Non-contact antenna sensor for monitoring power electronic switching device

Abstract

The invention discloses a non-contact antenna sensor for monitoring a power electronic switching device. The non-contact antenna sensor comprises an annular antenna, an oscillating circuit and a detection circuit, the change of the current i of the tested power electronic switching device in the switching transient process causes the change of the surrounding magnetic field B, thereby causing the change of the planar magnetic flux phi of the loop antenna, and enabling the two ends of the loop antenna to generate induced electromotive force e. The oscillating circuit outputs oscillating voltage Vosc under the action of the induced electromotive force e; the detection circuit extracts the initial peak value Vp of the oscillation voltage Vosc and maintains the output voltage Vo of the oscillation voltage Vosc at the initial peak value Vp state for a preset time; under the conditions that a commutation loop is not inserted and no contact is generated with a tested system, information of the current change rate of the power electronic switching device at the switching moment is captured, so that state evaluation is carried out on the power electronic switching device, and the device has the advantages of low cost, light size, high integration level, convenience in use and the like.

Description

Technical Field

[0001] This invention relates to the field of monitoring power electronic switching devices, and more specifically to a non-contact antenna sensor for monitoring power electronic switching devices. Background Technology

[0002] Power electronic switching devices, such as SiC MOSFETs and IGBTs, are widely used in electric vehicle drives, aerospace, and new energy power generation due to their high temperature resistance, voltage resistance, high power density, and high operating frequency. However, the harsh electromagnetic environment in which power electronic switching devices operate makes them one of the most vulnerable components in a system. During long-term operation, various stresses can lead to structural aging, chip packaging degradation, and changes in static and dynamic parameters, thereby affecting their electrical performance and causing circuit instability, operational failures, and even catastrophic accidents. Therefore, improving the operational reliability of power electronic switching devices through condition monitoring is of great significance.

[0003] Currently, the condition monitoring methods for power electronic switching devices can be broadly classified into two categories: contact-based and non-contact-based. Contact-based monitoring methods primarily monitor the health status of power electronic switching devices by directly measuring parameters such as gate leakage current, Miller plateau voltage, gate threshold voltage, on-resistance, and voltage change rate dv / dt. This method requires direct contact measurement of the gate voltage or transistor voltage drop, which may introduce safety hazards and affect the long-term reliable operation of the system.

[0004] Non-contact monitoring methods typically use non-contact sensors such as Rogowski coils and flexible current probes to monitor the status of power electronic switching devices online. (Journal literature:) "Q. Zhang, G. Lu and P. Zhang. A High-Sensitivity Online Junction Temperature Monitoring Method for SiC MOSFET Based on the Turn-on Drain–Source Current Overshoot. IEEE Trans. Power Electron., vol. 37, no. 12, pp.15505-15516, Dec. 2022." This paper demonstrates the monitoring of the junction temperature state of SiC MOSFETs by measuring the overshoot of the drain current during turn-on using a commercial current probe. The journal article "J. Kang, A. Zhu, Y. Chen, H. Luo, L. Yao and Z. Xin. An Online Gate Oxide Degradation Monitoring Method for SiCMOSFET with Contactless PCB Rogowski Coil Approach. IEEE Trans. PowerElectr., vol. 38, no. 8, pp. 9673-9684, Aug." is also relevant. 2023. This method utilizes a PCB Rogowski coil to measure the current change rate di / dt of a SiC MOSFET and assesses the gate oxide degradation degree based on the change in di / dt. However, to measure the current signal of power electronic switching devices, the current sensor (Rogowski coil or flexible current probe) must be installed in the converter commutation circuit, which easily increases the length of the commutation circuit. To avoid excessive voltage overshoot induced by the parasitic inductance of the commutation circuit during high-speed switching of power electronic devices, leading to device breakdown, the length of the commutation circuit is often strictly limited in practical systems.

[0005] Furthermore, flexible current probes are also expensive. Therefore, existing non-contact sensors used in non-contact monitoring generally suffer from low integration density, poor installation flexibility, and high operating costs, making it difficult to meet the needs of the high-frequency and high-power-density development of power electronic switching devices.

[0006] To further improve the safety and ease of monitoring the status of power electronic switching devices, the literature "Li Wei, Du Mingxing. Monitoring method of gate oxide degradation status of SiC MOSFET based on EMR signal [J]. Journal of Tianjin University of Technology, 2025, 41(02): 57-64" uses a near-field probe to measure the electromagnetic radiation signal of SiC MOSFET and analyzes the change in drain current rate of change through a spectrum analyzer as a host computer to achieve gate oxide status monitoring of SiC MOSFET. Although the near-field probe can measure the changes in the spatial electromagnetic field generated by power electronic switching devices without being inserted into the commutation circuit, it requires large and expensive auxiliary equipment such as a spectrum analyzer, which is difficult to meet the needs of online monitoring of the status of power electronic switching devices.

[0007] Therefore, the applicant hopes to find a technical solution to address the above technical problems. Summary of the Invention

[0008] In view of this, the purpose of the present invention is to provide a non-contact antenna sensor for monitoring power electronic switching devices. It utilizes the electromagnetic field induction effect caused by the power electronic switching device during the switching transient process to capture the current change rate di / dt of the power electronic switching device at the switching moment without inserting into the commutation circuit and without making any contact with the system under test. This allows for state assessment of the power electronic switching device and has the advantages of low cost, light size, high integration, and ease of use.

[0009] The technical solution adopted in this invention is as follows:

[0010] A non-contact antenna sensor for monitoring power electronic switching devices includes a loop antenna located near the power electronic switching device under test, an oscillation circuit connected to both ends of the loop antenna, and a detection circuit connected to the output of the oscillation circuit. During the switching transient process of the power electronic switching device under test, the change in current *i* causes a change in the surrounding magnetic field *B*, which in turn causes a change in the planar magnetic flux *Φ* of the loop antenna, resulting in an induced electromotive force *e* at both ends of the loop antenna. Under the action of this induced electromotive force *e*, the oscillation circuit outputs an oscillation voltage *V*. osc Its initial peak value V p The current change rate di / dt of the tested power electronic switching device during the switching transient process is directly proportional to the current change rate di / dt; the detection circuit extracts the oscillation voltage V. osc initial peak value V p and its output voltage V o Maintain at the initial peak V p Status until preset time.

[0011] Preferably, the proportional relationship between the induced electromotive force e and the rate of change of current di / dt is as follows:

[0012] ;

[0013] ;

[0014] Where L is the coupling coefficient of the loop antenna; N is the number of turns of the loop antenna; λ m denoted as ρ, where ρ is the permeability of the loop antenna; A is the effective area of ​​the loop antenna; l is the distance from the loop antenna to the power electronic switching device under test; and μ0 is the permeability of free space.

[0015] Preferably, the oscillation circuit is an RLC oscillation circuit, including a resistor R. p Inductor L p Capacitor C p Composition; wherein, the inductor L p Connected to one end of the loop antenna and resistor R p Between them, the other end of the loop antenna is grounded; the resistor R p The output terminal and capacitor C p One of the electrical terminals is connected, capacitor C p The other electrode of the capacitor is grounded; the capacitor C p The two terminals of the electrode are respectively connected to the detection circuit to input the oscillation voltage V into the detection circuit. osc .

[0016] Preferably, the oscillation period T of the oscillation circuit is not greater than twice the switching time t. sw Under the condition that the oscillation voltage V osc initial peak value V p It appears at time T / 2 and is directly proportional to the rate of change of current di / dt of the tested power electronic switching device during the switching transient process; wherein, the switching time t sw This refers to the power electronic switching device under test where the current rises from 0 to the load current i. L The turn-on time or from the load current i L The shutdown time drops to 0.

[0017] Preferably, the oscillation voltage V osc initial peak value V p The direct proportional relationship with the rate of change of current di / dt is as follows:

[0018] ;

[0019] Where δ is the attenuation coefficient of the oscillating circuit, and ω is the oscillation frequency of the oscillating circuit; This represents the direct proportion

[0020] The prerequisite for the correspondence is that the oscillation period T of the oscillation circuit is not greater than twice the switching time t. sw .

[0021] Preferably, the formula for calculating the attenuation coefficient δ of the oscillation circuit is as follows:

[0022] ;

[0023] The formula for calculating the oscillation frequency ω of the oscillation circuit is as follows:

[0024] ;

[0025] The formula for calculating the oscillation period T of the oscillation circuit is as follows:

[0026] .

[0027] Preferably, the detection circuit includes an envelope detection circuit unit, a comparison circuit unit, a discharge circuit unit, and a peak maintenance circuit unit; wherein,

[0028] Oscillation voltage V osc After being amplified by the amplifier, the signals are input to the envelope detection circuit unit and the peak sustaining circuit unit, respectively.

[0029] The peak sustaining circuit unit captures the oscillation voltage V. osc initial peak value V p And the output voltage V of the detection circuit o Maintain at the initial peak V p state;

[0030] The oscillation voltage V is transmitted through the envelope detection circuit unit. osc Converted to envelope voltage V env This is input to the comparator circuit unit;

[0031] The envelope voltage V is measured by the comparison circuit unit. env With threshold voltage V TH When comparing, when the envelope voltage V env Greater than the threshold voltage V TH At that time, the comparator circuit unit output voltage V com A high level indicates a high voltage level; conversely, a low level indicates a low voltage level. The comparator circuit unit outputs a voltage V. com This is a low level;

[0032] The output voltage V of the comparator circuit unit com The input is given to the discharge circuit unit, which outputs the voltage V based on the comparator circuit unit. com The high and low level states are used to determine its output voltage V. dis The high and low level states of the signal;

[0033] The output voltage V of the discharge circuit unit disA signal is input to the peak sustain circuit unit, selectively turning on the peak sustain electronic switch Q of the peak sustain circuit unit. k This allows the peak value to be maintained by the electronic switch Q. k Before the power electronic switching device under test undergoes its next switching transient, the holding capacitor C is adjusted. k The discharge of the capacitor C sets its voltage to zero to prevent the capacitor from being held in place. k The residual voltage affects the next measurement, thus achieving the purpose of continuous multiple measurements.

[0034] Preferably, the discharge circuit unit includes an external capacitor C connected to it. x and resistance R x A steady-state trigger; the peak sustaining circuit unit includes a rectifier diode and a sustaining capacitor C. k and peak sustaining electronic switch Q k ;in,

[0035] The comparator circuit unit outputs a voltage V. com After the input is given to the steady-state trigger, when the comparator circuit unit outputs voltage V com When the voltage is low, the steady-state trigger sets its output voltage V. dis The signal is set to high level, turning on the peak sustaining electronic switch Q. k Connect the external capacitor C between the current input pin of the steady-state trigger and the external capacitor pin. x The external capacitor C x The other branch is connected to resistor R x The resistor pin is then connected; the output voltage V of the discharge circuit unit. dis High-level duration t of the signal d Due to external capacitor C x and resistance R x Decide;

[0036] The peak sustaining electronic switch Q k The output voltage V of the drive electrode connected to the discharge circuit unit dis The signal is connected to the other two terminals of the sustaining capacitor C. k Between the positive and negative terminals, the holding capacitor C k The negative terminal is grounded, and a first rectifier diode and a second rectifier diode are connected between it and the positive terminal respectively to achieve voltage regulation.

[0037] The oscillation voltage V after amplification by the amplifier osc Connect the connection point between the first rectifier diode and the second rectifier diode;

[0038] The sustaining capacitor C kThe positive and negative voltages are used as the output voltage V of the peak sustaining circuit unit. o ;

[0039] Among them, the initial peak value V p The capture process is as follows:

[0040] Peak sustaining electronic switch Q k The oscillation voltage V remains in the off state during this process. osc During the rise from 0, the amplifier output and the holding capacitor C k The second rectifier diode between the positive and negative terminals is at the oscillation voltage V. osc Under the action of , it conducts and maintains the capacitor C. k Charging; when the oscillation voltage V osc Rise to the initial peak V p At that time, maintain capacitor C k The voltage across the terminals reaches the initial peak value V p ; at the oscillation voltage V osc After the voltage drops, the second rectifier diode is reverse-biased and cuts off, maintaining capacitor C. k The voltage across the terminals remains at the initial peak value V. p level.

[0041] Preferably, the envelope detector circuit unit includes a rectifier diode and a resistor R. env and capacitor C env The filter circuit consists of a voltage comparator; the comparison circuit unit includes a voltage comparator; wherein,

[0042] The resistor R env The two ends of the capacitor C env The positive and negative terminals are connected, and the capacitor C env The negative terminal is grounded, and a third rectifier diode and a fourth rectifier diode are connected between it and the positive terminal respectively;

[0043] The oscillation voltage V after amplification by the amplifier osc Connect the connection point between the third rectifier diode and the fourth rectifier diode;

[0044] The resistor R env The positive output terminal is connected to the positive input terminal of the voltage comparator, and the threshold voltage V TH As the negative input signal of the voltage comparator;

[0045] The output of the voltage comparator is connected to the discharge circuit unit to convert the output voltage V of the comparator unit into voltage V. com Input to the discharge circuit unit.

[0046] Preferably, an MCU is used to capture the output voltage V of the peak sustaining circuit unit.o The preset time is not less than 10 ns.

[0047] It should be noted that the phrase "proportional to the rate of change of current di / dt of the power electronic switching device under test during the switching transient process" mentioned in the entire application includes an approximate proportional relationship, and can be used for online monitoring of the rate of change of current di / dt.

[0048] The main advantages of this application are as follows: This application proposes a non-contact antenna sensor for monitoring power electronic switching devices. This sensor utilizes the electromagnetic field induction (equivalent to electromagnetic radiation) effect caused by the power electronic switching device during the switching transient process to capture the current change rate di / dt of the power electronic switching device at the switching moment without inserting into the commutation circuit and without making any contact with the system under test, thereby performing state assessment of the power electronic switching device. It also has the advantages of low cost, light size, high integration, and convenient use.

[0049] Compared to contact-based condition monitoring methods, the sensor provided in this application can acquire information on the rate of change of current in power electronic devices during switching without any contact with the monitored system, thus improving the safety of condition monitoring. Compared to existing non-contact sensors using Rogowski coils and flexible current probes, the sensor provided in this application can acquire information on the rate of change of current di / dt of power electronic switching devices during switching transients without inserting into the commutation circuit, avoiding device breakdown caused by voltage overshoot due to excessive parasitic inductance in the commutation circuit during rapid switching, significantly improving the safety of condition monitoring. Compared to near-field probe condition monitoring, the sensor provided in this application converts the rate of change of current di / dt of power electronic switching devices during switching transients received by the loop antenna into an output level signal that is proportional to (or approximately proportional to) it through an oscillation circuit and a detection circuit, reducing the size, circuit complexity, and cost of the condition monitoring equipment, making it very suitable as an online condition monitoring device for power electronic switching devices. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of the principle circuit of a non-contact antenna sensor used for monitoring power electronic switching devices according to a specific embodiment of this application;

[0051] Figure 2 This is a schematic diagram of the working process of a non-contact antenna sensor used for monitoring power electronic switching devices according to a specific embodiment of this application;

[0052] Figure 3 This is a waveform diagram of the current and its rate of change during the turn-on process of the power electronic switching device according to a specific embodiment of this application; wherein, Figure 3 a) is a waveform diagram of the current i during the turn-on process of a power electronic switching device. Figure 3 b) is a waveform diagram of the current change rate di / dt of the power electronic switching device during the turn-on process;

[0053] Figure 4 This is a schematic diagram of the current of the power electronic switching device during the turn-on process according to a specific embodiment of this application;

[0054] Figure 5 This is a circuit diagram of a non-contact antenna sensor based on SiC MOSFET as the power electronic switching device under test in a specific embodiment of this application;

[0055] Figure 6 yes Figure 5 A picture of the actual product (a ruler is shown on the bottom of the product).

[0056] Figure 7 yes Figure 5 Waveforms of various voltage signals during operation;

[0057] Figure 8 This is a schematic diagram of the principle circuit of the Buck converter test platform built in a specific embodiment of this application;

[0058] Figure 9 yes Figure 8 The waveforms of various signals at the turn-on time of the SiC MOSFET under different gate resistance test conditions are shown in the figure. Figure 9 a) Waveforms of the drain current i of the SiC MOSFET under different gate resistances Rg. Figure 9 b) The oscillation voltage V under different gate resistances Rg. osc initial peak value V p waveform diagram, Figure 9 c) The output voltage V of the detection circuit under different gate resistances Rg. o The waveform diagram (i.e., the sensor output provided in this embodiment);

[0059] Figure 10 yes Figure 9 The experimental results of the tested SiC MOSFET under different gate resistance test conditions under continuous turn-on test conditions are shown below. Figure 10 a) This shows the data changes in the drain current rate of change di / dt during multiple consecutive turn-on processes. Figure 10 b) The initial peak value V during multiple consecutive activation processes. p Data changes Figure 10 c) The output voltage V of the detection circuit during multiple consecutive turn-on processes. oThe data changes (i.e., the sensor output provided in this embodiment). Figure 10 d) The drain current change rate di / dt and initial peak value V under different gate resistance test conditions during multiple consecutive turn-on processes. p and the output voltage V of the detection circuit o The average value of the data. Detailed Implementation

[0060] Please refer to the above. Figure 1 and Figure 2 As shown, this embodiment proposes a non-contact antenna sensor for monitoring power electronic switching devices. It includes a loop antenna (consisting of one or more turns of a loop coil) located near the power electronic switching device under test (which can be a SiC MOSFET, IGBT, or other power electronic switching devices; this embodiment does not specifically limit its type), an oscillation circuit connected to both ends of the loop antenna, and a detection circuit connected to the output of the oscillation circuit. The change in current i (note that when the power electronic switching device under test is a SiC MOSFET or IGBT, this current i refers to the drain current) caused by the change in the surrounding magnetic field B (i.e., the change in the corresponding current i) during the switching transient process (i.e., the turn-on or turn-off process) of the power electronic switching device under test causes a change in the surrounding magnetic field B (i.e., the corresponding current i). Figure 2 The relationship shown is: "The change in current i during the switching transient process of a power electronic switching device causes a change in the surrounding magnetic field B". This, in turn, causes a change in the planar magnetic flux Φ of the loop antenna (i.e., the corresponding...). Figure 2 The statement "Changes in the spatial magnetic field will cause changes in the planar magnetic flux Φ of the loop antenna" indicates the following relationship: This induces an electromotive force e at both ends of the loop antenna (i.e., the corresponding...). Figure 2 The relationship shown is: "The change in magnetic flux Φ will induce an electromotive force e at both ends of the loop antenna". That is, the induced electromotive force e is directly proportional to the rate of change of current di / dt); the oscillating circuit outputs an oscillating voltage V under the action of this induced electromotive force e. osc Its initial peak value V p It is directly proportional to the rate of change of current di / dt of the tested power electronic switching device during the switching transient process (i.e., it is... Figure 2 The oscillation circuit shown outputs an oscillation voltage V under the action of electromotive force. osc Its initial peak value V p "It is approximately proportional to the average rate of change of drain current during the switching process," and the corresponding relationship is: The detection circuit extracts the oscillation voltage V. osc initial peak value V p and its output voltage V oMaintain at the initial peak V p The state is restored after a preset time, preferably not less than 10 ns; more preferably not less than 150 ms (i.e., ...). Figure 2 The "detection circuit extracts V" shown p And output V o Maintain at V p "Horizontal time period (preferably 150ms or more)" corresponds to the following relationship: Preferably, in this embodiment, an MCU (e.g., an STM32 series microcontroller) is used to capture the output voltage V of the peak sustain circuit unit. o (That is, the output voltage V of the detection circuit) o ).

[0061] Preferably, please see further details. Figure 3 As shown, in this embodiment, taking the turn-on process of a power electronic switching device as an example, the current i (also referred to as the switching device current i) rises at an approximately constant rate (see...). Figure 3 As described in a), the waveform of its current change rate di / dt is approximately a square wave (see...). Figure 3 (b) The rapid change of current i will cause a change in the surrounding magnetic field, which in turn will generate an induced electromotive force e(t) at both ends of the loop antenna located nearby, which is proportional to the rate of change of current di / dt (it should be noted that the turn-off process of power electronic switching devices is based on a similar principle as its turn-on process, the only difference being that the polarity of the rate of change of current di / dt and the induced electromotive force e during the turn-off process is opposite to that during the turn-on process).

[0062] In this embodiment, the proportional relationship between the induced electromotive force e and the rate of change of current di / dt is as follows:

[0063] ;

[0064] ;

[0065] Where L is the coupling coefficient of the loop antenna; N is the number of turns of the loop antenna; λ m denoted as ρ, where ρ is the permeability of the loop antenna; A is the effective area of ​​the loop antenna; l is the distance from the loop antenna to the power electronic switching device under test; and μ0 is the permeability of free space.

[0066] Preferably, in this embodiment, the oscillation circuit is an RLC oscillation circuit, including a resistor R. p Inductor L p Capacitor C p Composition; among which, inductor L p Connected to one end of the loop antenna and resistor R pBetween them, the other end of the loop antenna is grounded; resistor R p The output terminal and capacitor C p One of the electrical terminals is connected, capacitor C p The other electrode of the capacitor is grounded; capacitor C p The two terminals of the electrode are connected to the detection circuit to input the oscillation voltage V. osc .

[0067] Preferably, the oscillation period T of the oscillation circuit is not greater than twice the switching time t. sw Under these conditions, the oscillation voltage V osc initial peak value V p It appears at time T / 2 and is directly proportional to the rate of change of current di / dt of the tested power electronic switching device during the switching transient process; where the switching time t sw This refers to the power electronic switching device under test where the current rises from 0 to the load current i. L The turn-on time or from the load current i L The turn-off time drops to 0; taking the turn-on process as an example, the current of the tested power electronic switching device during the turn-on process is as follows: Figure 4 As shown, where t sw This refers to the current rising from 0 to the load current i. L The time; similarly, the turn-off and turn-on processes of power electronic switching devices follow a similar principle (t). sw This refers to the load current i L The off-time drops to 0), and its oscillation circuit outputs a voltage signal V. osc Its polarity is opposite to that of the opening process.

[0068] Preferably, in this embodiment, the oscillation voltage V osc initial peak value V p The direct proportional relationship with the rate of change of current di / dt is as follows:

[0069] ;

[0070] Where δ is the attenuation coefficient of the oscillating circuit, and ω is the oscillation frequency of the oscillating circuit; This represents the direct proportion

[0071] The prerequisite for the correspondence is that the oscillation period T of the oscillation circuit is not greater than twice the switching time t. sw .

[0072] Preferably, in this embodiment, the formula for calculating the attenuation coefficient δ of the oscillation circuit is as follows:

[0073] ;

[0074] The formula for calculating the oscillation frequency ω of an oscillating circuit is as follows:

[0075] ;

[0076] The formula for calculating the oscillation period T of an oscillating circuit is as follows:

[0077] .

[0078] To enable those skilled in the art to better understand the technical solutions of this invention, based on the above implementation schemes, the following specific embodiments will be proposed in conjunction with the accompanying drawings of the embodiments of this invention. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0079] Based on the above implementation scheme, this application specifically proposes a non-contact antenna sensor for monitoring power electronic switching devices. Please refer to [link to relevant documentation]. Figure 5 and Figure 6 As shown, it includes an oscillation circuit located at the power electronic switching device under test (specifically a SiC MOSFET) and connected to both ends of the loop antenna, and a detection circuit connected to the output of the oscillation circuit; wherein,

[0080] The detection circuit includes an envelope detector circuit unit (i.e., Figure 5 The marked "envelope circuit"), comparator circuit unit (i.e. Figure 5 The "comparator circuit" and the discharge circuit unit (i.e., the one marked as "comparator circuit") Figure 5 The marked "discharge circuit" and peak sustaining circuit unit (i.e. Figure 5 The marked "peak sustaining circuit"); oscillation voltage V osc After being amplified (in this embodiment, a THS4001 amplifier is specifically used, with an oscillation voltage V), osc The voltage V is amplified by inputting it to the positive input terminal of the amplifier, and then input to the envelope detector circuit unit and the peak sustain circuit unit respectively; the peak sustain circuit unit captures the oscillation voltage V. osc initial peak value V p And the output voltage V of the detection circuit o Maintain at the initial peak V p State; the oscillation voltage V is transmitted through the envelope detector circuit unit. osc Converted to envelope voltage V env The input is given to the comparator circuit unit; the comparator circuit unit then converts the envelope voltage V... env With threshold voltage V TH When comparing, when the envelope voltage Venv Greater than the threshold voltage V TH At that time, the comparator circuit unit output voltage V com A high level indicates a high voltage level; conversely, a low level indicates a low voltage level. The comparator circuit unit outputs a voltage V. com This indicates a low level; the output voltage V of the comparator circuit unit will be low. com The input is given to the discharge circuit unit, which outputs the voltage V based on the comparator circuit unit. com The high and low level states are used to determine its output voltage V. dis The high and low level states of the signal;

[0081] The output voltage V of the discharge circuit unit dis When a signal is input to the peak sustain circuit unit, the peak sustain electronic switch Q of the peak sustain circuit unit is selectively turned on. k This allows the peak value to be maintained by the electronic switch Q. k Before the power electronic switching device under test undergoes its next switching transient, the holding capacitor C is adjusted. k The discharge of the capacitor C sets its voltage to zero to prevent the capacitor from being held in place. k The residual voltage affects the next measurement, thus achieving the purpose of continuous multiple measurements.

[0082] It should be noted that, in this embodiment, the threshold voltage V TH There are two principles for setting it up: First, ensure the output voltage V of the detection circuit. o The value remains at the initial peak V. p The time should not be less than the preset time; please combine Figure 7 As shown, the output voltage V of the detection circuit o The duration depends on the envelope voltage V env During the descent process, the threshold voltage V TH At the intersection point, the comparator circuit unit will output a low level (falling edge), thereby triggering the discharge circuit unit to discharge its output voltage V. dis The signal is set to high level, causing the peak sustaining electronic switch Q to... k The conduction enables the holding capacitor C to be turned on. k Discharge will reduce the output voltage V of the detection circuit. o Set to zero, end the holding capacitor C k First, to maintain the state so that it can enter the next maintenance operation; second, to avoid the envelope voltage V env Accidental touches caused by minute perturbations in the threshold voltage V TH It should not be set too low; in actual implementation, those skilled in the art should set the threshold voltage V according to this setting principle. TH .

[0083] Preferably, in this embodiment, the discharge circuit unit includes an external capacitor C connected to it.x and resistance R x A steady-state trigger (specifically, a CD74HC123 steady-state trigger is used in this embodiment); the circuit unit includes a rectifier diode and a holding capacitor C. k and peak sustaining electronic switch Q k ;in,

[0084] Comparator circuit unit output voltage V com After the input is given to the steady-state trigger, when the comparator circuit unit outputs voltage V com When the voltage is low, the steady-state trigger sets its output voltage V. dis When the signal is set to high, the conduction peak sustains the electronic switch Q. k Connect an external capacitor C between the current input pin VCC of the steady-state trigger and the external capacitor pin 1RC. x External capacitor C x The other branch is connected to resistor R x The resistor pin 1C is then connected; in this embodiment, according to the official chip manual provided by the steady-state trigger manufacturer, the output voltage V of the discharge circuit unit is... dis High-level duration t of the signal d Due to external capacitor C x and resistance R x The decision, and its corresponding relationship, is: t d =0.45·C x ·R x Among them, the high-level duration t d The setting principle is: to ensure the stability of the holding capacitor C k Under the premise of complete discharge, maintain the high level for as long as possible, t. d The setting is small to avoid peak maintenance electronic switch Q k Excessive conduction time can affect subsequent continuous measurement work.

[0085] Peak sustaining electronic switch Q k The output voltage V of the drive electrode connected to the discharge circuit unit dis The signal is connected to the other two terminals of the sustaining capacitor C. k Between the positive and negative terminals, maintain capacitance C k The negative terminal is grounded, and a first rectifier diode and a second rectifier diode are connected between it and the positive terminal respectively to achieve voltage regulation; the oscillation voltage V after amplification by the amplifier osc Connect the junction between the first rectifier diode and the second rectifier diode; maintain capacitor C k The positive and negative voltages are used as the output voltage V of the peak sustaining circuit unit. o ;

[0086] In this embodiment, the initial peak value V p The capture process is as follows:

[0087] Peak sustaining electronic switch Q k The oscillation voltage V remains in the off state during this process. osc During the rise from 0, the amplifier output and the holding capacitor C k The second rectifier diode between the positive and negative terminals is at the oscillation voltage V. osc Under the action of , it conducts and maintains the capacitor C. k Charging; when the oscillation voltage V osc Rise to the initial peak V p At that time, maintain capacitor C k The voltage across the terminals reaches the initial peak value V p ; at the oscillation voltage V osc After the voltage drops, the second rectifier diode is reverse-biased and cuts off, maintaining capacitor C. k The voltage across the terminals remains at the initial peak value V. p level.

[0088] Preferably, in this embodiment, the envelope detector circuit unit includes a rectifier diode and a resistor R. env and capacitor C env The filter circuit is composed of a voltage comparator (in this embodiment, a voltage comparator of model TLV3201 is specifically used); wherein,

[0089] resistor R env The two ends of the capacitor C env The positive and negative terminals are connected, and the capacitor C env The negative terminal is grounded, and a third rectifier diode and a fourth rectifier diode are connected between it and the positive terminal respectively; the oscillation voltage V after amplification by the amplifier osc Connect the junction between the third and fourth rectifier diodes; resistor R env The positive output terminal is connected to the positive input terminal of the voltage comparator, and the threshold voltage V TH The signal serves as the negative input of the voltage comparator; the output of the voltage comparator is connected to the discharge circuit unit to convert the output voltage V of the comparator unit. com Input to the discharge circuit unit.

[0090] In this embodiment, during the operation of the tested SiC MOSFET, please refer to the waveform diagrams of the voltage signals mentioned above. Figure 7 As shown.

[0091] To further verify the feasibility and effectiveness of the non-contact antenna sensor proposed in this embodiment, this application also specifically constructs a 1200V / 30A SiC MOSFET Buck converter experimental platform based on this non-contact antenna sensor. For the principle circuit setup, please refer to [link to relevant documentation]. Figure 8 As shown in Table 1, the basic parameter settings of the converter experimental platform are as follows; the SiC MOSFET equipped on this platform is a 1200 V / 30A SiC MOSFET, which will be used with the non-contact antenna sensor (i.e., the one described above) as described above. Figure 8 The "antenna sensor" (marked) is installed near the SiC MOSFET. The converter experimental platform also includes a converter inductor L and a converter diode (i.e.,...). Figure 8 The markings "diode", converter capacitor C0, and converter load R load The converter is controlled by a TI TMS320F28335 DSP controller, and the SiC MOSFET has an adjustable gate resistor R. g To verify the online monitoring effect of this embodiment, a flexible current probe (CP9003S, bandwidth 30MHz) was used to measure the drain current of the SiC MOSFET. Figure 8 The "current sensor" marked on the label was used to measure the output signals of the flexible current probe and the non-contact antenna sensor provided in this embodiment. The parameter settings of the non-contact antenna sensor prototype in this embodiment are shown in Table 2.

[0092] Table 1. Main parameter settings of the SiC MOSFET Buck converter experimental platform in this embodiment.

[0093]

[0094] Table 2. Main parameter settings for the non-contact antenna sensor in this embodiment.

[0095]

[0096] Taking the turn-on process of the SiC MOSFET under test as an example, the performance of the antenna sensor is tested by adjusting the gate resistance R of the SiC MOSFET during the experiment. g The resistance value (specifically, six different gate resistors R are set) g , respectively: R g =6.2Ω, R g =8.2Ω, R g =11Ω, R g =13Ω, R g =15Ω, R g=18Ω, gate resistor R g The resistance gradually increases; the drain current change rate di / dt of the SiC MOSFET during the turn-on process is artificially altered; a double-pulse experiment is performed on the SiC MOSFET Buck converter experimental platform of this embodiment under the parameter settings shown in Tables 1 and 2, and the gate resistance R is measured. g Under certain conditions, the drain current i and oscillation voltage V of the SiC MOSFET osc and the output voltage V of the detection circuit o :

[0097] Please see Figure 9 As shown, where, Figure 9 a) Figure 9 b) and Figure 9 c) These correspond to different gate resistances R g Waveform of drain current i and oscillation voltage V of SiC MOSFET under certain conditions osc initial peak value V p (that is) Figure 9 b) The marked "oscillation voltage V" p The waveform diagram and the output voltage V of the detection circuit. o (that is) Figure 9 c) The waveform diagram of the "detection circuit output level V0" marked thereon; through Figure 9 This indicates that at the gate resistance R g As the resistance gradually increases, the rate of increase of the drain current i in the SiC MOSFET during turn-on gradually slows down, and the oscillation voltage V... osc initial peak value V p and the output voltage V of the detection circuit o It also decreases accordingly; and the detection circuit can detect the output voltage V. o The voltage V is maintained above 200ns without significant drop, thus enabling online capture of this output voltage V using widely used MCUs. o (Such as STM32 series microcontrollers), with a wide range of applications.

[0098] exist Figure 9 Based on the results shown, please refer to further... Figure 10 The figure shows the experimental results of the SiC MOSFET under test under different gate resistance conditions during continuous turn-on testing; among them, Figure 10 a) Figure 10 b) and Figure 10 c) These correspond to the data changes of the drain current change rate di / dt (i.e., the "average change rate of drain current i") and the oscillation voltage V during multiple consecutive turn-on processes. osc initial peak value Vp Data changes and the output voltage V of the detection circuit o Data changes Figure 10 a) Figure 10 b) and Figure 10 c) The horizontal axis represents the number of times the tested SiC MOSFET was turned on (i.e., the "number of measurements" marked in the figure);

[0099] The experimental results above show that the initial peak value V p and the output voltage V of the detection circuit o The current decreases as the rate of increase of the drain current i during the turn-on process of the tested SiCMOSFET slows down, and experimental results show that the antenna sensor provided in this embodiment is repeatable.

[0100] To facilitate the adjustment of different gate resistors R g By comparing the experimental results, this application is also based on Figure 10 a) Figure 10 b) and Figure 10 The results shown in c) use different gate resistances as the abscissa and the drain current change rate di / dt (that is, the "average change rate of drain current i") and the initial peak value V as the ordinates. p and the output voltage V of the detection circuit o The average values ​​of the data are used as the ordinate; please refer to [link / reference]. Figure 10 As shown in d).

[0101] The average value of multiple measurements shows the average rate of change of the drain current i of the tested SiC MOSFET during the turn-on process (i.e., the average change of the drain current i). Figure 10 a) and Figure 10 d) The marked average rate of change of current ΔI / Δt) decreased by approximately 11.8%, with the initial peak V p (that is) Figure 10 b) and Figure 10 d) The initial peak value of the marked oscillation voltage V p and output voltage V o (that is) Figure 10 c) and Figure 10 d) The output voltage V of the marked peak sustaining circuit unit o The average change rates of the three decreased by 11.3% and 11.0% respectively, showing a continuous and consistent trend. This verifies the effectiveness of the antenna sensor provided in this embodiment in measuring the drain current change rate di / dt and its feasibility in the field of power electronic switching device condition monitoring.

[0102] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0103] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A non-contact antenna sensor for monitoring power electronic switching devices, characterized in that, The system includes a loop antenna located near the power electronic switching device under test, an oscillation circuit connected to both ends of the loop antenna, and a detection circuit connected to the output of the oscillation circuit. During the switching transient process of the power electronic switching device under test, the change in current *i* causes a change in the surrounding magnetic field *B*, which in turn causes a change in the planar magnetic flux *Φ* of the loop antenna, resulting in an induced electromotive force *e* at both ends of the loop antenna. Under the influence of this induced electromotive force *e*, the oscillation circuit outputs an oscillation voltage *V*. osc Its initial peak value V p The current change rate di / dt of the tested power electronic switching device during the switching transient process is directly proportional to the current change rate di / dt; the detection circuit extracts the oscillation voltage V. osc initial peak value V p and its output voltage V o Maintain at the initial peak V p Status until preset time.

2. The non-contact antenna sensor for monitoring power electronic switching devices according to claim 1, characterized in that, The proportional relationship between the induced electromotive force e and the rate of change of current di / dt is as follows: ； ； Where L is the coupling coefficient of the loop antenna; N is the number of turns of the loop antenna; λ m denoted as ρ, where ρ is the permeability of the loop antenna; A is the effective area of ​​the loop antenna; l is the distance from the loop antenna to the power electronic switching device under test; and μ0 is the permeability of free space.

3. The non-contact antenna sensor for monitoring power electronic switching devices according to claim 1, characterized in that, The oscillation circuit is an RLC oscillation circuit, including resistor R. p Inductor L p Capacitor C p Composition; wherein, the inductor L p Connected to one end of the loop antenna and resistor R p Between them, the other end of the loop antenna is grounded; the resistor R p The output terminal and capacitor C p One of the electrical terminals is connected, capacitor C p The other electrode of the capacitor is grounded; the capacitor C p The two terminals of the electrode are respectively connected to the detection circuit to input the oscillation voltage V into the detection circuit. osc .

4. The non-contact antenna sensor for monitoring power electronic switching devices according to claim 3, characterized in that, The oscillation period T of the oscillation circuit is not greater than twice the switching time t. sw Under the condition that the oscillation voltage V osc initial peak value V p It appears at time T / 2 and is directly proportional to the rate of change of current di / dt of the tested power electronic switching device during the switching transient process; wherein, the switching time t sw This refers to the power electronic switching device under test where the current rises from 0 to the load current i. L The turn-on time or from the load current i L The shutdown time drops to 0.

5. The non-contact antenna sensor for monitoring power electronic switching devices according to claim 4, characterized in that, The oscillation voltage V osc initial peak value V p The direct proportional relationship with the rate of change of current di / dt is as follows: ； Where δ is the attenuation coefficient of the oscillating circuit, and ω is the oscillation frequency of the oscillating circuit; This represents the direct proportion The prerequisite for the correspondence is that the oscillation period T of the oscillation circuit is not greater than twice the switching time t. sw .

6. The non-contact antenna sensor for monitoring power electronic switching devices according to claim 1, characterized in that, The formula for calculating the attenuation coefficient δ of the oscillation circuit is as follows: ； The formula for calculating the oscillation frequency ω of the oscillation circuit is as follows: ； The formula for calculating the oscillation period T of the oscillation circuit is as follows: 。 7. The non-contact antenna sensor for monitoring power electronic switching devices according to claim 1, characterized in that, The detection circuit includes an envelope detection circuit unit, a comparison circuit unit, a discharge circuit unit, and a peak maintenance circuit unit; wherein... Oscillation voltage V osc After being amplified by the amplifier, the signals are input to the envelope detection circuit unit and the peak sustaining circuit unit, respectively. The peak sustaining circuit unit captures the oscillation voltage V. osc initial peak value V p And the output voltage V of the detection circuit o Maintain at the initial peak V p state; The oscillation voltage V is transmitted through the envelope detection circuit unit. osc Converted to envelope voltage V env This is input to the comparator circuit unit; The envelope voltage V is measured by the comparison circuit unit. env With threshold voltage V TH When comparing, when the envelope voltage V env Greater than the threshold voltage V TH At that time, the comparator circuit unit output voltage V com A high level indicates a high voltage level; conversely, a low level indicates a low voltage level. The comparator circuit unit outputs a voltage V. com This is a low level; The output voltage V of the comparator circuit unit com The input is given to the discharge circuit unit, which outputs the voltage V based on the comparator circuit unit. com The high and low level states are used to determine its output voltage V. dis The high and low level states of the signal; The output voltage V of the discharge circuit unit dis A signal is input to the peak sustain circuit unit, selectively turning on the peak sustain electronic switch Q of the peak sustain circuit unit. k This allows the peak value to be maintained by the electronic switch Q. k Before the power electronic switching device under test undergoes its next switching transient, the holding capacitor C is adjusted. k The discharge of the capacitor C sets its voltage to zero to prevent the capacitor from being held in place. k The residual voltage can affect the next measurement.

8. The non-contact antenna sensor for monitoring power electronic switching devices according to claim 7, characterized in that, The discharge circuit unit includes an external capacitor C connected to it. x and resistance R x A steady-state trigger; the peak sustaining circuit unit includes a rectifier diode and a sustaining capacitor C. k and peak sustaining electronic switch Q k ;in, The comparator circuit unit outputs a voltage V. com After the input is given to the steady-state trigger, when the comparator circuit unit outputs voltage V com When the voltage is low, the steady-state trigger sets its output voltage V. dis The signal is set to high level, turning on the peak sustaining electronic switch Q. k Connect the external capacitor C between the current input pin (VCC) of the steady-state trigger and the external capacitor pin (1RC). x The external capacitor C x The other branch is connected to resistor R x The resistor pin (1C) is then connected; the output voltage V of the discharge circuit unit. dis High-level duration t of the signal d Due to external capacitor C x and resistance R x Decide; The peak sustaining electronic switch Q k The output voltage V of the drive electrode connected to the discharge circuit unit dis The signal is connected to the other two terminals of the sustaining capacitor C. k Between the positive and negative terminals, the holding capacitor C k The negative terminal is grounded, and a first rectifier diode and a second rectifier diode are connected between it and the positive terminal respectively to achieve voltage regulation. The oscillation voltage V after amplification by the amplifier osc Connect the connection point between the first rectifier diode and the second rectifier diode; The sustaining capacitor C k The positive and negative voltages are used as the output voltage V of the peak sustaining circuit unit. o ; Among them, the initial peak value V p The capture process is as follows: Peak sustaining electronic switch Q k The oscillation voltage V remains in the off state during this process. osc During the rise from 0, the amplifier output and the holding capacitor C k The second rectifier diode between the positive and negative terminals is at the oscillation voltage V. osc Under the action of , it conducts and maintains the capacitor C. k Charging; when the oscillation voltage V osc Rise to the initial peak V p At that time, maintain capacitor C k The voltage across the terminals reaches the initial peak value V p ; at the oscillation voltage V osc After the voltage drops, the second rectifier diode is reverse-biased and cuts off, maintaining capacitor C. k The voltage across the terminals remains at the initial peak value V. p level.

9. The non-contact antenna sensor for monitoring power electronic switching devices according to claim 7 or 8, characterized in that, The envelope detection circuit unit includes a rectifier diode and a resistor R. env and capacitor C env The filter circuit consists of a voltage comparator; the comparison circuit unit includes a voltage comparator; wherein, The resistor R env The two ends of the capacitor C env The positive and negative terminals are connected, and the capacitor C env The negative terminal is grounded, and a third rectifier diode and a fourth rectifier diode are connected between it and the positive terminal respectively; The oscillation voltage V after amplification by the amplifier osc Connect the connection point between the third rectifier diode and the fourth rectifier diode; The resistor R env The positive output terminal is connected to the positive input terminal of the voltage comparator, and the threshold voltage V TH As the negative input signal of the voltage comparator; The output of the voltage comparator is connected to the discharge circuit unit to convert the output voltage V of the comparator unit into voltage V. com Input to the discharge circuit unit.

10. The non-contact antenna sensor for monitoring power electronic switching devices according to claim 7 or 8, characterized in that, The peak sustain circuit unit's output voltage V is captured using an MCU. o The preset time is not less than 10 ns.

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