Method and system for on-line gate leakage current monitoring of gaN power devices

Abstract

This application relates to the field of online health monitoring technology for wide-bandgap semiconductor power devices, and discloses an online gate leakage current monitoring method and system for GaN power devices. The method includes: extracting an average gate drive current, which is the average value of the instantaneous current flowing into or out of the gate of the GaN power device during a complete switching cycle; and obtaining the gate leakage current based on the average gate drive current for online gate leakage current monitoring of the GaN power device. This system corresponds to the method. This application fundamentally solves the core problems of insufficient resolution and inability to achieve early warning in traditional voltage detection methods; simultaneously, it employs source-series sampling and non-intrusive signal conditioning circuitry, avoiding the introduction of switching and voltage regulation circuits into the gate drive loop, thereby eliminating interference with parasitic parameters of the gate loop and ensuring its feasibility and reliability in high-frequency, high-sensitivity GaN power devices.

Description

Technical Field

[0001] This application relates to the field of online health monitoring technology for wide bandgap semiconductor power devices, specifically an online gate leakage current monitoring method and system for GaN power devices. Background Technology

[0002] With the surge in demand for high-frequency, high-efficiency power conversion in fields such as 5G communication and new energy vehicles, GaN (gallium nitride) devices have gained widespread application due to their superior high-frequency characteristics and power density. However, their gate structure is extremely sensitive to electrothermal stress, and even a small increase in gate leakage current is a key early sign of gate degradation. Existing monitoring methods are mostly based on silicon or silicon carbide device designs, facing challenges such as insufficient resolution, poor structural compatibility, and limited high-frequency adaptability, making them difficult to directly apply to GaN devices with higher switching frequencies and narrower gate voltage windows. Therefore, developing an online monitoring scheme that combines high resolution, high-frequency compatibility, and structural adaptability has become a key technical bottleneck in improving the reliability of GaN devices. Summary of the Invention

[0003] The purpose of this application is to provide an online gate leakage current monitoring method and system for GaN power devices, so as to solve the technical problem that the leakage current monitoring method in the prior art is difficult to be directly applied to GaN devices.

[0004] To achieve the above objectives, this application provides an online gate leakage current monitoring method for GaN power devices, comprising:

[0005] Extract the average gate drive current, which is the average value of the instantaneous current flowing into or out of the gate of the GaN power device during a complete switching cycle.

[0006] Based on the average gate drive current, the high-frequency transient gate current is converted into its positive and negative DC components, and the gate leakage current is calculated using the difference between the two components to perform online gate leakage current monitoring of GaN power devices.

[0007] Preferably, the average gate drive current includes a positive average gate drive current and a negative average gate drive current. The positive average gate drive current is the average value of the instantaneous current flowing into the gate of the GaN power device during a complete switching cycle, and the negative average gate drive current is the average value of the instantaneous current flowing out of the gate of the GaN power device during a complete switching cycle.

[0008] Preferably, the gate leakage current is obtained based on the average gate drive current, specifically the gate leakage current is equal to the difference between the positive average gate drive current and the negative average gate drive current.

[0009] Preferably, the mathematical expression for the forward average gate drive current is:

[0010]

[0011] in: The calculated average gate drive current, For the switching cycle, This refers to the instantaneous current flowing into the gate of the GaN power device;

[0012] The mathematical expression for the negative average gate drive current is:

[0013]

[0014] in: The calculated negative average gate drive current, For the switching cycle, This refers to the instantaneous current flowing out of the gate of the GaN power device.

[0015] Preferably, the online gate leakage current monitoring method is based on a detection circuit, which includes a leakage current extraction circuit and an operational amplifier circuit. The input terminal of the leakage current extraction circuit is connected to the gate of the GaN power device, and the output terminal of the leakage current extraction circuit is connected to the input terminal of the operational amplifier circuit. The output terminal of the operational amplifier circuit outputs a DC voltage signal that is proportional to the gate leakage current.

[0016] Preferably, the leakage current extraction circuit includes a first Schottky diode, a second Schottky diode, a first sampling resistor, a second sampling resistor, a first capacitor, and a second capacitor; wherein: the anode of the first Schottky diode and the cathode of the second Schottky diode are connected to form the input terminal of the leakage current extraction circuit, which is connected to the gate of the GaN power device; the cathode of the first Schottky diode, one end of the first sampling resistor, and one end of the first capacitor are connected; the anode of the second Schottky diode, one end of the second sampling resistor, and one end of the second capacitor are connected; the other ends of the first sampling resistor, the first capacitor, the second sampling resistor, and the second capacitor are all connected to the drive power supply ground; and: the connection point of the cathode of the first Schottky diode, one end of the first sampling resistor, and one end of the first capacitor forms the first output terminal of the leakage current extraction circuit, and the connection point of the anode of the second Schottky diode, one end of the second sampling resistor, and one end of the second capacitor forms the second output terminal of the leakage current extraction circuit, the output terminal of the leakage current extraction circuit includes the first output terminal and the second output terminal; and the resistance values ​​of the first sampling resistor and the second sampling resistor are equal.

[0017] Preferably, the operational amplifier circuit includes a first operational amplifier, a second operational amplifier, a third operational amplifier, and first to twelfth resistors; wherein: one end of the third resistor is the first input terminal of the operational amplifier circuit and is connected to the first output terminal of the leakage current extraction circuit; one end of the second resistor is the second input terminal of the operational amplifier circuit and is connected to the second output terminal of the leakage current extraction circuit; the input terminals of the operational amplifier circuit include the first input terminal and the second input terminal; the other end of the third resistor and one end of the seventh resistor are both connected to the positive input terminal of the second operational amplifier, and the other end of the seventh resistor is connected to the drive power supply ground; one end of the fourth resistor is connected to the drive power supply ground, and the other end of the fourth resistor and one end of the eighth resistor are both connected to the negative input terminal of the second operational amplifier, and the other end of the eighth resistor... One end of the tenth resistor is connected to the output of the second operational amplifier. The other end of the tenth resistor and one end of the twelfth resistor are both connected to the negative input of the third operational amplifier. The other end of the twelfth resistor is connected to the output of the third operational amplifier. The other end of the second resistor and one end of the sixth resistor are both connected to the negative input of the first operational amplifier. One end of the first resistor and one end of the fifth resistor are both connected to the positive input of the first operational amplifier. The other end of the first resistor is connected to the drive power ground. The other end of the fifth resistor is connected to the drive power ground. The other end of the sixth resistor and one end of the ninth resistor are both connected to the output of the first operational amplifier. The other end of the ninth resistor and one end of the eleventh resistor are both connected to the positive input of the third operational amplifier. The other end of the eleventh resistor is connected to the drive power ground.

[0018] Preferably, the resistance values ​​of the first to fourth resistors are equal, the resistance values ​​of the fifth to eighth resistors are equal, the resistance values ​​of the ninth and tenth resistors are equal, and the resistance values ​​of the eleventh and twelfth resistors are equal.

[0019] Preferably, the operational amplifier circuit outputs a DC voltage signal, which is proportional to the gate leakage current. Specifically, the DC voltage signal and the gate leakage current satisfy the following formula:

[0020]

[0021] in: It is a DC voltage signal; For differential amplification gain, and , The eleventh resistor, It is the ninth resistor; This is the primary amplification gain, and , The fifth resistor, The first resistor; The resistance value is used for calculation, and the resistance value used for calculation is equal to the resistance values ​​of the first sampling resistor and the second sampling resistor; This represents the gate leakage current.

[0022] To achieve the above objectives, this application also provides an online gate leakage current monitoring system for GaN power devices, applicable to the online gate leakage current monitoring method for GaN power devices as described above, comprising:

[0023] The average gate drive current extraction module is used to extract the average gate drive current, which is the average value of the instantaneous current flowing into or out of the gate of the GaN power device during a complete switching cycle.

[0024] The gate leakage current monitoring module is used to obtain the gate leakage current based on the average gate drive current, so as to perform online gate leakage current monitoring of GaN power devices.

[0025] Beneficial effects: The online gate leakage current monitoring method and system for GaN power devices of this application solves the core problems of insufficient resolution and inability to achieve early warning in traditional voltage detection methods by converting high-frequency transient gate current into its positive and negative DC components and using the difference between the two to accurately calculate the submicroampere gate leakage current. At the same time, the use of source series sampling and non-intrusive signal conditioning circuit avoids the introduction of switching and voltage regulation circuits in the gate drive loop, thereby eliminating interference to gate loop parasitic parameters and ensuring its feasibility and reliability in high-frequency, high-sensitivity GaN power devices. Attached Figure Description

[0026] 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.

[0027] Figure 1 A flowchart illustrating an online gate leakage current monitoring method for GaN power devices provided in an embodiment of this application;

[0028] Figure 2 The GaN power device provided in the embodiments of this application and The waveform;

[0029] Figure 3 A topology diagram of the detection circuit provided in the embodiments of this application;

[0030] Figure 4The simulation results provided for the embodiments of this application;

[0031] Figure 5 This is a structural block diagram of an online gate leakage current monitoring system for GaN power devices provided in an embodiment of this application; in the figure: 10, average gate drive current extraction module; 20, gate leakage current monitoring module.

[0032] 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

[0033] 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.

[0034] 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.

[0035] Reference Figure 1 , Figure 1 This is a flowchart illustrating an online gate leakage current monitoring method for GaN power devices provided in an embodiment of this application.

[0036] like Figure 1 As shown, this embodiment discloses an online gate leakage current monitoring method for GaN power devices, including:

[0037] S1: Extract the average gate drive current, which is the average value of the instantaneous current flowing into or out of the gate of the GaN power device during a complete switching cycle.

[0038] Reference Figure 2 , Figure 2 The GaN power device provided in the embodiments of this application and The waveform.

[0039] like Figure 2As shown, the gate leakage current of gallium nitride (GaN) devices is within a few hundred microamps, while the instantaneous gate drive current can reach several amperes. This is the challenge of identifying microamp-level currents under online conditions. Therefore, this embodiment proposes the concept of average gate drive current, which refers to the instantaneous current flowing into or out of the gate of the power device during a complete switching cycle. The average value. Based on the current direction, this embodiment defines it as two key parameters.

[0040] Specifically, the average gate drive current includes a positive average gate drive current and a negative average gate drive current. The positive average gate drive current is the average value of the instantaneous current flowing into the gate of the GaN power device during a complete switching cycle, and the negative average gate drive current is the average value of the instantaneous current flowing out of the gate of the GaN power device during a complete switching cycle.

[0041] In the specific application of this embodiment: the forward average gate drive current mainly corresponds to the gate drive source's response to the gate capacitance during device turn-on. and The total charge during charging and the total charge during leakage current; the negative average gate drive current mainly corresponds to the total charge discharged by the gate capacitor through the drive circuit during the device turn-off process.

[0042] Specifically, the mathematical expression for the forward average gate drive current is:

[0043]

[0044] in: The calculated average gate drive current, For the switching cycle, This refers to the instantaneous current flowing into the gate of the GaN power device;

[0045] The mathematical expression for the negative average gate drive current is:

[0046]

[0047] in: The calculated negative average gate drive current, For the switching cycle, This refers to the instantaneous current flowing out of the gate of the GaN power device.

[0048] Based on the mathematical expressions for the forward average gate drive current and the negative average gate drive current, the mathematical definition of the average gate drive current is obtained, and its expression is:

[0049] (1)

[0050] For an ideal gallium nitride power device, its gate can be considered a pure capacitor network in steady state. Therefore, during one switching cycle, the total charge injected into the gate when turned on should be equal to the total charge released from the gate when turned off, i.e.:

[0051] (2)

[0052] However, in reality, an equivalent leakage resistance is formed between the gate and the source. This generates a continuous gate leakage current. This DC property It will be superimposed on the existing capacitive charging and discharging current: in the on state, Flowing out from the gate drive source, through To the source, it increased In the off state, the gate voltage is 0. constant.

[0053] Therefore, for a practical gallium nitride device, its key characteristics become:

[0054] (3)

[0055] Based on this change in key feature, gate leakage current was monitored in this embodiment.

[0056] S2: Based on the average gate drive current, the high-frequency transient gate current is converted into its positive and negative DC components, and the gate leakage current is calculated using the difference between the two components to perform online gate leakage current monitoring of GaN power devices.

[0057] Specifically, the gate leakage current is obtained based on the average gate drive current. Specifically, the gate leakage current is equal to the difference between the positive average gate drive current and the negative average gate drive current.

[0058] In the specific application of this embodiment, the difference between the forward average gate drive current and the negative average gate drive current is exactly equal to the gate leakage current, and the corresponding mathematical expression is:

[0059] (4)

[0060] The core of the measurement principle in this embodiment lies in extracting and calculating the forward average gate drive current. and negative average gate drive current The difference directly and accurately yields the gate leakage current. This principle enables the measurement of weak DC signals that are difficult to measure directly. This is converted into DC signals with two relatively large values. and Differential measurements were used to achieve high resolution and high anti-interference capability.

[0061] Reference Figure 3 , Figure 3 This is a topology diagram of the detection circuit provided in an embodiment of this application.

[0062] like Figure 3 As shown, the detection circuit is divided into two parts. Simply put, one is the leakage current extraction part, which is responsible for converting the current signal into a voltage signal through diodes, resistors and capacitors. The other part is the operational amplifier circuit that subtracts and amplifies the voltage signal.

[0063] Specifically, such as Figure 3 As shown, the online gate leakage current monitoring method is based on a detection circuit, which includes a leakage current extraction circuit and an operational amplifier circuit. The input terminal of the leakage current extraction circuit is connected to the gate of the GaN power device, and the output terminal of the leakage current extraction circuit is connected to the input terminal of the operational amplifier circuit. The output terminal of the operational amplifier circuit outputs a DC voltage signal, which is proportional to the gate leakage current.

[0064] Specifically, such as Figure 3 As shown, the leakage current extraction circuit includes a first Schottky diode. Second Schottky diode First sampling resistor Second sampling resistor First capacitor Second capacitor Among them: the first Schottky diode The positive electrode and the second Schottky diode The negative terminal of the diode is connected to form the input terminal of the leakage current extraction circuit, which is then connected to the gate of the GaN power device; the first Schottky diode negative terminal, first sampling resistor one end and the first capacitor One end is connected; the second Schottky diode The positive terminal and the second sampling resistor One end and the second capacitor One end is connected; the first sampling resistor The other end, the first capacitor The other end, the second sampling resistor The other end and the second capacitor The other end of each diode is connected to the drive power supply ground; and: the first Schottky diode negative terminal, first sampling resistor one end and the first capacitor One end of the connection point forms the first output terminal of the leakage current extraction circuit, and the second Schottky diode The positive terminal and the second sampling resistor One end and the second capacitor One end of the connection point forms the second output terminal of the leakage current extraction circuit, and the output terminal of the leakage current extraction circuit includes the first output terminal and the second output terminal; and the first sampling resistor Second sampling resistor The resistance values ​​are equal, that is .

[0065] In the specific application of this embodiment, and Its function is to achieve current separation. and It is a sampling resistor. and A resistor is connected in parallel across the circuit to maintain voltage stability. To ensure the circuit's fast response time to accommodate the higher frequencies of the silicon nitride device, a Schottky diode is required due to its low junction capacitance and fast reverse recovery characteristics, which significantly reduce the transition time. Simultaneously, appropriate resistor and capacitor values ​​must be selected to ensure their time constants are large enough to guarantee voltage stability.

[0066] To detect Taking a branch road as an example, we will analyze its working process in detail.

[0067] At the moment the device is turned on, the gate driver chip outputs a positive voltage, driving a large transient current when the GaN device is turned on. A pulse flows into the gate, for and Charging. This current simultaneously flows through the sampling resistor. Current exist An instantaneous positive voltage drop is generated on it. Due to capacitance The voltage across the terminals cannot change abruptly; this instantaneous voltage... Will begin to target C f1 Charging. During this brief switching transient, The vast majority of it is used for Charge it to make its voltage Rapid rise.

[0068] When the device is stably turned on, the gate charging is complete, ideally... The capacitance is zero at this time. Through resistance Slow discharge, which makes the voltage There is a downward trend. However, in reality, gate leakage current exists. During this stage, it will continuously flow out from the driving source and pass through And will it be to Charging begins. This causes the voltage to... There is an upward trend. Ultimately, the voltage... The stable value is determined by the combined effect of the discharge current and the leakage charging current.

[0069] After several switching cycles of charging and discharging, the circuit reaches a dynamic equilibrium. In this equilibrium state, within a complete switching cycle, the current flowing into the capacitor... The average current flowing through the capacitor is equal to the average current flowing out. voltage at both ends It will remain at an almost constant DC level. Therefore, the capacitor The capacitance value must be chosen so that the circuit's time constant is much larger than the switching period. Based on the principle of charge balance, this stable DC voltage... The following relationship must be satisfied:

[0070] (5)

[0071] Similarly, in charge of testing On the branch, a stable DC voltage will be obtained:

[0072] (6)

[0073] This step is key to the implementation of the online gate leakage current monitoring method for GaN power devices in this embodiment. It effectively expands the time window for signal measurement, transforming the problem from "capturing minute differences at the nanosecond level" to "measuring stable differences in DC voltage", which greatly reduces the bandwidth requirements and noise sensitivity of the measurement circuit.

[0074] Specifically, such as Figure 3 As shown, the operational amplifier circuit includes a first operational amplifier. Second operational amplifier Third operational amplifier and the first resistor Up to the twelfth resistor Among them: the third resistor One end is the first input terminal of the operational amplifier circuit and is connected to the first output terminal of the leakage current extraction circuit. The second resistor... One end is the second input terminal of the operational amplifier circuit and is connected to the second output terminal of the leakage current extraction circuit. The input terminals of the operational amplifier circuit include the first input terminal and the second input terminal; the third resistor The other end and the seventh resistor One end of each is connected to the second operational amplifier Connect the positive input terminal to the seventh resistor. The other end is connected to the drive power ground; the fourth resistor One end is connected to the drive power ground, the fourth resistor The other end and the eighth resistor One end of each is connected to the second operational amplifier The negative input terminal is connected to the eighth resistor. The other end and the tenth resistor One end of each is connected to the second operational amplifier Connect the output terminal to the tenth resistor. The other end and the twelfth resistor One end is connected to the third operational amplifier The negative input terminal is connected to the twelfth resistor. The other end is connected to the third operational amplifier The output terminal is connected; the second resistor The other end and the sixth resistor One end of each is connected to the first operational amplifier The negative input terminal is connected to the first resistor. one end and the fifth resistor One end of each is connected to the first operational amplifier The positive input terminal is connected to the first resistor. The other end is connected to the drive power ground, the fifth resistor The other end is connected to the drive power ground, the sixth resistor The other end and the ninth resistor One end of each is connected to the first operational amplifier Connect the output terminal to the ninth resistor. The other end and the eleventh resistor One end is connected to the third operational amplifier Connect the positive input terminal to the eleventh resistor. The other end is connected to the drive power ground.

[0075] Specifically, the resistance values ​​of resistors one through four are equal; the resistance values ​​of resistors five through eight are equal; the resistance values ​​of resistors nine and ten are equal; and the resistance values ​​of resistors eleven and twelfth are equal. That is: , , , Therefore, the primary amplification gain Differential amplification gain Therefore, we can conclude that:

[0076] (7)

[0077] Combining equations (4) to (7), we get:

[0078] Specifically, the operational amplifier circuit outputs a DC voltage signal, which is proportional to the gate leakage current. Specifically, the DC voltage signal and the gate leakage current satisfy the following formula:

[0079]

[0080] in: It is a DC voltage signal; For differential amplification gain, and , The eleventh resistor, It is the ninth resistor; This is the primary amplification gain, and , The fifth resistor, The first resistor; The resistance value used for calculation is equal to the resistance values ​​of the first sampling resistor and the second sampling resistor, i.e. ; This represents the gate leakage current.

[0081] Equation (8) shows that the operational amplifier circuit outputs a signal similar to... proportional DC voltage signal This signal is regular and stable, which greatly reduces the dynamic range and requirements of subsequent acquisition circuits (such as ADCs), and facilitates integration into existing control systems.

[0082] The online gate leakage current monitoring method for GaN power devices disclosed in this embodiment is now verified by simulation.

[0083] The purpose of this embodiment is to monitor the gate leakage current of GaN power devices online. To this end, a small measurement platform was built on the LTspice platform to verify the theoretical analysis. The system parameters are shown in Table 1.

[0084] Table 1

[0085]

[0086] According to S2 analysis, the primary amplification gain Differential amplification gain .

[0087] Reference Figure 4 , Figure 4 The simulation results provided for the embodiments of this application.

[0088] Simulation results are as follows Figure 4 As shown, during the opening period After integration, the theoretical leakage current is 30.204uA. Wherein, At the moment of device turn-on and turn-off, there are large current spikes, which are the main factor interfering with online monitoring. It is 1.8121V, which can be obtained from formula (8). It is close to the theoretical value.

[0089] Reference Figure 5 , Figure 5 This is a structural block diagram of an online gate leakage current monitoring system for GaN power devices provided in an embodiment of this application.

[0090] like Figure 5 As shown, this embodiment also discloses an online gate leakage current monitoring system for GaN power devices, applicable to the online gate leakage current monitoring method for GaN power devices as described above, including:

[0091] The average gate drive current extraction module is used to extract the average gate drive current, which is the average value of the instantaneous current flowing into or out of the gate of the GaN power device during a complete switching cycle.

[0092] The gate leakage current monitoring module is used to obtain the gate leakage current based on the average gate drive current, so as to perform online gate leakage current monitoring of GaN power devices.

[0093] It should be noted that the online gate leakage current monitoring system for GaN power devices in this embodiment corresponds to the aforementioned online gate leakage current monitoring method for GaN power devices. Therefore, any content not specifically described in the online gate leakage current monitoring method for GaN power devices in this embodiment, including but not limited to functional definitions, working principles, and technical principles, can be referred to the description in the aforementioned online gate leakage current monitoring method for GaN power devices. This will not be elaborated upon further here.

[0094] In summary, the online gate leakage current monitoring method and system for GaN power devices of this embodiment have the following advantages and effects compared with the prior art:

[0095] This embodiment achieves early, high-resolution monitoring of gate degradation in GaN devices. By extracting and differentially calculating the positive and negative average gate drive currents, the monitoring resolution is improved to the sub-microamp level, effectively identifying minute leakage current changes in the early stages of gate oxide degradation, fundamentally solving the problem of lag in early warning methods. Simultaneously, the solution possesses excellent circuit compatibility and high-frequency adaptability. Its non-invasive design avoids introducing additional components into the sensitive gate loop, ensuring the high-speed switching performance of the GaN device. Furthermore, by converting high-frequency transient signals into DC signals for processing, the system's stability under high-frequency operation is ensured. In addition, this embodiment outputs a regular DC voltage signal, which can be achieved using only general-purpose discrete components, significantly reducing system cost and integration complexity.

[0096] 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 method for online gate leakage current monitoring of GaN power devices, characterized in that, include: Extract the average gate drive current, which is the average value of the instantaneous current flowing into or out of the gate of the GaN power device during a complete switching cycle. Based on the average gate drive current, the high-frequency transient gate current is converted into its positive and negative DC components, and the gate leakage current is calculated using the difference between the two components, so as to perform online gate leakage current monitoring of GaN power devices. The average gate drive current includes a positive average gate drive current and a negative average gate drive current. The positive average gate drive current is the average value of the instantaneous current flowing into the gate of the GaN power device during a complete switching cycle, and the negative average gate drive current is the average value of the instantaneous current flowing out of the gate of the GaN power device during a complete switching cycle. Based on the average gate drive current, the gate leakage current is obtained, specifically the gate leakage current is equal to the difference between the positive average gate drive current and the negative average gate drive current. The mathematical expression for the forward average gate drive current is: in: The calculated average gate drive current, For the switching cycle, This refers to the instantaneous current flowing into the gate of the GaN power device; The mathematical expression for the negative average gate drive current is: in: The calculated negative average gate drive current, For the switching cycle, This refers to the instantaneous current flowing out of the gate of the GaN power device.

2. The online gate leakage current monitoring method for GaN power devices according to claim 1, characterized in that, The online gate leakage current monitoring method is based on a detection circuit, which includes a leakage current extraction circuit and an operational amplifier circuit. The input terminal of the leakage current extraction circuit is connected to the gate of the GaN power device, and the output terminal of the leakage current extraction circuit is connected to the input terminal of the operational amplifier circuit. The output terminal of the operational amplifier circuit outputs a DC voltage signal, which is proportional to the gate leakage current.

3. The online gate leakage current monitoring method for GaN power devices according to claim 2, characterized in that, The leakage current extraction circuit includes a first Schottky diode, a second Schottky diode, a first sampling resistor, a second sampling resistor, a first capacitor, and a second capacitor. The anode of the first Schottky diode and the cathode of the second Schottky diode are connected to form the input terminal of the leakage current extraction circuit, which is connected to the gate of the GaN power device. The cathode of the first Schottky diode, one end of the first sampling resistor, and one end of the first capacitor are connected. The anode of the second Schottky diode, one end of the second sampling resistor, and one end of the second capacitor are connected. The other ends of the first sampling resistor, the first capacitor, the second sampling resistor, and the second capacitor are all connected to the drive power supply ground. The connection point between the cathode of the first Schottky diode, one end of the first sampling resistor, and one end of the first capacitor forms the first output terminal of the leakage current extraction circuit. The connection point between the anode of the second Schottky diode, one end of the second sampling resistor, and one end of the second capacitor forms the second output terminal of the leakage current extraction circuit. The output terminals of the leakage current extraction circuit include the first output terminal and the second output terminal. The resistance values ​​of the first sampling resistor and the second sampling resistor are equal.

4. The online gate leakage current monitoring method for GaN power devices according to claim 3, characterized in that, The operational amplifier circuit includes a first operational amplifier, a second operational amplifier, a third operational amplifier, and first to twelfth resistors; wherein: one end of the third resistor is the first input terminal of the operational amplifier circuit and is connected to the first output terminal of the leakage current extraction circuit; one end of the second resistor is the second input terminal of the operational amplifier circuit and is connected to the second output terminal of the leakage current extraction circuit; the input terminals of the operational amplifier circuit include the first input terminal and the second input terminal; the other ends of the third resistor and one end of the seventh resistor are both connected to the positive input terminal of the second operational amplifier; the other end of the seventh resistor is connected to the drive power supply ground; one end of the fourth resistor is connected to the drive power supply ground; the other ends of the fourth resistor and one end of the eighth resistor are both connected to the negative input terminal of the second operational amplifier; the other end of the eighth resistor and the twelfth resistor are connected to the negative input terminal of the twelfth resistor. One end of each resistor is connected to the output of the second operational amplifier. The other end of the tenth resistor and one end of the twelfth resistor are both connected to the negative input of the third operational amplifier. The other end of the twelfth resistor is connected to the output of the third operational amplifier. The other end of the second resistor and one end of the sixth resistor are both connected to the negative input of the first operational amplifier. One end of the first resistor and one end of the fifth resistor are both connected to the positive input of the first operational amplifier. The other end of the first resistor is connected to the drive power ground. The other end of the fifth resistor is connected to the drive power ground. The other end of the sixth resistor and one end of the ninth resistor are both connected to the output of the first operational amplifier. The other end of the ninth resistor and one end of the eleventh resistor are both connected to the positive input of the third operational amplifier. The other end of the eleventh resistor is connected to the drive power ground.

5. The online gate leakage current monitoring method for GaN power devices according to claim 4, characterized in that, The resistance values ​​of the first to fourth resistors are equal, the resistance values ​​of the fifth to eighth resistors are equal, the resistance values ​​of the ninth and tenth resistors are equal, and the resistance values ​​of the eleventh and twelfth resistors are equal.

6. The online gate leakage current monitoring method for GaN power devices according to claim 5, characterized in that, The operational amplifier circuit outputs a DC voltage signal, which is proportional to the gate leakage current. Specifically, the DC voltage signal and the gate leakage current satisfy the following formula: in: It is a DC voltage signal; For differential amplification gain, and , The eleventh resistor, It is the ninth resistor; This is the primary amplification gain, and , The fifth resistor, The first resistor; The resistance value is used for calculation, and the resistance value used for calculation is equal to the resistance values ​​of the first sampling resistor and the second sampling resistor; This represents the gate leakage current.

7. An online gate leakage current monitoring system for GaN power devices, applicable to the online gate leakage current monitoring method for GaN power devices as described in any one of claims 1 to 6, characterized in that, include: The average gate drive current extraction module is used to extract the average gate drive current, which is the average value of the instantaneous current flowing into or out of the gate of the GaN power device during a complete switching cycle. The gate leakage current monitoring module is used to obtain the gate leakage current based on the average gate drive current, so as to perform online gate leakage current monitoring of GaN power devices.

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