Coil turn-to-turn short circuit detection device, detection method and train

Abstract

The application provides a coil turn-to-turn short circuit detection device, a detection method and a train, and can be applied to the technical field of electrical testing and measurement. The device comprises: a power amplifier configured to output an excitation voltage with adjustable frequency to a measured coil; a fixed capacitor module configured to form a series resonance circuit together with the measured coil; a high-voltage voltage divider connected in parallel to both ends of the measured coil and configured to output an attenuation voltage proportional to the voltage across the measured coil; a current measurement unit configured to detect the loop current of the series resonance circuit; a voltage measurement unit connected to the output end of the power amplifier and the output end of the high-voltage voltage divider respectively and configured to detect the excitation voltage and the attenuation voltage respectively; and a control unit connected to the power amplifier, the current measurement unit and the voltage measurement unit respectively and configured to control the power amplifier to output the excitation voltage with adjustable frequency to the series resonance circuit and detect the turn-to-turn short circuit state of the measured coil based on the loop current, the excitation voltage and the attenuation voltage.

Description

Technical Field

[0001] This application relates to the field of electrical testing and measurement technology, and more specifically to a coil turn-to-turn short circuit detection device, detection method, and train. Background Technology

[0002] Inter-turn short circuits in coils are a common fault mode. Inter-turn short circuit detection techniques in related technologies typically employ either the pulse comparison method or the impedance measurement method. The former qualitatively determines the presence of an inter-turn short circuit by applying a high-voltage pulse and comparing the damped oscillation waveforms across the coil terminals, while the latter assesses the coil's condition by measuring the impedance change at a specific frequency.

[0003] While these methods can detect serious inter-turn short circuit faults to some extent, they often lack sufficient detection sensitivity when faced with minor inter-turn short circuits or early insulation degradation due to significant differences between the test signals and actual operating conditions or a lack of effective quantitative criteria. Summary of the Invention

[0004] In view of the above problems, this application provides a coil turn-to-turn short circuit detection device, detection method and train.

[0005] According to a first aspect of this application, a coil inter-turn short-circuit detection device is provided, comprising: a power amplifier for outputting a frequency-adjustable excitation voltage to the coil under test; a fixed capacitor module connected in series between the power amplifier and the coil under test, forming a series resonant circuit together with the coil under test; a high-voltage divider connected in parallel across the two ends of the coil under test for outputting an attenuated voltage proportional to the voltage across the two ends of the coil under test; a current measuring unit connected in series in the series resonant circuit for detecting the loop current of the series resonant circuit; a voltage measuring unit connected to the output terminals of the power amplifier and the high-voltage divider respectively for detecting the excitation voltage and the attenuated voltage respectively; and a control unit connected to the power amplifier, the current measuring unit, and the voltage measuring unit respectively for controlling the power amplifier to output a frequency-adjustable excitation voltage to the series resonant circuit, and detecting the inter-turn short-circuit state of the coil under test based on the loop current, the excitation voltage, and the attenuated voltage.

[0006] According to an embodiment of this application, the fixed capacitor module includes a plurality of fixed capacitors and at least one switch; the plurality of fixed capacitors are connected to a series resonant circuit through at least one switch to match the coils under test with different inductance values.

[0007] According to an embodiment of this application, the current measuring unit includes a current clamp or a current transformer; the current clamp or current transformer is connected in series in a series resonant circuit for detecting the loop current of the series resonant circuit in a non-contact or contact manner.

[0008] According to an embodiment of this application, the voltage measurement unit includes an oscilloscope having a first channel, a second channel, and a third channel; the first channel is connected to a current measurement unit for detecting a first waveform signal of the loop current; the second channel is connected to the output terminal of a power amplifier for detecting a second waveform signal of the excitation voltage; and the third channel is connected to the output terminal of a high-voltage divider for detecting a third waveform signal of the attenuated voltage.

[0009] The second aspect of this application provides a method for detecting inter-turn short circuits in a coil, applicable to any of the aforementioned inter-turn short circuit detection devices, comprising: controlling a power amplifier to output a frequency-adjustable excitation voltage to a series resonant circuit composed of a fixed capacitor module and the coil under test; detecting the loop current of the series resonant circuit through a current measurement unit, and detecting the excitation voltage and the attenuated voltage output by a high-voltage divider connected in parallel across the coil under test through a voltage measurement unit; adjusting the output frequency of the power amplifier to minimize the phase difference between the loop current and the excitation voltage, and recording the output frequency of the power amplifier at which the phase difference is minimized as the series resonant frequency of the coil under test; controlling the power amplifier to increase the excitation voltage at the series resonant frequency, thereby increasing the actual voltage across the coil under test; determining the actual voltage across the coil under test in real time based on the attenuated voltage until the actual voltage reaches the target test voltage; and detecting the inter-turn short circuit state of the coil under test based on the excitation voltage, the actual voltage, and the series resonant frequency.

[0010] According to an embodiment of this application, by adjusting the output frequency of the power amplifier to minimize the phase difference between the loop current and the excitation voltage, the output frequency of the power amplifier at which the phase difference is minimized is recorded as the series resonant frequency of the coil under test. This includes: setting an initial output frequency of the power amplifier; gradually adjusting the output frequency according to a preset frequency step size, and at each output frequency, detecting the loop current through a current measurement unit and detecting the excitation voltage through a voltage measurement unit; determining the phase difference between the loop current and the excitation voltage, and recording the output frequency of the power amplifier at which the phase difference is minimized as the series resonant frequency of the coil under test.

[0011] According to an embodiment of this application, determining the actual voltage across the coil under test in real time based on the attenuation voltage includes: proportionally converting the attenuation voltage according to the voltage division ratio of the high voltage divider to determine the actual voltage across the coil under test, wherein the voltage division ratio is the ratio of the voltage across the coil under test to the attenuation voltage.

[0012] According to an embodiment of this application, detecting the inter-turn short circuit state of a coil under test based on the excitation voltage, actual voltage, and series resonant frequency includes: obtaining the reference resonant frequency and reference quality factor of the coil under test; determining the measured quality factor of the coil under test based on the ratio of the actual voltage across the coil under test to the excitation voltage; comparing the series resonant frequency and the measured quality factor with the reference resonant frequency and the reference quality factor, respectively; and determining that an inter-turn short circuit exists in the coil under test when the difference between the series resonant frequency and the reference resonant frequency is positive and exceeds a first deviation threshold, and the difference between the measured quality factor and the reference quality factor is negative and exceeds a second deviation threshold.

[0013] According to an embodiment of this application, after comparing the series resonant frequency and the measured quality factor with the reference resonant frequency and the reference quality factor respectively, the method further includes: determining that the coil under test does not have an inter-turn short circuit if the difference between the series resonant frequency and the reference resonant frequency is not positive or does not exceed a first deviation threshold, or if the difference between the measured quality factor and the reference quality factor is not negative or does not exceed a second deviation threshold.

[0014] According to an embodiment of this application, obtaining the reference resonant frequency and reference quality factor of the coil under test includes: testing a reference coil of the same model as the coil under test to obtain the resonant frequency and quality factor of the reference coil; and using the resonant frequency and quality factor of the reference coil as the reference resonant frequency and reference quality factor of the coil under test, respectively.

[0015] According to an embodiment of this application, after the power amplifier increases the excitation voltage at the series resonant frequency, the method further includes: if, after a preset boosting time, the actual voltage across the coil under test still fails to reach the preset target test voltage, determining that the coil under test has resonant point drift or damage.

[0016] According to an embodiment of this application, after adjusting the output frequency of the power amplifier to minimize the phase difference between the loop current and the excitation voltage, the method further includes: determining that the coil under test has not entered a resonant state when the phase difference between the loop current and the excitation voltage is greater than a preset phase threshold and the actual voltage across the coil under test is lower than a preset target test voltage.

[0017] According to an embodiment of this application, the current measuring unit is a current clamp; after detecting the loop current of the series resonant circuit through the current measuring unit, the method further includes: determining that the loop current exceeds the measurement range of the current clamp in the case of waveform distortion of the loop current.

[0018] A third aspect of this application provides a train including any of the aforementioned coil turn-to-turn short-circuit detection devices.

[0019] Through the embodiments of this application, the power amplifier outputs an adjustable excitation voltage, which can adapt to the detection requirements of coils with different inductances and be used to find the resonant frequency. A fixed capacitor module is connected in series with the coil under test to form a series resonant circuit. It utilizes the characteristic that the electrical parameters change significantly during resonance to sensitively reflect small changes in the coil inductance. At the same time, the use of a fixed capacitor simplifies circuit adjustment. A high-voltage divider is connected in parallel across the coil under test to output a proportionally decaying voltage, which solves the problem that the voltage across the coil is too high to be directly measured during resonance, thus ensuring measurement safety. A current measurement unit is connected in series in the loop to detect the loop current, providing a direct current basis for judging the resonance state and impedance changes caused by short circuits. The voltage measurement unit detects the excitation voltage and decay voltage respectively, which facilitates the accurate acquisition of the actual values ​​of the input and coil terminal voltages to assist in the analysis of resonance characteristics. The control unit controls the output of the power amplifier and collects the loop current, excitation voltage, and decay voltage for comprehensive judgment, realizing the automation of the detection process. Furthermore, the accuracy of inter-turn short circuit state identification is improved through multi-parameter joint analysis. Attached Figure Description

[0020] The above-mentioned contents, other objects, features and advantages of this application will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:

[0021] Figure 1 A block diagram of a coil turn-to-turn short-circuit detection device according to an embodiment of this application is shown schematically.

[0022] Figure 2 A schematic diagram of the equivalent circuit of a series resonance according to an embodiment of this application is shown.

[0023] Figure 3 A block diagram of a coil turn-to-turn short-circuit detection device according to an embodiment of this application is shown schematically;

[0024] Figure 4 A flowchart illustrating a coil turn-to-turn short-circuit detection method according to an embodiment of this application is shown schematically.

[0025] Figure 5 A typical waveform diagram at resonance according to an embodiment of this application is schematically shown;

[0026] Figure 6 A test control flowchart according to an embodiment of this application is illustrated schematically;

[0027] Figure 7 A schematic diagram of a train according to an embodiment of this application is shown. Detailed Implementation

[0028] The embodiments of this application will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of this application. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of this application for ease of explanation. However, it will be apparent that one or more embodiments may be implemented without these specific details. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of this application.

[0029] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. The terms “comprising,” “including,” etc., as used herein indicate the presence of features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0030] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0031] In electrical equipment such as maglev trains, transformers, and motors, the quality of the inter-turn insulation of the coils directly determines the operational reliability and safety of the equipment. Inter-turn short circuits are a common and serious type of fault during the operation of such equipment, thus requiring effective detection during production and maintenance. Currently, the conventional testing methods used in the industry mainly include direct high-voltage testing, inductance measurement, and pulse surge testing. However, direct high-voltage testing requires large-volume, high-cost high-voltage transformers, posing a risk of irreversible damage to the coil insulation; inductance measurement can only obtain the overall inductance value of the coil, and since the change in inductance caused by inter-turn short circuits is extremely small, ordinary measuring instruments cannot accurately distinguish it, and this method cannot reflect the insulation withstand voltage performance of the coil; although pulse surge testing can compare the coil condition to some extent, its equipment structure is complex and the operation threshold is high, which is not conducive to rapid on-site deployment.

[0032] The relevant technologies still face limitations in practical applications, especially for large coils with high inductance and high operating voltage, such as magnetic levitation electromagnets. Conventional testing methods struggle to balance test voltage, detection sensitivity, and equipment cost, failing to ensure both the safety and effectiveness of the testing process. Furthermore, the related testing systems generally lack convenient daily self-calibration mechanisms, preventing testers from quickly verifying the test bench's operational status before testing. This further limits the practicality and reliability of the technologies in routine industrial testing.

[0033] This application provides a coil inter-turn short circuit detection device, detection method, and train. The device includes an adjustable frequency power amplifier, a fixed capacitor module, a high voltage divider, a current measurement unit, and a voltage measurement unit. During testing, the output frequency of the power amplifier is adjusted to create a series resonance between the inductance of the coil under test and the fixed capacitor. Utilizing the voltage rise characteristic at resonance, a higher test voltage is generated across the coil under test using a lower power supply voltage. By measuring the resonant frequency, power supply voltage / current, coil voltage / current, and phase relationship, and comparing these measurements with a pre-established reference coil profile, it can be determined whether the coil has an inter-turn short circuit or other insulation defects.

[0034] Figure 1 A schematic block diagram of a coil turn-to-turn short-circuit detection device according to an embodiment of this application is shown. It includes a power amplifier 110, a fixed capacitor module 120, a high-voltage divider 130, a current measurement unit 140, and a voltage measurement unit 150.

[0035] A power amplifier is used to output a frequency-adjustable excitation voltage to the coil under test.

[0036] A fixed capacitor module is connected in series between the power amplifier and the coil under test, and together with the coil under test, they form a series resonant circuit.

[0037] A high-voltage divider, connected in parallel across the two ends of the coil being tested, is used to output a voltage attenuated in proportion to the voltage across the coil being tested.

[0038] The current measuring unit is connected in series in the series resonant circuit and is used to detect the loop current of the series resonant circuit.

[0039] The voltage measurement unit is connected to the output terminals of the power amplifier and the high voltage divider, respectively, to detect the excitation voltage and the attenuation voltage.

[0040] The control unit is connected to the power amplifier, current measurement unit and voltage measurement unit respectively. It is used to control the power amplifier to output a frequency-adjustable excitation voltage to the series resonant circuit, and to detect the inter-turn short circuit state of the coil under test based on the loop current, excitation voltage and decay voltage.

[0041] In this embodiment, the power amplifier is an adjustable frequency power amplifier capable of outputting a sinusoidal voltage. Its output frequency range is set from 100Hz to 5kHz, and the effective value of the output excitation voltage is up to 300V. The power amplifier is controlled by a control unit via internal power switching devices and drive circuitry.

[0042] A fixed capacitor module is connected in series between the power amplifier and the coil under test, forming a series resonant circuit together. For example, the fixed capacitor module uses a high-voltage non-inductive capacitor with a capacitance of 0.56μF. The inductance of the coil under test is matched with the capacitance of the fixed capacitor module. When the frequency of the excitation voltage output by the power amplifier is equal to or close to the natural frequency of this series resonant circuit, the circuit resonates in series, and a high voltage much higher than the excitation voltage is generated across the coil under test.

[0043] Figure 2 An equivalent circuit diagram of a series resonance according to an embodiment of this application is schematically shown.

[0044] like Figure 2 As shown, the series resonant equivalent circuit includes an excitation voltage source Us, an equivalent resistance Rs, an equivalent inductance L, and a capacitor C. The excitation voltage source Us, equivalent resistance Rs, equivalent inductance L, and capacitor C are connected in series to form a closed loop. The equivalent resistance Rs and equivalent inductance L are marked with positive and negative polarity symbols, respectively. The capacitor C is led out at both ends as the circuit output terminals, and is marked with the output voltage Uout and its positive and negative polarities. A loop current I flows through the closed loop from the excitation voltage source Us to the capacitor C.

[0045] In the embodiments of this application, the equivalent inductance L corresponds to the inductance parameter of the coil under test, the equivalent resistance Rs corresponds to the equivalent series resistance of the coil under test, the capacitor C corresponds to the fixed capacitor module, the excitation voltage source Us corresponds to the excitation voltage output by the power amplifier, and the output voltage Uout corresponds to the attenuation voltage detected by the high voltage divider.

[0046] A high-voltage divider is connected in parallel across the coil under test to output a voltage attenuated proportionally to the voltage across the coil. For example, a resistor-capacitor divider with a division ratio of 1000:1 can be used. Its high-voltage input is connected to the coil under test, and its low-voltage output is the attenuated voltage. Because the voltage across the coil under test is high at resonance, the high-voltage divider proportionally attenuates the high voltage to a low-voltage signal, facilitating safe acquisition by low-voltage measuring equipment and achieving electrical isolation between the high-voltage side and the measuring side.

[0047] A current measuring unit is connected in series in a series resonant circuit to detect the loop current of the series resonant circuit. For example, the current measuring unit can be a current clamp or a current transformer. Since the current is the same everywhere in a series circuit, the current measuring unit can be connected in series between the output of the power amplifier and the fixed capacitor module, or in series between the fixed capacitor module and the coil under test. The current it detects is the loop current flowing through the coil under test.

[0048] The voltage measurement unit is connected to the outputs of both the power amplifier and the high-voltage divider. For example, the voltage measurement unit includes at least two independent voltage detection channels. The input of the first channel is directly connected to the output of the power amplifier for real-time detection and acquisition of the excitation voltage signal. The input of the second channel is connected to the output of the high-voltage divider for detecting the attenuated voltage output after proportional attenuation. Each detection channel contains a voltage sensor and signal conditioning circuitry, capable of isolating, filtering, and amplitude adjusting the input analog voltage signal, subsequently converting it into a digital signal and transmitting it to the control unit.

[0049] Since the voltage division ratio of the high-voltage divider is a fixed value, the control unit can accurately calculate the actual voltage across the coil under test based on the value of the attenuated voltage and the voltage division ratio.

[0050] Through the above connection method, the voltage measurement unit realizes independent and synchronous detection of excitation voltage and decay voltage, providing accurate voltage data for subsequent comprehensive determination of inter-turn short circuit status based on loop current, excitation voltage and decay voltage.

[0051] The control unit is connected to the power amplifier, current measurement unit, and voltage measurement unit, respectively. In a specific implementation, the control unit consists of an industrial computer or programmable logic controller (PLC), a touch screen, and a data acquisition card.

[0052] In terms of hardware connectivity, the control unit connects to the power amplifier via a communication bus to send frequency and voltage amplitude commands to the power amplifier, thereby controlling the power amplifier to output a frequency-adjustable excitation voltage to the series resonant circuit. The control unit also establishes signal connections with the current measurement unit and the voltage measurement unit via a data acquisition card, enabling real-time acquisition of the loop current signal detected by the current measurement unit and the excitation and attenuation voltage signals detected by the voltage measurement unit.

[0053] Internally, the control unit includes a storage module and a processing module. The storage module pre-stores reference data for different types of qualified coils, including parameters such as resonant frequency, quality factor, voltage ratio, and phase relationship. The processing module is configured to determine the inter-turn short-circuit state of the coil under test based on the loop current, excitation voltage, and decay voltage.

[0054] For example, the processing module evaluates the current state parameters of the series resonant circuit based on the attenuation voltage and the characteristics of the resonant circuit formed by the fixed capacitor module and the coil under test, combined with the excitation voltage and loop current. The processing module compares and analyzes the real-time acquired parameters with reference data in the storage module. When a significant increase in resonant frequency and a decrease in quality factor are detected, it determines that there is an inter-turn short circuit in the coil under test; when the parameter deviation is within the allowable range, the coil is deemed qualified. A touchscreen connected to the processing module provides a human-machine interface, displaying detection data, status prompts, and alarm information.

[0055] Through the embodiments of this application, the power amplifier outputs an adjustable excitation voltage, which can adapt to the detection requirements of coils with different inductances and be used to find the resonant frequency. A fixed capacitor module is connected in series with the coil under test to form a series resonant circuit. It utilizes the characteristic that the electrical parameters change significantly during resonance to sensitively reflect small changes in the coil inductance. At the same time, the use of a fixed capacitor simplifies circuit adjustment. A high-voltage divider is connected in parallel across the coil under test to output a proportionally decaying voltage, which solves the problem that the voltage across the coil is too high to be directly measured during resonance, thus ensuring measurement safety. A current measurement unit is connected in series in the loop to detect the loop current, providing a direct current basis for judging the resonance state and impedance changes caused by short circuits. The voltage measurement unit detects the excitation voltage and decay voltage respectively, which facilitates the accurate acquisition of the actual values ​​of the input and coil terminal voltages to assist in the analysis of resonance characteristics. The control unit controls the output of the power amplifier and collects the loop current, excitation voltage, and decay voltage for comprehensive judgment, realizing the automation of the detection process. Furthermore, the accuracy of inter-turn short circuit state identification is improved through multi-parameter joint analysis.

[0056] In some embodiments, the fixed capacitor module includes a plurality of fixed capacitors and at least one switch; the plurality of fixed capacitors are connected to a series resonant circuit through at least one switch to match the coils under test with different inductance values.

[0057] In this embodiment, multiple fixed capacitors are connected to a series resonant circuit via at least one switch. For example, multiple fixed capacitors are connected in parallel, with each fixed capacitor connected in series with a switch, or multiple fixed capacitors are combined through a switch matrix and finally connected in series in the loop between the power amplifier and the coil under test, forming a series resonant circuit together with the coil under test.

[0058] At least one switch's control terminal can be connected to the control unit. The control unit drives the corresponding switch to perform the action based on the input model of the coil under test or the estimated parameters, thereby completing the automatic matching and switching of the capacitor.

[0059] Since the resonant frequency of a series resonant circuit is determined by both the total inductance and total capacitance of the circuit, and the inductance values ​​of different models or specifications of the coil under test vary, a matching capacitance value needs to be selected based on the inductance value of the coil under test in order for the series resonant circuit to resonate within the adjustable frequency range of the power amplifier.

[0060] Through the embodiments of this application, controlling the on / off state of at least one switch allows selection of one or more fixed capacitors to be connected to the circuit, thereby changing the total capacitance value connected to the series resonant circuit. This structure enables the fixed capacitor module to adapt to and match the tested coils with different inductance values, ensuring that it can be adjusted to a resonant state for different tested coils, thus expanding the applicability of the detection device.

[0061] In some embodiments, the current measuring unit includes a current clamp or a current transformer; the current clamp or current transformer is connected in series in a series resonant circuit for detecting the loop current of the series resonant circuit in a non-contact or contact manner.

[0062] In this embodiment, when the current measuring unit uses a current clamp, the current clamp is a clamp-on current transformer. Its jaws are directly closed to the outside of the conductor of the series resonant circuit, and current detection can be achieved without disconnecting the circuit.

[0063] The current clamp is based on the principle of electromagnetic induction, non-contactly coupling changes in the magnetic field around a conductor to obtain the loop current signal of a series resonant circuit. Since the series resonant circuit is a series structure, the current magnitude is equal at all points in the circuit. Therefore, the current clamp can be clamped onto any wire connected to a power amplifier, a fixed capacitor module, or the coil under test.

[0064] When a current measuring unit uses a current transformer, the current transformer includes a primary winding and a secondary winding.

[0065] In contact-type detection, the primary winding of the current transformer is directly connected in series in a series resonant circuit, for example, between the output of a power amplifier and a fixed capacitor module. In this case, the loop current flows directly through the primary winding of the current transformer, and through electromagnetic coupling, the secondary winding outputs a detection signal proportional to the loop current, thus achieving contact-type detection.

[0066] Through the embodiments of this application, the current clamp or current transformer converts the detected loop current into a measurable electrical signal and transmits it to the control unit for subsequent resonance state analysis and inter-turn short circuit determination.

[0067] In some embodiments, the voltage measurement unit includes an oscilloscope having a first channel, a second channel, and a third channel; the first channel is connected to the current measurement unit for detecting a first waveform signal of the loop current; the second channel is connected to the output of the power amplifier for detecting a second waveform signal of the excitation voltage; and the third channel is connected to the output of the high-voltage divider for detecting a third waveform signal of the attenuated voltage.

[0068] In this embodiment of the application, an oscilloscope is an electronic measuring instrument used to acquire and display the waveform of an electrical signal changing over time. Its multiple input channels can independently receive external signals and convert them into digital waveform data.

[0069] In terms of hardware connection, the first channel is connected to the current measurement unit. The current measurement unit converts the detected loop current of the series resonant circuit into a voltage signal proportional to it. The first channel acquires this voltage signal to detect the first waveform signal of the loop current, thereby obtaining the amplitude, frequency, and phase characteristics of the loop current.

[0070] The second channel is connected to the output of the power amplifier. This second channel directly acquires the excitation voltage signal output by the power amplifier and is used to detect the second waveform signal of the excitation voltage.

[0071] The third channel is connected to the output of the high-voltage divider. Since the high-voltage divider is connected in parallel across the coil under test, its output terminal outputs an attenuated voltage that is proportional to the actual voltage across the coil under test. The third channel acquires this attenuated voltage signal and uses it to detect the third waveform signal of the attenuated voltage. This signal reflects the actual waveform and amplitude information of the voltage across the coil under test.

[0072] Figure 3 A block diagram of a coil turn-to-turn short-circuit detection device according to an embodiment of this application is schematically shown. It includes a four-quadrant power amplifier (labeled 0-300V), a function control module, an oscilloscope, an industrial computer, a digital test meter, and the unit under test.

[0073] The four-quadrant power amplifier has signal communication terminals, voltage monitoring terminals, and current monitoring terminals, and its output terminals are connected to the function control module. The function control module integrates a voltage switching module, current measurement, compensation capacitors, voltage measurement, and a measurement transmitter. The output terminals of the function control module are connected to two units under test. The oscilloscope has a first channel CH1, a second channel CH2, and a third channel CH3. An industrial computer and digital test meters establish control and data connections with the four-quadrant power amplifier, the function control module, and the oscilloscope, respectively.

[0074] In this embodiment, the oscilloscope's three channels simultaneously acquire the loop current waveform, the power supply excitation voltage waveform, and the coil attenuation voltage waveform. These waveform signals are transmitted to the control unit, enabling the control unit to directly observe the phase relationship between the signals. For example, it can determine whether the excitation voltage and the loop current are in phase to determine the series resonance state, or compare the phase difference between the coil voltage and current, thereby providing waveform basis for determining the inter-turn short-circuit state of the coil under test.

[0075] Figure 4 A flowchart illustrating a coil turn-to-turn short-circuit detection method according to an embodiment of this application is shown schematically.

[0076] Step S410: Control the power amplifier to output a frequency-adjustable excitation voltage to the series resonant circuit composed of the fixed capacitor module and the coil under test.

[0077] In this embodiment, the control unit is connected to the power amplifier via a communication bus and sends frequency and voltage amplitude commands to it.

[0078] The output of the power amplifier is connected to one end of a fixed capacitor module via a wire, and the other end of the fixed capacitor module is connected to the coil under test. The three are connected in series to form a series resonant circuit.

[0079] The power amplifier responds to the command and outputs a sinusoidal excitation voltage. The frequency of this excitation voltage can be adjusted from 100Hz to 5kHz, and the amplitude can reach up to 300V. At this time, the excitation voltage is applied across the series resonant circuit to provide signal excitation for subsequent parameter detection.

[0080] In step S420, the loop current of the series resonant circuit is detected by the current measurement unit, and the excitation voltage and the attenuated voltage output by the high voltage divider connected in parallel across the coil under test are detected by the voltage measurement unit.

[0081] In this embodiment, the current measuring unit is connected in series in the loop wire of the series resonant circuit, for example, in series between the power amplifier and the fixed capacitor module, for detecting the loop current.

[0082] Since the current is equal at all points in a series circuit, the detected current is the loop current of the entire series resonant circuit.

[0083] The voltage measurement unit includes at least two detection channels. The first channel is directly connected to the output of the power amplifier for detecting the excitation voltage. The second channel is connected to the output of the high-voltage divider. The high-voltage divider is connected in parallel across the coil under test and contains an internal voltage-dividing resistor network to proportionally attenuate the actual high voltage across the coil under test into a low-voltage signal, i.e., attenuated voltage.

[0084] Step S430: By adjusting the output frequency of the power amplifier, the phase difference between the loop current and the excitation voltage is minimized. The output frequency of the power amplifier when the phase difference is minimized is recorded as the series resonant frequency of the coil under test.

[0085] The control unit sets the initial output frequency of the power amplifier, for example, by estimating the inductance value of the coil under test and the capacitance value of the fixed capacitor module. The control unit gradually adjusts the output frequency in preset frequency steps, for example, by increasing or decreasing it by 1Hz each time.

[0086] At each output frequency, the control unit detects the loop current through the current measurement unit and the excitation voltage through the voltage measurement unit, and then calculates the phase difference between the two.

[0087] When the phase difference between the loop current and the excitation voltage is detected to be close to zero or reach its minimum value, it indicates that the circuit has achieved series resonance. The control unit records this output frequency as the series resonant frequency of the coil under test. After adjustment, if the phase difference between the loop current and the excitation voltage is still greater than the preset phase threshold, and the actual voltage across the coil under test, calculated by attenuating the voltage, is lower than the preset target test voltage, it is determined that the coil under test has not entered the resonance state, and a prompt is made to check the connection or frequency setting.

[0088] Step S440: Control the power amplifier to increase the excitation voltage at the series resonant frequency, so that the actual voltage across the coil under test increases; determine the actual voltage across the coil under test in real time based on the attenuation voltage, until the actual voltage reaches the target test voltage.

[0089] The control unit maintains the power amplifier at its series resonant frequency output and gradually increases the output amplitude of the excitation voltage. In the resonant state, the voltage across the tested coil will be significantly higher than the excitation voltage. The high-voltage divider outputs a decaying voltage in real time that is proportional to the actual voltage across the tested coil.

[0090] The control unit determines the actual voltage across the coil under test in real time based on the attenuation voltage. Specifically, the attenuation voltage is proportionally converted according to the voltage division ratio of the high voltage divider to determine the actual voltage. The voltage division ratio is the ratio of the voltage across the coil under test to the attenuation voltage.

[0091] For example, when the voltage division ratio is 1000:1, if the attenuation voltage is 2.5V, the actual voltage is 2500V. The control unit continuously monitors this actual voltage, and stops boosting when the actual voltage reaches the preset target test voltage. If, after a preset boosting time, the actual voltage across the coil under test still fails to reach the preset target test voltage, it is determined that the coil under test has resonant point drift or is damaged.

[0092] Step S450: Based on the excitation voltage, actual voltage and series resonant frequency, detect the inter-turn short circuit state of the coil under test.

[0093] The control unit acquires the reference resonant frequency and reference quality factor of the coil under test. Based on the ratio of the actual voltage across the coil under test to the excitation voltage, the control unit determines the measured quality factor Q of the coil under test (i.e., Q = actual voltage / excitation voltage).

[0094] The control unit compares the series resonant frequency and the measured quality factor with the reference resonant frequency and the reference quality factor, respectively.

[0095] If the difference between the series resonant frequency and the reference resonant frequency is positive and exceeds the first deviation threshold, and the difference between the measured quality factor and the reference quality factor is negative and exceeds the second deviation threshold, it is determined that there is an inter-turn short circuit in the coil under test.

[0096] If the difference between the series resonant frequency and the reference resonant frequency is not positive or does not exceed the first deviation threshold, or the difference between the measured quality factor and the reference quality factor is not negative or does not exceed the second deviation threshold, then it is determined that there is no inter-turn short circuit in the coil under test.

[0097] In this embodiment, by adjusting the output frequency of the power amplifier to minimize the phase difference between the loop current and the excitation voltage, the output frequency at this point is recorded as the series resonant frequency, thereby accurately obtaining the characteristic frequency corresponding to the inductance of the coil under test. The power amplifier is controlled to increase the excitation voltage at this series resonant frequency, and the actual voltage across the coil under test is determined in real time based on the attenuation voltage until the target test voltage is reached. The series resonance principle is used to achieve accurate application and monitoring of high voltage across the coil under test with a relatively low excitation voltage. The inter-turn short circuit state is determined based on the excitation voltage, the actual voltage, and the series resonant frequency. Since the inter-turn short circuit will cause changes in the coil inductance and equivalent resistance, it will cause the series resonant frequency and the correspondence between the excitation voltage and the actual voltage to shift. Therefore, by combining the above parameters, the inter-turn short circuit state of the coil under test can be reasonably inferred.

[0098] In some embodiments, by adjusting the output frequency of the power amplifier to minimize the phase difference between the loop current and the excitation voltage, the output frequency of the power amplifier at which the phase difference is minimized is recorded as the series resonant frequency of the coil under test. This includes: setting an initial output frequency of the power amplifier; gradually adjusting the output frequency according to a preset frequency step size, and at each output frequency, detecting the loop current through a current measurement unit and detecting the excitation voltage through a voltage measurement unit; determining the phase difference between the loop current and the excitation voltage, and recording the output frequency of the power amplifier at which the phase difference is minimized as the series resonant frequency of the coil under test.

[0099] In this embodiment, the initial output frequency of the power amplifier is set. For example, the control unit estimates an approximate frequency as the initial output frequency by using the series resonant frequency formula based on the model of the coil under test or the estimated inductance parameters, combined with the capacitance value of the fixed capacitor module; or, the control unit directly sets a default intermediate frequency value (e.g., 1kHz) as the initial output frequency. Simultaneously, the control unit controls the power amplifier to output a low voltage amplitude (e.g., 20V) to limit the loop current during the search process and ensure circuit safety.

[0100] The output frequency is gradually adjusted according to a preset frequency step size, and at each output frequency, the circuit current is detected by the current measurement unit and the excitation voltage is detected by the voltage measurement unit.

[0101] For example, the preset frequency step size is pre-configured by the control unit, such as set to 1Hz or 5Hz. The control unit controls the power amplifier to gradually increase or decrease the output frequency from the initial output frequency at preset frequency step intervals. Whenever the power amplifier stabilizes at an output frequency, the control unit acquires the loop current signal of the series resonant circuit through the current measurement unit and the excitation voltage signal output from the output terminal of the power amplifier through the voltage measurement unit.

[0102] Determine the phase difference between the loop current and the excitation voltage, and record the output frequency of the power amplifier when the phase difference is minimum as the series resonant frequency of the coil under test.

[0103] For example, the control unit performs phase analysis on the acquired loop current signal and excitation voltage signal. In a series circuit, when the phase difference between the loop current and the excitation voltage is close to zero, the circuit exhibits pure resistivity, and at this time, the circuit reaches a series resonance state. The control unit calculates and compares the phase difference values ​​of the loop current and the excitation voltage at different output frequencies. When the phase difference between the two is detected to reach its minimum value (i.e., closest to zero) at a certain output frequency, the control unit records this output frequency as the series resonant frequency of the coil under test. This frequency is the resonant point jointly determined by the inductance of the coil under test and the capacitance of the fixed capacitor module.

[0104] Through the embodiments of this application, by gradually adjusting the output frequency and detecting the phase difference between the loop current and the excitation voltage in real time, the series resonant frequency can be accurately locked, thereby improving the accuracy of detecting the inductance of the coil under test and the inter-turn short circuit status.

[0105] In some embodiments, determining the actual voltage across the coil under test in real time based on the attenuation voltage includes: proportionally converting the attenuation voltage according to the voltage division ratio of the high voltage divider to determine the actual voltage across the coil under test, wherein the voltage division ratio is the ratio of the voltage across the coil under test to the attenuation voltage.

[0106] In this embodiment, the high-voltage divider is internally composed of a series-connected resistor network or a resistor-capacitor network, which is connected in parallel across the two ends of the coil being tested. The voltage division ratio of the high-voltage divider is a known fixed constant, pre-calibrated by the parameters of its internal components.

[0107] For example, when the voltage division ratio of the high voltage divider is 1000:1, it indicates that the voltage across the measured coil is always 1000 times the attenuated voltage.

[0108] During testing, the voltage measurement unit detects the attenuated voltage output from the high-voltage divider and transmits this signal to the control unit. The control unit pre-stores the voltage division ratio parameters of the high-voltage divider used. When voltage determination is required, the control unit reads the real-time detected attenuated voltage value and performs a proportional conversion based on the voltage division ratio. That is, by multiplying the attenuated voltage by the voltage division ratio, the actual voltage across the coil under test is calculated.

[0109] Through the embodiments of this application, since the voltage measurement unit continuously collects and updates the attenuated voltage, the control unit can repeatedly execute the above proportional conversion steps, thereby determining the actual voltage across the coil under test in real time and accurately, while avoiding the safety risks caused by directly measuring high voltage.

[0110] In some embodiments, detecting the inter-turn short circuit state of the coil under test based on the excitation voltage, the actual voltage, and the series resonant frequency includes: acquiring the reference resonant frequency and the reference quality factor of the coil under test; determining the measured quality factor of the coil under test based on the ratio of the actual voltage across the coil under test to the excitation voltage; comparing the series resonant frequency and the measured quality factor with the reference resonant frequency and the reference quality factor, respectively; and determining that the coil under test has an inter-turn short circuit if the difference between the series resonant frequency and the reference resonant frequency is positive and exceeds a first deviation threshold, and the difference between the measured quality factor and the reference quality factor is negative and exceeds a second deviation threshold.

[0111] In this embodiment, the control unit's storage module pre-establishes reference profile data for different coil models. The reference resonant frequency and reference quality factor are obtained by pre-testing a qualified reference coil of the same model as the coil under test.

[0112] Once the test reaches a stable state, the control unit reads the excitation voltage detected by the voltage measurement unit, as well as the actual voltage across the tested coil calculated based on the attenuated voltage. The control unit calculates the ratio between the actual voltage and the excitation voltage, and determines this ratio as the measurement quality factor of the tested coil. This parameter reflects the resonant boost characteristics of the current series resonant circuit.

[0113] The control unit calculates the difference between the series resonant frequency and the reference resonant frequency. When this difference is positive, it indicates that the resonant frequency of the coil under test is higher than the acceptable reference value. Since the capacitance value of the fixed capacitor module is fixed, according to the series resonant frequency formula, an increase in the resonant frequency means a decrease in the inductance of the coil under test. This decrease in inductance is usually caused by a reduction in the effective number of turns due to an inter-turn short circuit in the coil.

[0114] Simultaneously, the control unit calculates the difference between the measured quality factor and the reference quality factor. A negative difference indicates that the quality factor of the current tested coil is lower than the acceptable reference value, suggesting increased circuit losses or weakened resonant energy concentration. This corresponds to increased resistance or changes in magnetic coupling caused by inter-turn short circuits. The first and second deviation thresholds are preset allowable error ranges for the system, for example, a frequency deviation of 0.5% and a quality factor deviation of 5%. When the difference in series resonant frequencies is positive and greater than the first deviation threshold, and the difference in measured quality factors is negative and its absolute value is greater than the second deviation threshold, the control unit determines that an inter-turn short circuit exists in the tested coil and outputs corresponding fault information.

[0115] Through the embodiments of this application, the series resonant frequency and the measured quality factor are compared with the reference value respectively, and when the frequency is positively biased and the quality factor is negatively biased, it is determined to be an inter-turn short circuit. This realizes dual verification of the inter-turn short circuit state of the coil, effectively avoids misjudgment of a single parameter, and improves the accuracy of detection.

[0116] In some embodiments, after comparing the series resonant frequency and the measured quality factor with the reference resonant frequency and the reference quality factor, the method further includes: determining that the coil under test does not have an inter-turn short circuit if the difference between the series resonant frequency and the reference resonant frequency is not positive or does not exceed a first deviation threshold, or if the difference between the measured quality factor and the reference quality factor is not negative or does not exceed a second deviation threshold.

[0117] In the embodiments of this application, the control unit calculates the difference between the series resonant frequency and the reference resonant frequency, as well as the difference between the measured quality factor and the reference quality factor.

[0118] Regarding the frequency difference, if the difference is not positive (i.e., the difference is less than or equal to zero, indicating that the resonant frequency of the measured coil is not higher than the reference value), or if the difference is positive but does not exceed the preset first deviation threshold (i.e., the frequency offset is within the system's allowable error range), then the non-short-circuit condition in terms of frequency is met.

[0119] Regarding the quality factor difference, if the difference is not negative (i.e., the difference is greater than or equal to zero, indicating that the quality factor of the tested coil is not lower than the reference value), or if the difference is negative but does not exceed the preset second deviation threshold (i.e., the decrease in quality factor is within the system's allowable error range), then the non-short-circuit condition for quality factor is met.

[0120] Because inter-turn short circuit faults reduce coil inductance, leading to an increase in resonant frequency, and also increase circuit losses, resulting in a decrease in the quality factor, determining the presence of an inter-turn short circuit requires both the frequency difference and the quality factor difference to exceed thresholds in a specific direction. When either the frequency difference condition (the difference is not positive or does not exceed the first deviation threshold) or the quality factor difference condition (the difference is not negative or does not exceed the second deviation threshold) is met, it indicates that the electrical parameter changes of the tested coil do not meet the criteria for an inter-turn short circuit. In this case, the control unit determines that there is no inter-turn short circuit in the tested coil.

[0121] If the difference between the series resonant frequency and the reference resonant frequency does not exceed the first deviation threshold, and the difference between the measured quality factor and the reference quality factor does not exceed the second deviation threshold, the tested coil is determined to be qualified.

[0122] Through the embodiments of this application, a two-way criterion logic is constructed, which not only avoids the situation where a normal coil is misjudged as a fault due to fluctuations in a single parameter, but also ensures the reliability of the test results under complex working conditions through a dual verification mechanism of frequency and quality factor.

[0123] In some embodiments, obtaining the reference resonant frequency and reference quality factor of the coil under test includes: testing a reference coil of the same model as the coil under test to obtain the resonant frequency and quality factor of the reference coil; and using the resonant frequency and quality factor of the reference coil as the reference resonant frequency and reference quality factor of the coil under test, respectively.

[0124] In this embodiment, the reference coil is a qualified coil of the same model as the coil under test. For example, a coil that has been confirmed to be in good working order and whose model and specifications are completely consistent with the coil under test is selected in advance and connected to the test circuit of the testing device, so that the reference coil is connected in series with the fixed capacitor module to form a series resonant circuit.

[0125] A reference coil of the same model as the coil under test is tested to obtain its resonant frequency and quality factor. The control unit controls the power amplifier to output an adjustable excitation voltage to the series resonant circuit. By gradually adjusting the output frequency, the phase difference between the loop current and the excitation voltage is detected, and the output frequency corresponding to the minimum phase difference is recorded as the series resonant frequency of the reference coil. The control unit controls the power amplifier to increase the excitation voltage at this series resonant frequency, and determines the actual voltage across the reference coil in real time based on the attenuated voltage output from the high-voltage divider, until the actual voltage reaches the preset target test voltage. At this point, the control unit calculates the ratio of the actual voltage to the excitation voltage and uses this ratio as the quality factor of the reference coil.

[0126] The resonant frequency and quality factor of the reference coil are used as the reference resonant frequency and reference quality factor of the coil under test, respectively. For example, the control unit stores the resonant frequency and quality factor of the reference coil obtained from the test in its internal storage module (such as a database) and establishes a correspondence with the model identification of the coil.

[0127] When it is necessary to perform inter-turn short circuit detection on the same model of coil under test, the control unit directly calls the corresponding data of that model from the storage module and defines them as the reference resonant frequency and reference quality factor of the coil under test, thereby providing a benchmark for subsequent parameter comparison and fault condition determination.

[0128] By using test data from a reference coil of the same model as a benchmark, this application provides an accurate and reliable basis for comparing the series resonant frequency and quality factor, thereby improving the accuracy and consistency of the inter-turn short circuit detection results.

[0129] In some embodiments, after the power amplifier increases the excitation voltage at the series resonant frequency, the method further includes: if, after a preset boosting time, the actual voltage across the coil under test still fails to reach the preset target test voltage, determining that the coil under test has resonant point drift or damage.

[0130] In this embodiment, the preset boost duration is a pre-set time length within the control unit to ensure sufficient time interval between the start of increasing the excitation voltage and the achievement of stable output by the power amplifier, for example, set to 5 seconds or 10 seconds. When the control unit controls the power amplifier to start increasing the excitation voltage at the series resonant frequency, its internal timing module synchronously starts timing.

[0131] The actual voltage is the real-time voltage across the coil under test, calculated from the attenuated voltage output by the high-voltage divider according to a fixed voltage division ratio. The target test voltage is the desired coil test voltage value, such as 2500V, pre-stored in the control unit.

[0132] During the timing process, the control unit continuously monitors the decaying voltage through the voltage measurement unit and calculates the actual voltage in real time. When the timing reaches the preset boost duration, the control unit compares the actual voltage with the target test voltage. If the actual voltage is still lower than the target test voltage at this time, and the power amplifier has already output its maximum output excitation voltage (or has reached the system's set boost limit), it indicates that the circuit has failed to raise the coil voltage to the target value as expected in the resonant state.

[0133] If the actual voltage across the coil under test cannot reach the target test voltage, it corresponds to the following two fault states: First, the actual inductance of the coil under test has changed, causing its true series resonant frequency to deviate from the previously recorded series resonant frequency, resulting in resonant point drift, which makes it impossible for the circuit to maintain the resonant state or weaken the resonant boost effect at the current frequency; Second, the coil under test is severely damaged, such as a severe inter-turn short circuit, which leads to an increase in the equivalent resistance of the circuit and a decrease in the quality factor, thus making it impossible to establish the required coil voltage.

[0134] When the actual voltage fails to reach the target test voltage, the control unit determines that the coil under test has a resonant point drift or damage, and generates a fault prompt message to be output to the human-machine interface to prompt the operator to check the coil connection or re-perform the tuning operation.

[0135] Through the embodiments of this application, by introducing a preset duration as a judgment window during the voltage boosting stage, when the actual voltage of the coil under test cannot reach the target test voltage within a limited time, it can promptly identify whether there is resonance point drift or damage, thereby terminating invalid excitation in the early stage of testing and avoiding energy waste and equipment damage.

[0136] In some embodiments, after adjusting the output frequency of the power amplifier to minimize the phase difference between the loop current and the excitation voltage, the method further includes: determining that the coil under test has not entered a resonant state when the phase difference between the loop current and the excitation voltage is greater than a preset phase threshold and the actual voltage across the coil under test is lower than a preset target test voltage.

[0137] Figure 5 A typical waveform diagram at resonance according to an embodiment of this application is schematically shown. Three sinusoidal waveforms are shown: power supply voltage U1, loop current I1, and coil voltage U2. In the figure, the horizontal axis represents time, and the vertical axis represents signal amplitude. The waveform of coil voltage U2 leads the loop current I1 by 90°, and the amplitude of coil voltage U2 is significantly higher than that of power supply voltage U1. This reflects the impedance characteristics and boost effect at series resonance.

[0138] In this embodiment, the preset phase threshold is a phase angle limit set in advance inside the control unit, which is used to determine whether the circuit is in or close to a series resonance state.

[0139] Under the desired series resonance state, the phase difference between the loop current and the excitation voltage is theoretically zero. When the actual measured phase difference is greater than the preset phase threshold, it indicates that the circuit exhibits obvious inductive or capacitive characteristics and does not meet the resonance condition. The target test voltage is the pre-configured high voltage value expected to be established across the coil under test.

[0140] After the tuning process is completed, the control unit reads the final phase difference recorded at this time and obtains the actual voltage across the tested coil calculated based on the attenuation voltage and the voltage division ratio of the high voltage divider.

[0141] If the phase difference between the loop current and the excitation voltage is greater than a preset phase threshold, and the actual voltage across the coil under test is lower than the preset target test voltage, the control unit determines that the coil under test has not entered a resonant state. At this time, the control unit can generate corresponding prompts to instruct the operator to check the frequency parameter settings or the coil connection status.

[0142] Figure 6 A test control flowchart according to an embodiment of this application is illustrated schematically.

[0143] like Figure 6 As shown, the control power amplifier outputs an initial excitation voltage to the series resonant circuit. The voltage and current measurement units detect the power supply voltage and loop current waveforms respectively, and calculate their phase difference. It is determined whether this phase difference is less than a preset threshold; if so, the current frequency is recorded as the resonant frequency, and the frequency is fine-tuned to minimize the phase difference. The control power amplifier then outputs at the determined resonant frequency and enters the boost test phase; if not, the frequency step is adjusted. Next, it is determined whether the frequency exceeds the termination frequency. If it does not exceed the termination frequency, the excitation voltage is output again; if it exceeds the termination frequency, it is determined that no resonant point has been found, and an error is reported, ending the test.

[0144] Through the embodiments of this application, after locking the minimum phase difference, a verification is added. When the phase difference is greater than the preset phase threshold and the actual voltage is lower than the target test voltage, it is determined that the coil under test has not entered the resonance state. This allows for the identification of wiring abnormalities or coil faults before formal voltage boosting, avoiding data interference from non-resonant conditions in subsequent judgments and improving the reliability of the detection process.

[0145] In some embodiments, the current measuring unit is a current clamp; after detecting the loop current of the series resonant circuit by the current measuring unit, the method further includes: determining that the loop current exceeds the measurement range of the current clamp in the case of waveform distortion of the loop current.

[0146] In this embodiment, the current clamp is a current sensor based on the principle of electromagnetic induction. Its jaws can open and close to clamp the outside of the conductor of the series resonant circuit, coupling the magnetic field changes around the conductor in a non-contact manner, thereby detecting the loop current of the series resonant circuit.

[0147] After the loop current of the series resonant circuit is detected by the current measurement unit, the control unit acquires the loop current signal output by the current clamp. For example, the loop current signal is transmitted to the data acquisition module of the oscilloscope or control unit for display in waveform form or digital storage.

[0148] Waveform distortion of the loop current refers to the unexpected distortion of the signal waveform output by the current clamp, such as clipping at the top or bottom of a sine wave (i.e., top or bottom clipping). The current clamp has a rated measurement range (i.e., range). When the actual loop current in the series resonant circuit exceeds the upper limit of the current clamp's range, the magnetic core inside the current clamp saturates, causing its output signal to no longer maintain a linear proportional relationship with the actual current, thus resulting in waveform distortion.

[0149] If the loop current waveform is distorted, the control unit determines that the loop current exceeds the measurement range of the current clamp. At this point, a corresponding prompt message is generated to instruct the operator to replace the current clamp with one having a higher measurement range, ensuring the accuracy of the measurement data.

[0150] In this embodiment, the loop current of the series resonant circuit is detected by a current clamp, and the loop current is determined to be outside the measurement range of the current clamp based on the waveform distortion of the loop current after detection. By utilizing the characteristic that the magnetic core saturation of the current clamp will cause the output waveform distortion when overloaded, it is possible to identify in real time that the measurement unit is in an over-range nonlinear working state, thereby avoiding the impact of current data distortion on the subsequent calculation of the phase difference between the loop current and the excitation voltage and the resonant frequency locking.

[0151] This application aims to solve the problems of high equipment cost, insufficient test sensitivity, and lack of self-verification methods in coil inter-turn short-circuit testing, and has the following beneficial effects:

[0152] Utilizing the principle of series resonance, a series resonant circuit is formed between a fixed capacitor module and the coil under test. The control unit controls a power amplifier to output a frequency-adjustable excitation voltage to this series resonant circuit. In the resonant state, the actual voltage across the coil under test is determined in real-time based on the attenuated voltage output from the high-voltage divider; this actual voltage is significantly higher than the excitation voltage output by the power amplifier. Therefore, only a relatively low excitation voltage (e.g., 200V) is required to establish the necessary high test voltage (e.g., 2500V) across the coil under test, thereby significantly reducing the output capacity requirements of the power amplifier and decreasing the size and cost of the equipment.

[0153] A short circuit between turns will cause a slight decrease in the inductance of the coil under test. Since the series resonant frequency is determined by both the inductance and the capacitance of the fixed capacitor module, a decrease in inductance will cause the series resonant frequency to increase. Simultaneously, the increased losses caused by the short circuit will lead to a decrease in the circuit quality factor (quality factor Q is the ratio of the actual voltage across the coil under test to the excitation voltage). The control unit can sensitively detect minute short circuit faults by accurately measuring the series resonant frequency and quality factor and comparing them with a reference resonant frequency and a reference quality factor.

[0154] The control unit's storage module stores reference coil profile data corresponding to different models of the coil under test. This profile data includes parameters such as reference resonant frequency and reference quality factor. During routine testing, the control unit compares the real-time detected series resonant frequency and measured quality factor with the reference profile data to quickly determine whether there is an inter-turn short circuit in the coil under test. It can also be used to verify whether the testing device itself is functioning correctly.

[0155] During testing, the power amplifier outputs a low excitation voltage, with the high voltage only appearing across the coil under test. A high-voltage divider is connected in parallel across the coil, and its output attenuated voltage is proportional to the voltage across the coil. The voltage measurement unit indirectly obtains the coil voltage by detecting this attenuated voltage, achieving electrical isolation between the high-voltage side and the measurement side, ensuring operator safety. Furthermore, the control unit controls the power amplifier to gradually increase the excitation voltage at the series resonant frequency until the actual voltage reaches the target test voltage. This gradual voltage increase mechanism prevents voltage surges from damaging the coil insulation.

[0156] The control unit is connected to the power amplifier, current measurement unit, and voltage measurement unit. It can automatically perform frequency adjustment to search for the series resonant frequency, control the increase of the excitation voltage, collect loop current and voltage data, calculate the quality factor, and automatically determine the inter-turn short circuit state based on the comparison results. The above process reduces manual intervention and realizes the automation of testing.

[0157] Figure 7 A schematic diagram of a train according to an embodiment of this application is shown.

[0158] like Figure 7 As shown, a coil-to-turn short-circuit detection device can be deployed on the train 700. This coil-to-turn short-circuit detection device can be as described in any of the embodiments described above.

[0159] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram or flowchart, and combinations of blocks in a block diagram or flowchart, may be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0160] Those skilled in the art will understand that the features described in the various embodiments of this application can be combined or combined in various ways, even if such combinations or combinations are not explicitly described in this application. In particular, the features described in the various embodiments of this application can be combined and / or combined in various ways without departing from the spirit and teachings of this application. All such combinations and / or combinations fall within the scope of this application.

[0161] The embodiments of this application have been described above. However, these embodiments are merely illustrative and not intended to limit the scope of this application. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. Without departing from the scope of this application, those skilled in the art can make various substitutions and modifications, all of which should fall within the scope of this application.

Claims

1. A coil turn-to-turn short-circuit detection device, characterized in that, include: A power amplifier is used to output a frequency-adjustable excitation voltage to the coil under test. A fixed capacitor module is connected in series between the power amplifier and the coil under test, and together with the coil under test, they form a series resonant circuit. A high-voltage divider is connected in parallel across the two ends of the coil under test to output an attenuated voltage proportional to the voltage across the coil under test. A current measuring unit is connected in series in the series resonant circuit to detect the loop current of the series resonant circuit. A voltage measurement unit is connected to the output terminal of the power amplifier and the output terminal of the high voltage divider, respectively, and is used to detect the excitation voltage and the attenuation voltage, respectively. The control unit is connected to the power amplifier, the current measurement unit and the voltage measurement unit respectively, and is used to control the power amplifier to output a frequency-adjustable excitation voltage to the series resonant circuit, and to detect the inter-turn short circuit state of the coil under test based on the loop current, the excitation voltage and the attenuation voltage.

2. The coil turn-to-turn short-circuit detection device according to claim 1, characterized in that, The fixed capacitor module includes multiple fixed capacitors and at least one switch; The plurality of fixed capacitors are connected to the series resonant circuit through the at least one switch to match the tested coils with different inductance values.

3. The coil turn-to-turn short-circuit detection device according to claim 1, characterized in that, The current measurement unit includes a current clamp or a current transformer; The current clamp or the current transformer is connected in series in the series resonant circuit for detecting the loop current of the series resonant circuit in a non-contact or contact manner.

4. The coil turn-to-turn short-circuit detection device according to claim 1, characterized in that, The voltage measurement unit includes an oscilloscope with a first channel, a second channel, and a third channel; The first channel is connected to the current measurement unit and is used to detect the first waveform signal of the loop current. The second channel is connected to the output terminal of the power amplifier and is used to detect the second waveform signal of the excitation voltage; The third channel is connected to the output terminal of the high-voltage divider and is used to detect the third waveform signal of the attenuated voltage.

5. A method for detecting inter-turn short circuits in a coil, applied to the inter-turn short circuit detection device according to any one of claims 1-4, characterized in that, The method includes: The control power amplifier outputs an adjustable excitation voltage to the series resonant circuit composed of a fixed capacitor module and the coil under test. The loop current of the series resonant circuit is detected by the current measurement unit, and the excitation voltage and the attenuated voltage output by the high voltage divider connected in parallel across the two ends of the coil under test are detected by the voltage measurement unit. By adjusting the output frequency of the power amplifier, the phase difference between the loop current and the excitation voltage is minimized, and the output frequency of the power amplifier when the phase difference is minimized is recorded as the series resonant frequency of the coil under test. The power amplifier is controlled to increase the excitation voltage at the series resonant frequency, thereby increasing the actual voltage across the coil under test; the actual voltage across the coil under test is determined in real time based on the attenuation voltage until the actual voltage reaches the target test voltage; The inter-turn short-circuit state of the coil under test is detected based on the excitation voltage, the actual voltage, and the series resonant frequency.

6. The coil turn-to-turn short-circuit detection method according to claim 5, characterized in that, The step of adjusting the output frequency of the power amplifier to minimize the phase difference between the loop current and the excitation voltage, and recording the output frequency of the power amplifier at which the phase difference is minimized as the series resonant frequency of the coil under test, includes: Set the initial output frequency of the power amplifier; The output frequency is gradually adjusted according to a preset frequency step size, and at each output frequency, the loop current is detected by the current measurement unit, and the excitation voltage is detected by the voltage measurement unit. Determine the phase difference between the loop current and the excitation voltage, and record the output frequency of the power amplifier when the phase difference is minimum as the series resonant frequency of the coil under test.

7. The coil turn-to-turn short-circuit detection method according to claim 5, characterized in that, The step of determining the actual voltage across the tested coil in real time based on the attenuated voltage includes: According to the voltage division ratio of the high voltage divider, the attenuation voltage is proportionally converted to determine the actual voltage across the coil under test, wherein the voltage division ratio is the ratio of the voltage across the coil under test to the attenuation voltage.

8. The coil turn-to-turn short-circuit detection method according to claim 5, characterized in that, The method of detecting the inter-turn short-circuit state of the coil under test based on the excitation voltage, the actual voltage, and the series resonant frequency includes: Obtain the reference resonant frequency and reference quality factor of the coil under test; The measurement quality factor of the coil under test is determined based on the ratio of the actual voltage across the coil under test to the excitation voltage. The series resonant frequency and the measured quality factor are compared with the reference resonant frequency and the reference quality factor, respectively. If the difference between the series resonant frequency and the reference resonant frequency is positive and exceeds the first deviation threshold, and the difference between the measured quality factor and the reference quality factor is negative and exceeds the second deviation threshold, it is determined that the tested coil has an inter-turn short circuit.

9. The coil turn-to-turn short-circuit detection method according to claim 8, characterized in that, After comparing the series resonant frequency and the measured quality factor with the reference resonant frequency and the reference quality factor, respectively, the method further includes: If the difference between the series resonant frequency and the reference resonant frequency is not positive or does not exceed the first deviation threshold, or if the difference between the measured quality factor and the reference quality factor is not negative or does not exceed the second deviation threshold, it is determined that the tested coil does not have an inter-turn short circuit.

10. The coil turn-to-turn short-circuit detection method according to claim 8, characterized in that, The process of obtaining the reference resonant frequency and reference quality factor of the coil under test includes: A reference coil of the same model as the coil under test is tested to obtain the resonant frequency and quality factor of the reference coil. The resonant frequency and quality factor of the reference coil are used as the reference resonant frequency and reference quality factor of the coil under test, respectively.

11. The coil turn-to-turn short-circuit detection method according to claim 5, characterized in that, After controlling the power amplifier to increase the excitation voltage at the series resonant frequency, the method further includes: If, after a preset voltage boosting time, the actual voltage across the coil under test still fails to reach the preset target test voltage, it is determined that the coil under test has resonant point drift or damage.

12. The coil turn-to-turn short-circuit detection method according to claim 5, characterized in that, After adjusting the output frequency of the power amplifier to minimize the phase difference between the loop current and the excitation voltage, the method further includes: If the phase difference between the circuit current and the excitation voltage is greater than a preset phase threshold, and the actual voltage across the coil under test is lower than a preset target test voltage, it is determined that the coil under test has not entered a resonant state.

13. A train, characterized in that, include: The coil turn-to-turn short circuit detection device according to any one of claims 1 to 4.

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