Bipolar pulse generator for transformer winding deformation diagnosis and control method thereof

Abstract

The embodiment of the invention discloses a bipolar pulse generator for transformer winding deformation diagnosis and a control method thereof. The bipolar pulse generator comprises a plurality of single-stage discharge modules which can be cascaded, each single-stage discharge module comprises a charging module connected with the energy storage capacitor; the positive polarity discharge switch is connected with the energy storage capacitor and is used for forming a part of a positive polarity discharge path when the positive polarity discharge switch is switched on; the negative polarity discharge switch is connected with the energy storage capacitor and is used for forming a part of a negative polarity discharge path when the negative polarity discharge switch is switched on; the at least two commutation switches are connected with the energy storage capacitor, the positive polarity discharge switch and the negative polarity discharge switch in a matched manner and are used for selectively constructing positive and negative polarity pulse output paths and an energy feedback path; the control system is used for controlling the working time sequence of the control system so as to output bipolar pulses to the load from the positive or negative polarity discharge path and feed back residual energy in the load to the energy storage capacitor through the energy feedback path; the pulse waveform is flexible and adjustable, and the energy utilization rate is improved.

Description

Technical Field

[0001] This invention relates to the field of pulse generator technology, and in particular to a bipolar pulse generator for diagnosing transformer winding deformation and its control method. Background Technology

[0002] In the fields of power systems and high-voltage engineering, transformers, as core equipment for power transmission and voltage conversion, are crucial for the safe operation of power systems through performance testing and condition assessment. Because winding deformation faults have a cumulative effect, failure to detect and repair them in a timely manner can lead to other transformer failures and even serious inter-turn short-circuit faults, thereby severely impacting the safety and stability of the power transmission network.

[0003] Among them, the pulse injection method, as a novel online monitoring method for transformer winding deformation, has attracted great attention from scholars at home and abroad and has good application prospects.

[0004] Traditional pulse generators often employ fixed topologies based on Marx circuits or solid-state switches. Their output parameters (such as pulse amplitude, waveform, and repetition frequency) are limited by the inherent characteristics of the hardware design, resulting in insufficient flexibility and poor adaptability. In particular, with the diversification of transformer testing requirements in modern power systems (such as high-frequency transient response testing of new energy grid-connected transformers and multi-waveform impact testing of flexible DC converter transformers), traditional pulse generators can no longer meet the technical requirements in terms of waveform programmability and dynamic parameter adjustment range. Summary of the Invention

[0005] The main objective of this invention is to provide a bipolar pulse generator for diagnosing transformer winding deformation, enabling flexible adjustment of the pulse waveform.

[0006] To achieve the above objectives, this application provides a bipolar pulse generator for diagnosing transformer winding deformation, comprising multiple cascaded single-stage discharge modules; each single-stage discharge module includes an energy storage capacitor, a charging module, a positive discharge switch, a negative discharge switch, at least two commutator switches, and a control system, wherein:

[0007] The charging module is connected to the energy storage capacitor and is used to charge the energy storage capacitor.

[0008] The positive discharge switch is connected to the energy storage capacitor and is used to form part of the positive discharge path when it is turned on.

[0009] The negative polarity discharge switch is connected to the energy storage capacitor and is used to form part of the negative polarity discharge path when it is turned on.

[0010] The at least two commutation switches are connected in conjunction with the energy storage capacitor, the positive discharge switch, and the negative discharge switch to selectively construct a positive pulse output path, a negative pulse output path, and an energy feedback path.

[0011] The control system is connected to the charging module, the positive discharge switch, the negative discharge switch, and the commutation switch, and is used to control their operating timing to output bipolar pulses to the load from the positive discharge path or the negative discharge path, and to feed back the residual energy in the load to at least one of the energy storage capacitors through the energy feedback path.

[0012] This application also provides a bipolar pulse generator control method for transformer winding deformation diagnosis, applied to a bipolar pulse generator for transformer winding deformation diagnosis as described in the first aspect, the method comprising:

[0013] Step 1: Charge the energy storage capacitors in the multiple cascaded single-stage discharge modules through the charging module.

[0014] Step 2: According to the requirements of the preset pulse waveform, the working sequence of the positive polarity discharge switch, negative polarity discharge switch and the commutator switch in each single-stage discharge module is controlled by the control system to selectively conduct to form a positive polarity discharge path or a negative polarity discharge path, so as to output a pulse with preset polarity to the load.

[0015] Step 3: After the preset stage of the pulse output or after it ends, the control system controls the commutation switch and / or the positive discharge switch and the negative discharge switch to construct an energy feedback path and feed the residual energy in the load back to at least one of the energy storage capacitors.

[0016] This application provides a bipolar pulse generator and its control method for diagnosing transformer winding deformation. The bipolar pulse generator includes multiple cascaded single-stage discharge modules. Each single-stage discharge module includes: a charging module connected to an energy storage capacitor; a positive discharge switch connected to the energy storage capacitor, used to form part of a positive discharge path when turned on; a negative discharge switch connected to the energy storage capacitor, used to form part of a negative discharge path when turned on; and at least two commutator switches cooperating with the energy storage capacitor, the positive discharge switch, and the negative discharge switch. The system includes a connection for selectively constructing positive and negative polarity pulse output paths and an energy feedback path; a control system for controlling its operating timing to output bipolar pulses to the load from the positive or negative polarity discharge path, and to feed the residual energy in the load back to at least one energy storage capacitor through the energy feedback path; the bipolar pulse generator is based on a bidirectional pulse modulation architecture with decoupled positive / negative polarity circuits, combined with the alternating triggering timing control of dual switching devices in each discharge module, breaking through the physical limitations of traditional unipolar output, and can achieve flexible and adjustable pulse waveforms, thereby improving energy utilization. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] in:

[0019] Figure 1 This is a schematic diagram of the structure of a bipolar pulse generator for diagnosing transformer winding deformation provided in an embodiment of this application;

[0020] Figure 2 This is a schematic diagram of the structure of a single-stage discharge module provided in an embodiment of this application;

[0021] Figure 3 A schematic diagram of another bipolar pulse generator provided in this application embodiment;

[0022] Figure 4 A schematic flowchart illustrating a bipolar pulse generator control method for diagnosing transformer winding deformation, provided in an embodiment of this application;

[0023] Figure 5A A circuit diagram of the charging stage of a positive polarity long pulse width exponentially decaying wave output mode provided in an embodiment of this application;

[0024] Figure 5BA circuit diagram of the discharge stage of a positive polarity long pulse width exponentially decaying wave output mode provided for an embodiment of this application;

[0025] Figure 5C A circuit diagram of the freewheeling stage of a positive polarity long pulse width exponentially decaying wave output mode provided for an embodiment of this application;

[0026] Figure 5D A schematic diagram of the switching operation timing of a positive polarity long pulse width exponentially decaying wave output mode provided in an embodiment of this application;

[0027] Figure 6A A circuit diagram of the charging stage of a negative polarity long pulse width exponentially decaying wave output mode provided in an embodiment of this application;

[0028] Figure 6B A circuit diagram of the discharge stage of a negative polarity long pulse width exponentially decaying wave output mode provided in an embodiment of this application;

[0029] Figure 6C A circuit diagram of the freewheeling stage of a negative polarity long pulse width exponentially decaying wave output mode provided for an embodiment of this application;

[0030] Figure 6D This is a schematic diagram of the working timing of a negative polarity long pulse width exponentially decaying wave output mode switch provided in an embodiment of this application.

[0031] Figure 7A A circuit diagram of the power feeding stage of a positive short pulse width triangular linear wave output mode provided in an embodiment of this application;

[0032] Figure 7B A schematic diagram of the working timing of a positive polarity short pulse width triangular linear wave output mode switch provided in an embodiment of this application;

[0033] Figure 8A A circuit diagram of the power feeding stage of a negative polarity short pulse width triangular linear wave output mode provided for an embodiment of this application;

[0034] Figure 8B A schematic diagram of the working timing of a negative polarity short pulse width triangular linear wave output mode switch provided in an embodiment of this application;

[0035] Figure 9 This is a schematic diagram illustrating the relationship between a bipolar pulse current and its corresponding load voltage, provided as an embodiment of this application. Detailed Implementation

[0036] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0037] The terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.

[0038] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0039] The embodiments of this application are described below with reference to the accompanying drawings.

[0040] Please see Figure 1 This is a schematic diagram of the structure of a bipolar pulse generator for diagnosing transformer winding deformation, provided in an embodiment of this application.

[0041] like Figure 1 As shown, the bipolar pulse generator 100 for transformer winding deformation diagnosis includes multiple cascaded single-stage discharge modules. Figure 1 Only three are shown: single-stage discharge module 1, single-stage discharge module 2, and single-stage discharge module n; the rest are omitted.

[0042] Figure 2 This is a schematic diagram of a single-stage discharge module provided in an embodiment of this application.

[0043] like Figure 2 As shown, a single-stage discharge module 200 may include an energy storage capacitor 210, a charging module 220, a positive discharge switch 230, a negative discharge switch 240, a converter switch 251, a converter switch 252, and a control system 260, wherein:

[0044] The charging module 220 is connected to the energy storage capacitor 210 and is used to charge the energy storage capacitor 210.

[0045] The aforementioned positive discharge switch 230 is connected to the aforementioned energy storage capacitor 210 and is used to form part of the positive discharge path when it is turned on.

[0046] The aforementioned negative polarity discharge switch 240 is connected to the aforementioned energy storage capacitor 210 and is used to form part of the negative polarity discharge path when it is turned on.

[0047] The commutator switches 251 and 252 are connected in conjunction with the energy storage capacitor 210, the positive discharge switch 230, and the negative discharge switch 240 to selectively construct a positive pulse output path, a negative pulse output path, and an energy feedback path.

[0048] The control system 260 is connected to the charging module 220, the positive discharge switch 230, the negative discharge switch 240, and the commutator switches 251 and 252. It is used to control the working sequence of the control system to output bipolar pulses to the load from the positive discharge path or the negative discharge path, and to feed back the residual energy in the load to the energy storage capacitor through the energy feedback path. The energy storage capacitor can be the energy storage capacitor 210 or any one or more of the bipolar pulse generators.

[0049] The aforementioned single-stage discharge module 200 can be used as Figure 1 The diagram shows a single-stage discharge module in a bipolar pulse generator.

[0050] In one alternative embodiment, the charging module 220 includes a DC power supply, a current-limiting resistor, and a charging switch controlled by the control system 260, for adjusting the charging voltage or charging amount of the energy storage capacitor 210.

[0051] In one alternative embodiment, the positive discharge switch 230 and the negative discharge switch 240 are insulated gate bipolar transistors, and the commutation switch 251 and the commutation switch 252 are silicon carbide metal oxide semiconductor field-effect transistors.

[0052] In an optional implementation, the energy feedback path is achieved by the control system 260 controlling the anti-parallel diodes of the converter switch and the positive discharge switch 230 or the negative discharge switch 240 to conduct during a preset energy feeding phase, thereby feeding the residual energy in the load back to the energy storage capacitor.

[0053] Further optionally, the energy feedback path includes a bidirectional DC / DC converter connected between the load and the energy storage capacitor 210, for actively feeding back residual energy from the load to the energy storage capacitor 210.

[0054] This application embodiment develops a directional feedback technology for residual load energy. Through a bidirectional DC / DC converter and a multi-port capacitor matrix in the front-end energy feedback circuit, the residual electrical energy in the discharged load is fed back to the upper-level energy storage capacitor (for maintaining the current pulse sequence) or the lower-level pre-charge capacitor (for the next pulse cycle). This can be understood as a switching combination to realize the conversion into the main energy feedback mechanism, which improves energy utilization compared to traditional solutions.

[0055] Figure 3 This is a schematic diagram of another bipolar pulse generator provided in an embodiment of this application. The bipolar pulse generator in this embodiment is a modular multi-stage discharge and energy feedback bipolar pulse generator, suitable for online diagnosis of transformer winding deformation.

[0056] like Figure 3 As shown, each discharge unit can be considered to consist of a positive polarity circuit and a negative polarity circuit. Based on the description of the foregoing embodiments, the charging module is respectively powered by a DC power supply U. dc1 Together with the current-limiting resistor R1, the charging module is connected via diode D. 1n Power is supplied to the positive and negative polarity circuit capacitors. The power supply circuit module is powered by power supply switch S. n1 (Positive polarity discharge switch), S n2 (Negative polarity discharge switch) and converter switch P n1 P n2 constitute.

[0057] The basic structure of the discharge functional unit in a single-stage discharge module consists of a discharge capacitor C. n1 Discharge switch S n1 S n2 commutator switch P n1 P n2 and charging diode D 1n Charging switch M n1 Composition. Based on the transformer's load characteristics, the load circuit can be represented by an inductor L (Load) and a resistor R. Positive and negative polarity pulse outputs are controlled by a discharge switch S. n1 S n2 and converter switch P n1 P n2 Joint control, via switching discharge switch S n1 S n2 and converter switch P n1 P n2The timing state controls the output waveform and intensity of the pulse.

[0058] Based on the transformer's load characteristics, positive and negative polarity pulse outputs are transmitted through discharge switch S. n1 S n2 and converter switch P n1 P n2 Joint control, via switching discharge switch S n1 S n2 and converter switch P n1 P n2 The timing state controls the pulse output waveform and intensity. The SiC MOSFET is the charging switch Mn1, and the rest are IGBTs.

[0059] Based on the aforementioned circuit, this application also provides a bipolar pulse generator control method for diagnosing transformer winding deformation.

[0060] Figure 4 This is a flowchart illustrating a bipolar pulse generator control method for diagnosing transformer winding deformation, provided in an embodiment of this application. Figure 4 As shown, this method can be applied to Figure 3 The method may include: a bipolar pulse generator as shown;

[0061] 401. Charge the energy storage capacitors in multiple cascaded single-stage discharge modules through the charging module;

[0062] 402. According to the requirements of the preset pulse waveform, the working sequence of the positive polarity discharge switch, negative polarity discharge switch and commutator switch in each single-stage discharge module is controlled by the control system to selectively conduct to form a positive polarity discharge path or a negative polarity discharge path, so as to output a pulse with preset polarity to the load.

[0063] 403. During or after the preset stage of the above pulse output, the above control system controls the above commutation switch and / or the above positive discharge switch and the above negative discharge switch to construct an energy feedback path and feed the residual energy in the above load back to at least one of the above energy storage capacitors.

[0064] In one optional implementation, the bipolar pulse generator for transformer winding deformation diagnosis includes:

[0065] Positive polarity long pulse width exponentially decaying wave output mode, negative polarity long pulse width exponentially decaying wave output mode, positive polarity short pulse width triangular linear wave output mode, and negative polarity short pulse width triangular linear wave output mode.

[0066] In one optional implementation, step 2 above includes:

[0067] The above-mentioned control system controls the coordinated operation of the positive polarity discharge switch, the negative polarity discharge switch, and the commutation switch to generate a bipolar short pulse width triangular linear wave or a bipolar long pulse width exponentially decaying wave.

[0068] Optionally, when generating a triangular linear wave, the construction of the above energy feedback path includes:

[0069] After the discharge switch of the corresponding polarity is turned off, at least one commutator switch is turned on, so that the load current is fed back to the energy storage capacitor through the anti-parallel diode of the turned-on commutator switch and the turned-off discharge switch.

[0070] In one optional implementation, for both the positive polarity long pulse width exponentially decaying wave output mode and the positive polarity short pulse width triangular linear wave output mode, step 2 includes:

[0071] The above-mentioned control system controls the positive discharge switch and the corresponding first commutator switch in each of the above-mentioned single-stage discharge modules to close, and the negative discharge switch and the corresponding second commutator switch to open, forming the above-mentioned positive discharge path, and each stage of capacitor is connected in series to discharge the above-mentioned load.

[0072] For the above-mentioned negative polarity long pulse width exponentially decaying wave output mode and the above-mentioned negative polarity short pulse width triangular linear wave output mode, step 2 above includes:

[0073] The control system controls the closing of the negative discharge switch and the corresponding second converter switch in each of the single-stage discharge modules, and the opening of the positive discharge switch and the corresponding first converter switch, forming the negative discharge path. Each stage of capacitor is connected in series to discharge the load.

[0074] Specifically, in the embodiments of this application, the corresponding pulse waveform can be selected for output as needed, and its positive and negative polarities can be realized by the control system controlling the positive polarity discharge switch, the negative polarity discharge switch, and the commutation switch.

[0075] This application proposes a bidirectional pulse modulation architecture based on the decoupling of positive / negative polarity circuits. Combined with the alternating triggering timing control of dual switching devices within each discharge module, it overcomes the physical limitations of traditional unipolar output, enabling programmable output of composite waveforms such as short-pulse-width triangular linear waves and long-pulse-width exponentially decaying waves. This application innovatively designs a cascaded expansion structure based on standardized discharge modules. Each discharge module adopts an integrated design of multiple switching units (such as a hybrid configuration of SiC MOSFETs and IGBTs) and distributed energy storage capacitors. The output voltage amplitude, magnetic field strength, and rate of change can be linearly adjusted by increasing or decreasing the number of modules.

[0076] For different modes, each mode contains three working stages: I. charging stage, II. discharging stage, and III. freewheeling stage / power feeding stage, which correspond to steps 1 to 3 above, respectively.

[0077] The working methods under different modes are described in detail below.

[0078] 1. Positive polarity long pulse width exponentially decaying wave output mode

[0079] Figure 5A This is a circuit diagram illustrating the charging phase of a positive polarity long-pulse-width exponentially decaying wave output mode, provided as an embodiment of this application. Figure 5A As shown:

[0080] Phase 1: Charging Stage: In this stage, the positive polarity circuit charging module charges each stage of capacitors. During this process, the discharge switch S... n1 S n2 It is in the off state, while the converter switch P n1 P n2 When the circuit is in the closed state, all capacitors are charged in parallel. During the charging phase, the charging voltage of each capacitor follows an exponential law. For a fixed capacitor voltage, the charging voltage can be determined by controlling the operating time of the charging switch Mn1, which can be achieved through timed on / off control.

[0081] Figure 5B This is a circuit diagram illustrating the discharge stage of a positive polarity long pulse width exponentially decaying wave output mode, provided as an embodiment of this application. Figure 5B As shown:

[0082] II. Discharge Stage: After the capacitor is fully charged, the main switches S of each discharge module in the positive polarity circuit... n1 and converter switch P n1 Close, commutator switch P n2 S n2 Disconnect, and the system enters the positive polarity discharge stage. At this time, if the positive polarity circuit is completely discharged, the module's main switch S... 11 -S n1 When conduction occurs, all capacitors in series discharge to the load, thus achieving a superposition of the output voltage by a factor of n. Within a short time, capacitor C... n1 It can be regarded as a constant pressure source.

[0083] The load current depends on the system output voltage. Therefore, under the condition that the load remains unchanged, the main switch S of each stage of the positive polarity discharge module can be adjusted. 1n The on-time and number of on-modules are used to control the load output magnetic field parameters.

[0084] Figure 5C This is a circuit diagram illustrating the freewheeling stage of a positive polarity long pulse width exponentially decaying wave output mode, provided as an embodiment of this application. Figure 5C As shown:

[0085] III. Freewheeling Stage: When the discharge task is completed, the positive polarity circuit main switch S... n1 and S n2 Disconnect, positive polarity circuit commutator switch P n1 and converter switch P n2 All loops are closed, forming a closed loop as shown in the figure.

[0086] Figure 5D This is a schematic diagram of the working timing of a positive polarity long pulse width exponentially decaying wave output mode switch provided in an embodiment of this application.

[0087] In the positive polarity long-pulse-width exponentially decaying wave output mode, the load energy will eventually be gradually consumed through the line resistance and load resistance, resulting in an exponential current tail with a long duration. The load temperature rises, and a pulsed magnetic field corresponding to the long-pulse-width exponentially decaying wave form is output from the load. The switching control timing of each stage is as follows: Figure 5D As shown.

[0088] 2. Negative polarity long pulse width exponentially decaying wave output mode

[0089] Figure 6A This is a circuit diagram illustrating the charging phase of a negative polarity long-pulse-width exponentially decaying wave output mode, as provided in an embodiment of this application. Figure 6A As shown:

[0090] Phase 1: Charging Stage: In this stage, the positive polarity circuit charging module charges each stage of capacitors. During this process, the discharge switch S... n1 S n2 It is in the off state, while the converter switch P n1 P n2 When the circuit is in the closed state, all capacitors in the circuit are charged in parallel. For a fixed capacitor voltage, the charging switch M can be controlled. n1 The charging voltage is determined by the action time.

[0091] Figure 6B This is a circuit diagram illustrating the discharge stage of a negative polarity long-pulse-width exponentially decaying wave output mode, provided as an embodiment of this application. Figure 6B As shown:

[0092] II. Discharge Stage: After the capacitor is fully charged, the main switches S of each discharge module in the negative polarity circuit... n2 and converter switch P n2 Close, commutator switch P n1 S n1 Disconnect, and the system enters the negative polarity discharge stage. At this time, if the entire negative polarity circuit is discharged, the module's main switch S... 12 -S n2When conduction occurs, all capacitors in series discharge to the load, thus achieving a superposition of the output voltage by a factor of n. Within a short time, capacitor C... n1 It can be regarded as a constant pressure source.

[0093] Similar to the positive polarity discharge mode, parameters such as the magnetic field strength and rate of change of the magnetic field output by the load depend on the system output voltage. Therefore, under the condition that the load remains unchanged, the main switch S of each stage of the negative polarity discharge module can be adjusted. n2 The on-time and number of on-modules are used to control the load output pulse related parameters.

[0094] Figure 6C This is a circuit diagram illustrating the freewheeling stage of a negative polarity long-pulse-width exponentially decaying wave output mode, provided as an embodiment of this application. Figure 6C As shown:

[0095] III. Freewheeling Stage: When the discharge task is completed, the negative polarity circuit main switch S... n1 and S n2 Disconnect, negative polarity circuit commutator switch P n1 and converter switch P n2 All loops are closed, forming a closed loop as shown in the figure.

[0096] Figure 6D This is a schematic diagram of the working timing of a negative polarity long pulse width exponentially decaying wave output mode switch provided in an embodiment of this application.

[0097] Similar to the positive polarity output mode, in the negative polarity long-pulse-width exponentially decaying wave output, the load energy will eventually be gradually consumed through the line resistance and load resistance, thus forming an exponential current tail with a longer current duration. The load temperature rises, and the load outputs a pulse magnetic field in the form of a long-pulse-width exponentially decaying wave. The timing of each stage of the switch control is as follows: Figure 6D As shown.

[0098] 3. Positive polarity short pulse width triangular linear wave output mode

[0099] The charging phase (Ⅰ) and discharging phase (ⅠⅠ) of the positive short-pulse-width triangular linear wave output mode are the same as those of the positive long-pulse-width exponentially decaying wave output mode, and will not be described again here.

[0100] Figure 7A This is a circuit diagram of the power feeding stage of a positive short pulse width triangular linear wave output mode provided in an embodiment of this application.

[0101] Phase I-I: If the discharge switch S is disconnected after the discharge phase of the positive polarity circuit has ended. n2 And at this time P n1 When in the off state, the load current will flow through the commutator switch P. n2 Discharge switch S n1Return to capacitors C at each stage 1n This allows for the recovery of excess energy from the load.

[0102] Figure 7B This is a schematic diagram of the working timing of a positive polarity short pulse width triangular linear wave output mode switch provided in an embodiment of this application.

[0103] In the positive short-pulse-width triangular linear wave output mode, most of the load energy can be returned to the capacitors at each stage through the power feeding circuit, while a small amount is dissipated through the load and line internal resistance, thus restoring the capacitor voltage and reducing the load temperature rise and the charging power requirements of the system. When the commutator switch is off, the voltage across the switch is stabilized at the voltage of a single-stage capacitor, ensuring that the switch is not broken down by the inductor voltage. Simultaneously, after commutation, the load voltage is also stabilized at the capacitor voltage, maintaining a linear falling edge magnetic field change rate, ultimately outputting a positive short-pulse-width triangular linear pulse wave to the load. The operating timing of each stage of the switch is as follows: Figure 7B As shown.

[0104] 4. Negative polarity short pulse width triangular linear wave output mode

[0105] The charging phase (Ⅰ) and discharging phase (ⅠⅠ) of the negative polarity short-pulse-width triangular linear wave output mode are the same as those of the negative polarity long-pulse-width exponentially decaying wave output mode, and will not be described again here.

[0106] Figure 8A This is a circuit diagram of the power feeding stage of a negative polarity short pulse width triangular linear wave output mode provided in an embodiment of this application.

[0107] like Figure 8A As shown, during the ⅠⅢ energy feeding stage: if the discharge switch S is disconnected after the positive polarity circuit discharge stage ends. n1 And at this time P n2 When in the off state, the load current will flow through the commutator switch P. n1 Discharge switch S n2 Return to capacitors C at each stage 1n This allows for the recovery of excess energy from the load.

[0108] Figure 8B This is a schematic diagram of the working timing of a negative polarity short pulse width triangular linear wave output mode switch provided in an embodiment of this application.

[0109] In the forward short-pulse-width linear waveform output mode, the pulse generator directionally transfers residual energy at the load end to the distributed energy storage unit through a multi-stage energy feedback path, significantly reducing energy loss caused by the internal resistance of the test circuit and achieving coordinated optimization of system charging power demand and operating temperature rise. During the turn-off process of the commutator, its port potential is dynamically clamped within the rated voltage threshold of the modular capacitor unit, effectively avoiding the risk of device breakdown caused by transient overvoltage of the inductive load. At the same time, based on the capacitor voltage tracking control strategy, the linear characteristics of the output waveform in the decay stage are maintained, ensuring the steep leading edge and controllable trailing edge characteristics of the pulse waveform in the transient response test of the transformer winding, providing high-precision excitation signals for scenarios such as insulation dielectric breakdown characteristic analysis and high-frequency impedance spectrum measurement, while taking into account both test efficiency and equipment safety protection requirements. The working sequence of each stage of the switch in this process is as follows: Figure 8B As shown.

[0110] Figure 9 This is a schematic diagram illustrating the relationship between a bipolar pulse current and its corresponding load voltage, provided as an embodiment of this application.

[0111] One characteristic of the modular multi-stage discharge and energy feedback bipolar pulse generator topology is that the more stages of the discharge modules, the higher the flexibility of the system's output magnetic field. To further describe and verify the topology's ability to control output parameters, tests were conducted on the constructed experimental platform. By adjusting the switching timing of each stage, a bipolar pulse current and its corresponding load voltage were output in the coil, such as... Figure 9 As shown, the horizontal axis represents time, and the vertical axis represents the coil current and coil voltage. Figure 9 The upper curve is the current curve, and the lower curve is the voltage curve.

[0112] In the field of transformer pulse injection method for winding deformation testing, traditional pulse generators suffer from the following technical bottlenecks:

[0113] 1. Limited waveform generation capability: Traditional solutions using semi-controlled devices such as gas spark gap switches and fast ignition tubes with fixed parameter circuits are limited by the rigid constraints of switching characteristics and circuit topology. They can only output oscillating or unipolar pulse waveforms, making it difficult to flexibly generate bipolar waveforms (such as bipolar short-pulse-width triangular linear waves and long-pulse-width exponentially decaying waves). This results in the inability to accurately control key parameters such as pulse intensity, polarity, and rate of change, which severely restricts the multi-condition simulation requirements in transformer winding transient response testing.

[0114] 2. Low energy efficiency: In a single pulse output process, traditional devices dissipate up to 40%-60% of the energy as Joule heat due to the internal resistance of the discharge load. This not only wastes energy but also causes excessive load temperature rise, leading to increased equipment size and complexity due to heat dissipation requirements in high-voltage testing scenarios.

[0115] 3. Insufficient scalability: Existing devices adopt a single-stage or fixed cascade structure, and the adjustment of parameters such as output voltage amplitude and pulse change rate depends on physical circuit reconstruction. It is impossible to achieve dynamic parameter adjustment through modular combination, which makes it difficult to meet the rapid parameter switching required for wideband impedance characteristic testing of power electronic transformers.

[0116] To address the aforementioned issues, this application proposes a bipolar pulse generator employing a dual-circuit architecture with independent positive and negative polarity control. Combined with the timing-coordinated control of two-stage discharge switches, it overcomes the limitations of traditional unipolar output and can generate various standard waveforms, including bipolar short-pulse-width triangular linear waves and long-pulse-width exponentially decaying waves, as well as custom-defined combinations. This application innovatively introduces a load-side energy feedback circuit. Through capacitor energy storage and a multi-stage energy transfer path design, residual load energy is fed back to the upstream or downstream energy storage capacitor, improving the overall system energy efficiency compared to traditional solutions.

[0117] In addition, each discharge module adopts a standardized dual-switch unit, and the output voltage can be linearly expanded by increasing or decreasing the number of modules, so as to realize continuous adjustment of pulse intensity and rate of change, and adapt to cross-scale applications from micro biological sample stimulation to large transformer winding testing.

[0118] To address the technical bottlenecks of traditional high-voltage pulse generators in electrical equipment testing, such as significant output waveform uniformity, limited parameter adjustment freedom, and severe energy loss at the load end, this application proposes a high-performance pulse generation technology based on bipolar collaborative control and a modular topology architecture. This technology overcomes the limitations of traditional unipolar output by using a decoupled energy storage and dynamic release mechanism of positive and negative polarity circuits, achieving accurate generation of bipolar high-voltage pulse waveforms. It innovatively introduces a multi-level energy circulation management circuit, utilizing the timing control of the converter switch to achieve directional feedback of residual load energy, effectively suppressing system temperature rise and improving energy utilization efficiency. Employing a parallel expansion design of standardized modules, combined with intelligent triggering logic algorithms, it can flexibly reconstruct pulse amplitude, waveform characteristics, and transient rate of change, meeting the high adaptability requirements for complex pulse sequences in scenarios such as transformer winding transient response testing and insulation dielectric multi-condition breakdown analysis, thus improving testing accuracy while ensuring the long-term stability and reliability of the equipment.

[0119] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0120] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A bipolar pulse generator for diagnosing transformer winding deformation, characterized in that, It includes multiple cascaded single-stage discharge modules; each single-stage discharge module includes an energy storage capacitor, a charging module, a positive discharge switch, a negative discharge switch, at least two commutator switches, and a control system, wherein: The charging module is connected to the energy storage capacitor and is used to charge the energy storage capacitor. The positive discharge switch is connected to the energy storage capacitor and is used to form part of the positive discharge path when it is turned on. The negative polarity discharge switch is connected to the energy storage capacitor and is used to form part of the negative polarity discharge path when it is turned on. The at least two commutation switches are connected in conjunction with the energy storage capacitor, the positive discharge switch, and the negative discharge switch to selectively construct a positive pulse output path, a negative pulse output path, and an energy feedback path. The control system is connected to the charging module, the positive discharge switch, the negative discharge switch, and the commutation switch, and is used to control their operating timing to output bipolar pulses to the load from the positive discharge path or the negative discharge path, and to feed back the residual energy in the load to at least one of the energy storage capacitors through the energy feedback path.

2. The bipolar pulse generator for transformer winding deformation diagnosis according to claim 1, characterized in that, The charging module includes a DC power supply, a current-limiting resistor, and a charging switch controlled by the control system, used to adjust the charging voltage or charging amount of the energy storage capacitor.

3. The bipolar pulse generator for transformer winding deformation diagnosis according to claim 1, characterized in that, The positive discharge switch and the negative discharge switch are insulated gate bipolar transistors, and the commutation switch is a silicon carbide metal oxide semiconductor field-effect transistor.

4. The bipolar pulse generator for transformer winding deformation diagnosis according to claim 1, characterized in that, The energy feedback path is achieved by the control system controlling the commutation switch and the anti-parallel diode of the positive or negative discharge switch to conduct during a preset energy feeding phase, thereby feeding the residual energy in the load back to the energy storage capacitor.

5. The bipolar pulse generator for transformer winding deformation diagnosis according to claim 1, characterized in that, The energy feedback path includes a bidirectional DC / DC converter connected between the load and the energy storage capacitor, which is used to actively feed the residual energy in the load back to the energy storage capacitor.

6. A bipolar pulse generator control method for diagnosing transformer winding deformation, characterized in that, The bipolar pulse generator for diagnosing transformer winding deformation according to any one of claims 1-5; the method includes: Step 1: Charge the energy storage capacitors in the multiple cascaded single-stage discharge modules through the charging module. Step 2: According to the requirements of the preset pulse waveform, the working sequence of the positive polarity discharge switch, negative polarity discharge switch and the commutator switch in each single-stage discharge module is controlled by the control system to selectively conduct to form a positive polarity discharge path or a negative polarity discharge path, so as to output a pulse with preset polarity to the load. Step 3: After the preset stage of the pulse output or after it ends, the control system controls the commutation switch and / or the positive discharge switch and the negative discharge switch to construct an energy feedback path and feed the residual energy in the load back to at least one of the energy storage capacitors.

7. The bipolar pulse generator control method for transformer winding deformation diagnosis according to claim 6, characterized in that, The bipolar pulse generator for transformer winding deformation diagnosis includes: Positive polarity long pulse width exponentially decaying wave output mode, negative polarity long pulse width exponentially decaying wave output mode, positive polarity short pulse width triangular linear wave output mode, and negative polarity short pulse width triangular linear wave output mode.

8. The bipolar pulse generator control method for transformer winding deformation diagnosis according to claim 7, characterized in that, Step 2 includes: The control system controls the coordinated operation of the positive discharge switch, the negative discharge switch, and the commutation switch to generate a bipolar short-pulse-width triangular linear wave or a bipolar long-pulse-width exponentially decaying wave.

9. The bipolar pulse generator control method for transformer winding deformation diagnosis according to claim 8, characterized in that, In step 3, when generating a triangular linear wave, the construction of the energy feedback path includes: After the discharge switch of the corresponding polarity is turned off, at least one commutator switch is turned on, so that the load current is fed back to the energy storage capacitor through the turned-on commutator switch and the anti-parallel diode of the turned-off discharge switch.

10. The bipolar pulse generator control method for transformer winding deformation diagnosis according to claim 7, characterized in that, For the positive polarity long pulse width exponentially decaying wave output mode and the positive polarity short pulse width triangular linear wave output mode, step 2 includes: The control system controls the positive discharge switch and the corresponding first commutator switch in each single-stage discharge module to close, and the negative discharge switch and the corresponding second commutator switch to open, forming the positive discharge path. Each stage of capacitor is connected in series to discharge the load. For the negative polarity long pulse width exponentially decaying wave output mode and the negative polarity short pulse width triangular linear wave output mode, step 2 includes: The control system controls the closing of the negative discharge switch and the corresponding second commutator switch in each single-stage discharge module, and the opening of the positive discharge switch and the corresponding first commutator switch, forming the negative discharge path. Each stage of capacitor is connected in series to discharge the load.

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