on-state voltage drop. Based on this analysis, a circuit model of the high-frequency GaN device is derived. In this embodiment, the circuit model of the high-frequency GaN device is used to derive an explicit expression for the dead-time current, enabling its deployment at the terminal of a high-frequency resonant converter.

[0030] Reference Figure 2 , Figure 2 The diagram shows the equivalent circuit of a high-frequency gallium nitride device LLC resonant topology in the dead time provided in this embodiment; in the figure: (a) shows the resonant capacitor and resonant inductor starting to charge and enter the resonant state; (b) shows the first mode of the switching mode; (c) shows the second mode of the switching mode.

[0031] Specifically, based on the topology of the resonant converter, the dead-time current is determined, including: Establish the equivalent circuit for the dead time operation of the high-frequency gallium nitride device ZVS corresponding to the topology of the resonant converter.

[0032] Based on the equivalent circuit, and considering the constraint relationship between the output current, resonant current, and excitation current of the resonant converter, the resonant current is determined.

[0033] Based on the resonant current and the duty cycle of the high-frequency gallium nitride (GaN) device, an explicit expression for the dead zone current is determined to calculate the dead zone current.

[0034] In this embodiment, taking a half-bridge LLC resonant converter as an example, an equivalent circuit for the ZVS operation of a high-frequency gallium nitride (GaN) device during the dead time of the LLC topology is established. The main circuit of the half-bridge LLC resonant converter containing the high-frequency GaN device includes a GaN inverter bridge circuit, an LLC resonant network composed of a resonant inductor, a resonant capacitor, and a magnetizing inductor, and a rectifier circuit. When the high-frequency GaN device operates in ZVS mode, the circuit is divided into two switching modes. In mode one, when the upper GaN transistor of the inverter bridge is turned on and the lower transistor is turned off, the input voltage is connected to the LLC resonant network. At this time, the system circuit can be equivalent to an input DC source. With resonant capacitor Resonant inductor Magnetizing inductor The circuit is connected in series, with the load equivalent to the primary side via a transformer, approximating a DC voltage source. Connected in parallel across the magnetizing inductor; for high-frequency gallium nitride devices, the transistor on the inverter bridge Discharge, source-drain voltage The value drops to zero, and the output capacitor of the inverter bridge lower transistor... Charging, its source-drain voltage The current rises; at this time, the resonant capacitor and resonant inductor begin to charge and enter the resonant state, such as... Figure 2 As shown in (a), the resonant current The excitation current exhibits a sinusoidal change. Due to the output voltage of the resonant converter The clamping action exhibits a fixed upward slope; the output current of the resonant converter... The value remains constant, determined by the output voltage of the resonant converter. It is related to the equivalent AC load value, and the equivalent circuit diagram is as follows: Figure 2 As shown in (b) above. Mode two, until the inverter bridge transistor is turned off, the circuit enters a dead zone state, the input DC voltage is disconnected, and at this time the magnetizing inductor... Resonant inductor and resonant capacitor Series connection, light load operation at over-resonance and resonant current Greater than the excitation current Therefore, the equivalent primary voltage of the load It still exists; the equivalent circuit diagram is as follows: Figure 2 As shown in (c); due to the magnetizing inductance Larger than Therefore, the excitation current during the dead time Approximately constant, resonant current rapid decline and equal.

[0035] Thus far, this embodiment uses a high-frequency gallium nitride device in a half-bridge LLC resonant converter as an example to illustrate the equivalent circuit of the high-frequency gallium nitride device operating in the dead time (ZVS) corresponding to the established resonant converter topology.

[0036] Following the analysis above regarding the high-frequency gallium nitride devices in a half-bridge LLC resonant converter, the derivation of the explicit expression for the dead-time current in this embodiment will now be explained. Definition: The state where the upper transistor of the inverter bridge is on and the lower transistor is off is stage one; the state where both the upper and lower transistors are off is stage two. In stage one, the KCL and KVL laws apply, and the output current of the load resonant converter in stage two is also considered. With resonant current and excitation current Using the relationship as a constraint, we can obtain: in: The characteristic impedance of the main resonant network is: ; and These are the initial values ​​of the resonant inductance and resonant capacitance at time 0; It is the resonant frequency and angular velocity of the resonant network, with a value of ; This is the duty cycle of the gallium nitride device. Solving the system of equations, we obtain the exact explicit expression for the resonant current within one stage: Will Substituting the exact explicit expression for the resonant current within a stage, we can derive the explicit expression for the dead zone current.

[0037] Specifically, when the equivalent circuit is the equivalent circuit corresponding to a half-bridge LLC resonant converter, the explicit expression for the dead-time current is: in: For the determined dead zone current, For resonant current, For the duty cycle of a high-frequency gallium nitride (GaN) device, This refers to the turns ratio of the primary to the secondary side of the resonant transformer. The output voltage of the resonant converter. For magnetizing inductance, The resonant frequency and angular velocity of the resonant network. This is the output current of the resonant converter.

[0038] Thus, this embodiment, using a high-frequency gallium nitride device in a half-bridge LLC resonant converter as an example, illustrates the scheme for deriving the explicit expression of the dead-time current, providing a foundation for deriving the explicit expression of the discharge time.

[0039] The derivation of the explicit expression for the discharge time in this embodiment will now be explained.

[0040] Specifically, based on the dead-zone current and combined with the parasitic parameters of the high-frequency gallium nitride (GaN) device, the discharge time of the source-drain voltage within the dead-zone time of the high-frequency GaN device is determined, including: Obtain the parasitic parameters of the high-frequency gallium nitride device, including the output capacitance of the high-frequency gallium nitride device.

[0041] Based on the output capacitance, input voltage, and dead zone current of a high-frequency gallium nitride device, an explicit expression for the discharge time is determined to calculate the discharge time.

[0042] In the specific application of this embodiment, in response to the hardware characteristics of the high-frequency gallium nitride device, namely due to the output capacitance of the high-frequency gallium nitride device... Due to the existence of this, the resonant converter needs to set a dead time for the operation of the complementary two-channel devices. This embodiment is based on the output capacitor. Complete the derivation of the explicit expression for the discharge time.

[0043] Specifically, based on the explicit expression of the dead zone current in the aforementioned derived half-bridge LLC resonant converter, the explicit expression of the corresponding discharge time is determined.

[0044] Specifically, when the equivalent circuit is the equivalent circuit corresponding to a half-bridge LLC resonant converter, the explicit expression for the discharge time is: in, Discharge time, For the output capacitor of high-frequency gallium nitride devices, The input voltage of the resonant converter. This refers to the turns ratio of the primary to the secondary side of the resonant transformer. The output voltage of the resonant converter. For magnetizing inductance, This refers to the operating frequency of high-frequency gallium nitride devices. The resonant frequency and angular velocity of the resonant network. This is the output current of the resonant converter.

[0045] Thus, this embodiment, taking the analysis of high-frequency gallium nitride devices in a half-bridge LLC resonant converter as an example, illustrates the derivation of the explicit expression for the discharge time of the source-drain voltage of the gallium nitride device under over-resonance, providing a technical basis for the efficient online calculation of dead time.

[0046] Based on the above, the derivation of explicit expressions for dead-time current and discharge time provides a theoretical basis for greatly reducing computational costs in this embodiment and a technical basis for constructing a dead-time control model.

[0047] The dead-time control model of this embodiment will now be described.

[0048] S20: Based on the discharge time, a dead-time control model is constructed with the operating frequency of the high-frequency gallium nitride device and the output current of the resonant converter as inputs and the optimized dead time of the high-frequency gallium nitride device as output.

[0049] Specifically, the dead-time control model is determined based on an explicit expression of the discharge time.

[0050] In practice, the operation of high-frequency gallium nitride (GaN) devices differs significantly from simulation. Factors such as PCB routing, system design, device design, and manufacturing processes are all significant contributors to this non-ideal performance. For driver design, the most critical concern is the operating delay of high-frequency GaN devices, which primarily comprises two parts: the gate signal turn-on delay and the capacitance delay. The turn-off delay time after which discharge begins is a period of time. The time is typically around tens of nanoseconds; secondly, the gate signal is turned off. The charging start delay time after the capacitor delay time Typically, the former's time is much longer than the latter's, so the change in the latter can be ignored. In silicon-based MOSFET applications with long dead times, the action delay time is usually negligible. However, in high-frequency gallium nitride (GaN) device applications operating at higher frequencies, it needs to be strictly considered. In experimental setups with fixed-model high-frequency GaN devices and pre-designed PCBs, this action delay time remains relatively constant despite changes in operating conditions. Therefore, it is necessary to measure the turn-off delay time in advance. , which serves as the experimental correction variable in the explicit expression for dead-time optimization.

[0051] Specifically, the dead-time control model is optimized based on the action delay of high-frequency gallium nitride devices.

[0052] Taking into account the action delay, and following the aforementioned analysis of the LLV topology, this embodiment incorporates the discharge time within the dead zone of the source-drain voltage of the high-frequency gallium nitride device. Device turn-off delay time and specific operating conditions and device models The explicit expression for the optimized dead time output by the optimized dead time control model is as follows: in: The optimized dead time is the output of the optimized dead time control model. For the output capacitor of high-frequency gallium nitride devices, The input voltage of the resonant converter. This refers to the turns ratio of the primary to the secondary side of the resonant transformer. The output voltage of the resonant converter. For magnetizing inductance, This refers to the operating frequency of high-frequency gallium nitride devices. The resonant frequency and angular velocity of the resonant network. The output current of the resonant converter. This represents the turn-off delay time of a high-frequency gallium nitride device.

[0053] S30: For resonant converters operating in real time, after the output voltage of the resonant converter reaches a steady state, the operating frequency of the high-frequency gallium nitride device and the output current of the resonant converter are obtained, the dead time control model is input, and the optimized dead time is output.

[0054] In one specific application of this embodiment, the dead-time optimization control of a half-bridge LLC resonant converter using high-frequency gallium nitride devices is performed in the corresponding hardware, mainly including the following functional partitions: voltage closed-loop PFM control partition, output voltage steady-state determination partition, input and output voltage detection partition, output current acquisition partition, dead-time optimization calculation partition using sampled values, and dead-time processing partition. Specifically, in the explicit expression of the optimized dead-time output by the aforementioned optimized dead-time control model, the resonant network parameters and correction variables... It is a fixed value determined at the initial design stage, the discharge time within the dead zone of the source-drain voltage. The dead time varies constantly with the operating conditions of the resonant converter, controlled by variables such as the input voltage, the output voltage of the resonant converter, the output current of the resonant converter, and the circuit operating frequency. When the circuit load lightens, causing the output voltage of the resonant converter to rise, the voltage closed-loop PFM control zone operates, its internal PI integrator calculates, increases the frequency of the gallium nitride drive signal, and adjusts the dead time. Keep the output voltage of the resonant converter unchanged. The voltage drops; then the output voltage steady-state determination zone is entered, and the output voltage value of the resonant converter is sampled. The comparison continues until the absolute peak-to-peak output voltage of the resonant converter is reached. ,in, The output voltage of the designed rated resonant converter, To reduce the output voltage ripple coefficient of the resonant converter required for engineering applications, disable the voltage closed-loop PFM control partition enable signal. And enable the input / output voltage detection partition signal. Then the controller records internally Furthermore, the input voltage and the output current of the resonant converter The data acquisition partition yields two reliable values ​​for variables using a filtering algorithm. Specifically, this can be achieved by sampling before and after the controller's main frequency. The data is obtained by averaging the remaining values ​​after removing the two with the largest differences. These values ​​are then substituted into the sampled values ​​to calculate and output the dead-time discharge time of the high-frequency gallium nitride device. All variables output from the partitions in the dead-time optimization calculation are imported. The final result is output to the dead-time processing partition, where correction variables are added. The final optimized dead time is obtained. Change the dead time of the drive signal in the next cycle. .

[0055] Reference Figure 3 , Figure 3 The diagram shows the structure of the dead-time control system for high-frequency gallium nitride devices provided in this embodiment; in the diagram: 10, data analysis module; 20, model building module; 30, control optimization module.

[0056] like Figure 3 As shown, in a second aspect, this embodiment also discloses a dead-time control system for high-frequency gallium nitride devices, applying the dead-time control method for high-frequency gallium nitride devices as described above, including: Data analysis module 10 is used to determine the dead zone current based on the topology of the resonant converter; based on the dead zone current and combined with the parasitic parameters of the high-frequency gallium nitride device, it determines the discharge time of the source-drain voltage of the high-frequency gallium nitride device within the dead zone time. Model building module 20 is used to build a dead time control model based on discharge time, with the operating frequency of the high-frequency gallium nitride device and the output current of the resonant converter as inputs and the optimized dead time of the high-frequency gallium nitride device as output. The control optimization module 30, for the resonant converter operating in real time, after the output voltage of the resonant converter reaches a steady state, obtains the operating frequency of the high-frequency gallium nitride device and the output current of the resonant converter, inputs the dead time control model, and outputs the optimized dead time.

[0057] It should be noted that the dead-time control system for high-frequency gallium nitride devices in this embodiment corresponds to the aforementioned dead-time control method for high-frequency gallium nitride devices. Therefore, any content not specifically described in the dead-time control system for high-frequency gallium nitride devices in this embodiment, including but not limited to functional definitions, working principles, and technical effects, can be referred to the description in the aforementioned dead-time control method for high-frequency gallium nitride devices, and will not be repeated here.

[0058] Reference Figure 4 , Figure 4The source-drain voltage of the high-frequency gallium nitride device in the half-bridge LLC topology provided in this embodiment. and gate-source voltage Waveform; in the figure: (a) (b) (c) .

[0059] To verify the superiority of the dead-time control method and system for high-frequency gallium nitride devices in this embodiment, further verification was conducted using a pre-built experimental prototype. The specific parameters of the experimental prototype are as follows: Input... Rated output ,power resonant frequency resonant inductor resonant capacitor Transformer magnetizing inductance By varying the light load to stabilize the closed-loop operating frequency at 400kHz, 390kHz, and 380kHz, respectively, experimental measurements were performed on the source-drain voltages of the high-frequency gallium nitride devices in the half-bridge LLC topology. and gate-source voltage Waveform as Figure 4 As shown. In Figure 4 In (a) and (b), the left side represents the control group with a fixed dead time of 120 ns, while the right side represents the optimal dead times of 90 ns and 80 ns obtained by dead time control optimization in this embodiment; within the gray area of ​​the left figure, the gallium nitride source-drain voltage... After decreasing to 0, it continues to increase in the opposite direction, and then remains unchanged until the drive signal of the complementary switch arrives. This indicates that after the high-frequency gallium nitride device achieves ZVS, it enters the reverse conduction region until the dead zone ends. In the gray area of ​​the right figure, thanks to the accurate calculation of the dead time optimization model, the reverse conduction phenomenon in the dead time of the high-frequency gallium nitride device basically disappears, and it can just achieve ZVS operation. Figure 4 In (c), the optimized dead time of gallium nitride is exactly 120ns. In contrast, a fixed dead time of 100ns is used. In the gray area on the right, the phenomenon of insufficient ZVS operation due to insufficient dead time can also be observed.

[0060] It is clear that the dead-time control method and system for high-frequency gallium nitride devices in this embodiment can calculate an accurate and reliable dead-time optimization time based on the input / output sampling required for closed-loop control without adding extra hardware costs, while not affecting the inherent control strategy of the system. The advantage of this technical solution is that it can further reduce the dynamic loss of the device, which has important practical value for some applications with high system efficiency and power density requirements, and also provides a new research idea for optimizing the system efficiency of high-frequency electronic switching converters.

[0061] In summary, the dead-time control method and system for high-frequency gallium nitride (GaN) devices in this embodiment include: solving and optimizing the dead-time control model; when the load changes, real-time acquisition of the output current of the resonant converter and the real-time operating frequency of the high-frequency resonator are substituted into the dead-time control model to adaptively correct the dead-time of the drive waveform. This will help reduce switching losses under high operating voltage and high operating frequency, thereby improving the efficiency of the entire power electronic device. Specifically, this embodiment solves for the source-drain voltage of the device by simplifying the equivalent model of the high-frequency GaN device and the working principle of the LLC topology. Dead time Discharge time within The explicit expression considers the operating delay time of high-frequency gallium nitride devices in practical circuits, mainly in terms of the turn-off time. Based on this, a dead-time control model is obtained. Unlike existing technologies, this embodiment, through in-depth research on the operating modes of high-frequency gallium nitride devices within the dead time, reduces the order of some state variables to linearization within a specific time range, ultimately deriving a more accurate ZVS time. Explicit expressions can greatly reduce computational costs; at the same time, experimental measurements of the operation of high-frequency gallium nitride devices in the system provide accurate delay time for compensation and correction. The resulting dead-time optimization model can meet the dead-time requirements of ZVS operation under different operating conditions, while reducing the reverse conduction loss caused by redundant dead time, thereby reducing device dynamic losses and improving system efficiency.

[0062] This embodiment will now be described in conjunction with a complete implementation. In one implementation, this embodiment includes the following steps: A1: Locate the key parasitic parameters of the device in the datasheet for the corresponding gallium nitride model, specifically the output capacitance. This is to prepare for the establishment of an equivalent model of the device.

[0063] A2: Analyze the working mechanism of the LLC resonant topology, combine it with the device equivalent model in A1, draw the simplified equivalent circuit during the dead time, and proceed to step A3.

[0064] A3: Based on the simplified equivalent circuit of A2, substitute the output capacitance of the devices in A1. Using the KCL and KVL laws, the source-drain voltage and discharge time of high-frequency gallium nitride devices during the dead time are calculated. Explicit expressions.

[0065] A4: Test the turn-off delay time of high-frequency gallium nitride devices under rated operating conditions. Combined with the dead time of A3, source-drain voltage discharge time The explicit expression yields the dead-time control model.

[0066] A5: When the circuit operating conditions change, the system closed-loop control starts working. After the output voltage of the resonant converter reaches a steady state, the current operating frequency of the system is read. and sampled load current By substituting the operating parameters into the dead-time control model of A4, the optimal dead-time under this operating condition can be obtained. .

[0067] Compared with the prior art, this embodiment discloses a dead-time control method and system for high-frequency gallium nitride (GaN) devices. First, through an equivalent model of the high-frequency GaN device and analysis of the working principle of the LLC topology, the GaN ZVS equivalent circuit of the LLC topology during the dead time is established, and the source-drain voltage of the device is solved. Discharge time Explicit expression; then, gallium nitride action delay time is obtained through experimental measurement. The final optimized dead time is obtained by combining the results. This embodiment does not require any additional detection hardware circuitry. By incorporating a dead-time control model into the existing closed-loop PFM control algorithm, the resulting solution can reduce the additional reverse conduction loss of high-frequency gallium nitride devices in the half-bridge LLC resonant converter during the dead time. This improves the heating problem of high-frequency gallium nitride devices in high power density applications, significantly enhancing overall efficiency and the stability of high-frequency gallium nitride devices during operation, and is of great significance for the safe and reliable operation of power electronic devices.

[0068] In the embodiments provided in this application, it should be understood that the embodiments described herein can be implemented in hardware, software, firmware, middleware, code, or any suitable combination thereof. For hardware implementation, the processor may be implemented in one or more of the following: application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field-programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, other electronic units designed to implement the functions described herein, or combinations thereof. For software implementation, some or all of the processes of the embodiments may be performed by a computer program instructing the associated hardware. During implementation, the program may be stored in a computer-readable storage medium or transmitted as one or more instructions or code on a computer-readable storage medium. Computer-readable storage media include computer storage media and communication media, wherein communication media include any medium that facilitates the transmission of a computer program from one place to another. Storage media may be any available medium accessible to a computer. Computer-readable storage media may include, but are not limited to, RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage media or other magnetic storage devices, or any other medium capable of carrying or storing desired program code having the form of instructions or data structures and accessible to a computer.

[0069] Finally, it should be noted that the above description is only a preferred embodiment of this application and is not intended to limit this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A dead-time control method for a high-frequency gallium nitride (GaN) device used in a resonant converter, characterized in that, include: Determine the dead zone current based on the topology of the resonant converter; Based on the dead-zone current and combined with the parasitic parameters of the high-frequency gallium nitride device, the discharge time of the source-drain voltage of the high-frequency gallium nitride device during the dead-zone time is determined. Based on the discharge time, a dead-time control model is constructed with the operating frequency of the high-frequency gallium nitride device and the output current of the resonant converter as inputs and the optimized dead-time of the high-frequency gallium nitride device as output. For a resonant converter operating in real time, after the output voltage of the resonant converter reaches a steady state, the operating frequency of the high-frequency gallium nitride device and the output current of the resonant converter are obtained, input into the dead time control model, and the optimized dead time is output.

2. The dead-time control method for high-frequency gallium nitride devices according to claim 1, characterized in that, The topology based on the resonant converter determines the dead-zone current, including: Establish the equivalent circuit for the dead-time operation of high-frequency gallium nitride devices in ZVS mode corresponding to the topology of the resonant converter; Based on the equivalent circuit, and combined with the constraint relationship between the output current, resonant current and excitation current of the resonant converter, the resonant current is determined. Based on the resonant current and the duty cycle of the high-frequency gallium nitride (GaN) device, an explicit expression for the dead zone current is determined to calculate the dead zone current.

3. The dead-time control method for high-frequency gallium nitride devices according to claim 2, characterized in that, When the equivalent circuit is the equivalent circuit corresponding to a half-bridge LLC resonant converter, the explicit expression for the dead-time current is: in: For the determined dead zone current, For resonant current, For the duty cycle of a high-frequency gallium nitride (GaN) device, This refers to the turns ratio of the primary to the secondary side of the resonant transformer. The output voltage of the resonant converter. For magnetizing inductance, The resonant frequency and angular velocity of the resonant network. This is the output current of the resonant converter.

4. The dead-time control method for high-frequency gallium nitride devices according to claim 2, characterized in that, The parasitic parameter is the output capacitance of the high-frequency gallium nitride device.

5. The dead-time control method for high-frequency gallium nitride devices according to claim 2, characterized in that, The method of determining the discharge time of the source-drain voltage of a high-frequency gallium nitride device within the dead time, based on the dead-zone current and combined with the parasitic parameters of the high-frequency gallium nitride device, includes: Obtain the parasitic parameters of the high-frequency gallium nitride device, including the output capacitance of the high-frequency gallium nitride device; Based on the output capacitance, input voltage, and dead zone current of a high-frequency gallium nitride device, an explicit expression for the discharge time is determined to calculate the discharge time.

6. The dead-time control method for high-frequency gallium nitride devices according to claim 5, characterized in that, When the equivalent circuit is the equivalent circuit corresponding to a half-bridge LLC resonant converter, the explicit expression for the discharge time is: in, Discharge time, For the output capacitor of high-frequency gallium nitride devices, The input voltage of the resonant converter. This refers to the turns ratio of the primary to the secondary side of the resonant transformer. The output voltage of the resonant converter. For magnetizing inductance, This refers to the operating frequency of high-frequency gallium nitride devices. The resonant frequency and angular velocity of the resonant network. This is the output current of the resonant converter.

7. The dead-time control method for high-frequency gallium nitride devices according to claim 6, characterized in that, The dead-time control model is determined based on an explicit expression of the discharge time.

8. The dead-time control method for high-frequency gallium nitride devices according to claim 1, characterized in that, The dead-time control model is optimized based on the action delay of high-frequency gallium nitride devices.

9. The dead-time control method for high-frequency gallium nitride devices according to claim 8, characterized in that, The explicit expression for the optimized dead time output by the optimized dead time control model is: in: The optimized dead time is the output of the optimized dead time control model. For the output capacitor of high-frequency gallium nitride devices, The input voltage of the resonant converter. This refers to the turns ratio of the primary to the secondary side of the resonant transformer. The output voltage of the resonant converter. For magnetizing inductance, This refers to the operating frequency of high-frequency gallium nitride devices. The resonant frequency and angular velocity of the resonant network. The output current of the resonant converter. This represents the turn-off delay time of a high-frequency gallium nitride device.

10. A dead-time control system for high-frequency gallium nitride devices, employing the dead-time control method for high-frequency gallium nitride devices as described in any one of claims 1 to 9, characterized in that, include: The data analysis module is used to determine the dead zone current based on the topology of the resonant converter; Based on the dead-zone current and combined with the parasitic parameters of the high-frequency gallium nitride device, the discharge time of the source-drain voltage of the high-frequency gallium nitride device during the dead-zone time is determined. The model building module is used to construct a dead-time control model based on the discharge time, with the operating frequency of the high-frequency gallium nitride device and the output current of the resonant converter as inputs and the optimized dead time of the high-frequency gallium nitride device as output. The control optimization module, for a resonant converter operating in real time, obtains the operating frequency of the high-frequency gallium nitride device and the output current of the resonant converter after the output voltage of the resonant converter reaches a steady state, inputs the dead time control model, and outputs the optimized dead time.

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