A method for detecting defects in wireless power transmission circuits of unmanned aerial vehicles

Abstract

The present application belongs to the technical field of drone status detection, specifically a method for detecting defects in a drone wireless power transmission circuit, including obtaining the triggering time t0 of each switch gate of a high-frequency converter; obtaining the start time t1 of the decrease of the collector-emitter voltage of each switch of the high-frequency converter; judging whether the difference Δt between the triggering time t0 and the decrease time t1 of each switch of the high-frequency converter exceeds a preset threshold; if not, the switch is in a normal state and can continue to operate; if so, classify the time difference Δt through a defect recognition model, and extract the switch that has aged and caused an abnormality. The present application classifies the core components of the drone wireless power transmission circuit, namely, each switch of the high-frequency converter, using the time difference Δt through a defect recognition model, extracts the switch that has aged and caused an abnormality, and replaces it in time, thereby avoiding affecting the wireless network relay service, which helps to improve the reliability of drone operation in the field of wireless network relay.

Description

Technical Field

[0001] The present application belongs to the technical field of drone status detection, and more specifically, to a method for detecting defects in a drone wireless power transmission circuit. Background Art

[0002] In recent years, the rapid development and application of drone technology has provided new solutions for wireless network relay, etc. However, due to the limitations of its small load and short endurance, there are bottlenecks in further development. To overcome the above difficulties, the flexible and efficient charging of drones through wireless power transfer (WPT) technology has broad development prospects. Among them, improving power density and adapting to the development needs of miniaturization and lightweight of drones are the key. Therefore, exploring the technical realization of high-power density wireless power transmission circuits for drones at higher frequencies has become the mainstream. At present, the operating frequency of wireless power transmission circuits in this field has been increased to 1MHz, which leads to the long-term operation of the switch tube (IGBT or MOSFET device) of the high-frequency converter, which constitutes the core component of the wireless power transmission circuit, under high switching frequency and thermal stress conditions, and the aging process is accelerated, and the probability of defects and failures increases. In this form, IGBT or MOSFET device defect identification technology came into being, but the physical aging of IGBT or MOSFET devices gives very few external characterization parameters, resulting in the dilemma of lack of reliability information, which to a certain extent restricts the research on the reliability degradation of IGBT or MOSFET devices in operation. Summary of the invention

[0003] To achieve the above purpose, the technical solution adopted in this application is: to provide a method for detecting defects in the wireless power transmission circuit of a drone, comprising the following steps:

[0004] Step 1: Obtain the triggering time of each switch gate of the high-frequency converter ;

[0005] Step 2: Obtain the start time of the collector-emitter voltage drop of each switch tube of the high-frequency converter ;

[0006] Step 3: Determine the triggering time of each switch tube of the high-frequency converter and the falling time The difference Whether the change relative to the initial value exceeds the preset threshold; if not, the switch tube is in normal state and can continue to operate; if so, the time difference The defect recognition model is used for classification to extract the switch tubes with abnormalities caused by aging.

[0007] Optionally, in step 3, the preset threshold is: time difference The change is 20% of the initial value.

[0008] Optionally, the switch tube of the high-frequency converter includes an IGBT device or a MOSFET device.

[0009] Optionally, the IGBT device includes a Darlington structure consisting of a bipolar junction transistor (BJT) and an insulated gate field effect transistor (MOSFET).

[0010] Optionally, in step 3, the defect recognition model is used to identify the defect according to the time difference Classify the switch tube defects of high-frequency converters;

[0011] The IGBT device includes a gate G, an emitter E and a collector C. The gate G and the emitter E are connected by a capacitor. The gate G and emitter E are coupled through a capacitor Coupling, the gate G and collector C are connected by a series capacitor and capacitor Coupling, the emitter EE and collector C are connected by a capacitor Coupling, the emitter E and collector C are connected by a capacitor Coupling, the gate G and collector C are connected by a capacitor and capacitor Coupling, the gate G and collector C are also connected by a resistor coupling.

[0012] Optionally, the switching characteristics of the switch tube of the high-frequency converter are affected by the following parameters, as shown in formulas (1) to (9):

[0013] (1)

[0014] (2)

[0015] (3)

[0016] (4)

[0017] (5)

[0018] (6)

[0019] (7)

[0020] (8)

[0021] (9)

[0022] In the formula, is the excess carriers in the total base region, is the dielectric constant of silicon, is the charge of the electron, is the width of the quasi-neutral base region, is the doping concentration of the base region, is the electron mobility, is the mobility of holes, is the scattering mobility of the carriers, is the effective area of ​​the chip, is the overlapping area between the gate and drain of the MOFSET part in the IGBT device, is the bipolar diffusion length, is the collector-emitter voltage of the IGBT device, is the gate threshold voltage of the IGBT device.

[0023] Optionally, during the transient state of the turn-on, the gate-collector equivalent capacitance of the IGBT device Collector-emitter voltage The change of has different values, as shown in formula (10):

[0024] (10)

[0025] Optionally, in Period: From At the beginning of the moment, the gate voltage of the IGBT device Under the stimulation of the driving circuit voltage, it gradually rises until When the gate threshold voltage is reached .

[0026] Optionally, when the gate-collector equivalent capacitance When and is a constant, the response of the gate voltage and current exhibits the characteristics of a steady-state second-order circuit, as shown in formula (11):

[0027] (11)

[0028] In formula (11), is the gate drive circuit voltage, is the gate drive circuit resistance, both are constants, As the IGBT device ages, the time difference is established by formula (11) The corresponding relationship between the defects of various switching tubes in the high-frequency converter in the wireless power transmission circuit of the UAV.

[0029] The present application provides a method for detecting defects in a wireless power transmission circuit of a drone, wherein the core components of the wireless power transmission circuit of the drone, namely, the switch tubes of the high-frequency converter, are obtained by using a time difference Through classification by the defect recognition model, the switch tubes that have aged and caused abnormalities are extracted and replaced in time to avoid affecting the wireless network relay service. This solves the common problems of the existing technology, such as the lack of significant feature quantities during failure, susceptibility to on-site noise interference, poor sensitivity and low accuracy. It prevents the burning of the switch tubes, which may cause failures in the wireless power transmission circuit and wireless network interruption during operation, and helps to improve the reliability of UAV operation in the field of wireless network relay. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0031] Figure 1 A flow chart of the method for detecting defects in wireless power transmission circuits of drones for this application;

[0032] Figure 2 This is an example diagram of defects of a switch tube (IGBT or MOSFET device) in the high-frequency converter in this application;

[0033] Figure 3 This is a schematic diagram of the IGBT device turn-on process;

[0034] Figure 4 It is the equivalent circuit diagram of IGBT device. DETAILED DESCRIPTION

[0035] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0036] A method for detecting defects in a wireless power transmission circuit of a drone provided in an embodiment of the present application is now described.

[0037] See also Figure 1 , a method for detecting defects in a wireless power transmission circuit of a drone, comprising the following steps:

[0038] Step 1: Obtain the triggering time of each switch gate of the high-frequency converter .

[0039] Obtain the triggering moment of each switch gate of the high-frequency converter in the UAV wireless power transmission circuit .

[0040] Step 2: Obtain the start time of the collector-emitter voltage drop of each switch tube of the high-frequency converter .

[0041] Obtain the collector-emitter (or source-drain) voltage of each switch tube of the high-frequency converter in the wireless power transmission circuit of the drone Start of descent .

[0042] Step 3: Determine the triggering time of each switch tube of the high-frequency converter and the falling time The difference Whether the change exceeds the preset threshold; if not, the switch tube is in normal state and can continue to operate; if so, the time difference The defect recognition model is used for classification to extract the switch tubes with abnormalities caused by aging.

[0043] According to the obtained UAV wireless power transmission circuit, the switch tube of the high-frequency converter is triggered from the moment To the collector-emitter (or source-drain) voltage Start of descent The time difference between ) changes, the defect recognition model is used to determine whether it exceeds the preset threshold, as follows Figure 3 shown. Figure 3 In this paper, IGBT devices are used as an example. The vertical axis represents the collector-emitter (or source-drain) voltage. , the horizontal axis represents time.

[0044] Preferably, the preset threshold is: time difference The change is 20% of the initial value.

[0045] Step 4: Defect identification is completed.

[0046] Furthermore, in step 3, the defect recognition model is based on the time difference The corresponding relationship between the parameter and the state target value (i.e., the switch tube defect) is used to The defects of the switch tube of the high-frequency converter are classified; the switch tube of the high-frequency converter includes an IGBT device or a MOSFET device, wherein the switch tube IGBT device of the high-frequency converter includes a Darlington structure composed of a bipolar transistor BJT and an insulated gate field effect transistor MOSFET, etc. The specific structure of the switch tube IGBT device of the high-frequency converter is described as an example:

[0047] The switch tube IGBT device of the high-frequency converter includes a gate G, an emitter E and a collector C. The gate G and the emitter E are connected by a capacitor. The gate G and emitter E are coupled through a capacitor Coupling, the gate G and collector C are connected by a series capacitor and capacitor Coupling, the emitter EE and collector C are connected by a capacitor Coupling, the emitter E and collector C are connected by a capacitor Coupling, the gate G and collector C are connected by a capacitor and capacitor Coupling, the gate G and collector C are also connected by a resistor Coupling, see Figure 4 .

[0048] In addition, MOSFET devices can be regarded as components of IGBT devices and will not be described in detail.

[0049] capacitance ,capacitance ,capacitance ,capacitance ,capacitance ,capacitance ,capacitance ,capacitance ,resistance These are all stray parameters of IGBT devices. and capacitor Has nonlinear characteristics.

[0050] In summary, the switching characteristics of IGBT devices are affected by the following parameters, as shown in formulas (1) to (9):

[0051] (1)

[0052] (2)

[0053] (3)

[0054] (4)

[0055] (5)

[0056] (6)

[0057] (7)

[0058] (8)

[0059] (9)

[0060] In the formula, is the excess carriers in the total base region (C), is the dielectric constant of silicon (1.05×1012F / cm), is the charge of the electron (1.6×10-19C), is the width of the quasi-neutral base region (μm), is the doping concentration of the base region (cm-3), is the electron mobility (cm2 / V·s), is the hole mobility (cm2 / V·s), is the scattering mobility of the carriers (cm2 / V·s), is the effective area of ​​the chip, is the overlapping area between the gate and drain of the MOFSET part in the IGBT device, is the bipolar diffusion length (μm), is the collector-emitter voltage of the IGBT device, is the gate threshold voltage of the IGBT device. and capacitor The nonlinearity increases the complexity of the IGBT transient process.

[0061] From formulas (1) to (9), we can see that the overlapping depletion layer capacitance between the gate and the drain in the gate equivalent circuit is Collector-emitter voltage During the transient process of turning on, the gate-collector equivalent capacitance of the IGBT device Will be accompanied by collector-emitter voltage The change of has different values, as shown in formula (10):

[0062] (10)

[0063] exist Period: From At the beginning of the moment, the gate voltage of the IGBT device Under the stimulation of the driving circuit voltage, it gradually rises until When the gate threshold voltage is reached .

[0064] When period, , so the IGBT device is still in the off state, its collector terminal voltage and current do not change, and , from formula (4) and formula (10), we know that the gate-collector equivalent capacitance is and is a constant, the response of the gate voltage and current shows the characteristics of a steady-state second-order circuit, as shown in formula (11):

[0065] (11)

[0066] In formula (11), is the gate drive circuit voltage, is the gate drive circuit resistance, which is a constant and has nothing to do with the aging of the IGBT device. will change with the aging progress of the IGBT device. Formula (11) establishes the time difference The corresponding relationship between the defects of various switching tubes in the high-frequency converter in the wireless power transmission circuit of the UAV.

[0067] Take the detection of an IGBT device in the high-frequency converter, a core component in the WPT circuit of a drone, as an example. The specific steps are as follows:

[0068] Step 1: Obtain the triggering time of an IGBT device in the high-frequency converter, the core component of the drone WPT circuit .

[0069] Step 2: Obtain the collector-emitter voltage of an IGBT device in the high-frequency converter, the core component of the drone WPT circuit Start of descent .

[0070] Step 3: Obtain the time difference of a certain IGBT device in the high-frequency converter, a core component in the drone WPT circuit, before the defect occurs The circuit is 0.87us;

[0071] Obtain the time difference of a certain IGBT device in the high-frequency converter, a core component in the UAV WPT circuit, after the defect occurs The circuit is 0.56us;

[0072] Obtain the time difference of a certain IGBT device in the high-frequency converter, the core component of the UAV WPT circuit The change is 38.75 and the device is defective.

[0073] Step 4: Defect identification is completed.

[0074] This application takes the IGBT or MOSFET device in the UAV WPT circuit as an example, see Figure 2 , from the trigger moment Collector-emitter voltage Start of descent The time difference between is a characterization parameter. Figure 1 , turn on the IGBT or MOSFET device trigger signal and send it to the timer circuit as the timing start time According to the switching mechanism of IGBT or MOSFET devices, in order to facilitate on-site implementation, the collector-emitter voltage Start of descent , which is equivalent to the collector-emitter current zero-crossing moment, is collected by the precision detection resistor and sent to the zero-crossing detection circuit for processing to generate a timing stop signal. The timer circuit will collect the time difference for the first time, that is, , as a normal reference value, is sent to the latch circuit for storage and sent to the comparator circuit when needed. After that, during the IGBT or MOSFET device opening process, the time difference is collected at a certain time interval, that is, , and send it to the comparator circuit for comparison with the normal reference value stored in the latch circuit. When the actual collected value is compared with the normal reference value and the deviation exceeds 20% (statistical conclusion), the comparator circuit sends an early warning signal and feeds it back to the driver board, indicating that the IGBT or MOSFET device has a defect and needs to be dealt with in time, such as replacement.

[0075] The present application provides a method for detecting defects in a wireless power transmission circuit of a drone, wherein the core components of the wireless power transmission circuit of the drone, namely, the switch tubes of the high-frequency converter, are obtained by using a time difference Through classification by the defect recognition model, the switch tubes that have aged and caused abnormalities are extracted and replaced in time to avoid affecting the wireless network relay service. This solves the common problems of the existing technology, such as the lack of significant feature quantities during failure, susceptibility to on-site noise interference, poor sensitivity and low accuracy. It prevents the burning of the switch tubes, which may cause failures in the wireless power transmission circuit and wireless network interruption during operation, and helps to improve the reliability of UAV operation in the field of wireless network relay.

[0076] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for detecting defects in wireless power transmission circuits of unmanned aerial vehicles, characterized in that: The following steps are involved: Step 1: Obtain the triggering time of each switch gate of the high-frequency converter ; Step 2: Obtain the start time of the collector-emitter voltage drop of each switch tube of the high-frequency converter ; Step 3: Determine the triggering time of each switch tube of the high-frequency converter and the falling time The difference Whether the change relative to the initial value exceeds the preset threshold; if not, the switch tube is in normal state and can continue to operate; if so, the time difference The defect recognition model is used to classify and extract the switch tubes that are abnormal due to aging; The switch tube of the high-frequency converter includes an IGBT device or a MOSFET device; IGBT devices include a Darlington structure consisting of a bipolar transistor BJT and an insulated gate field effect transistor MOSFET; In step three, the defect recognition model is used to classify the switching tube defects of the high-frequency converter according to the time difference. The timer circuit uses the time difference collected for the first time as the normal reference value and sends it to the latch circuit for storage. Thereafter, during the opening process of the IGBT or MOSFET device, the time difference is collected at a certain time interval. The comparator circuit is used to compare the collected time difference with the normal reference value stored in the latch circuit. When the deviation exceeds 20%, the comparator circuit sends a warning signal and feeds back to the driver board, indicating that the IGBT or MOSFET device has a defect and needs to be handled in time.

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