Layered insulation and voltage equalization method and system for high-frequency fast-charging transformer PCB winding

Abstract

The application provides a layered insulation and voltage equalization method and system for a high-frequency fast-charging transformer PCB winding, and particularly relates to the technical field of high-frequency power electronic transformer insulation. The method comprises the following steps: providing a plurality of independent charge injection electrodes in an insulation medium layer of a PCB winding, the electrodes being electrically isolated from a main power circuit; generating a modulation signal different from the working frequency of the main power circuit; monitoring the voltage change rate of a port, combining the modulation signal to generate a charge control pulse sequence synchronized with the switching action of the main power circuit; applying the sequence to the electrodes to inject charges into the insulation medium layer to offset the space charge separation in the voltage mutation stage; collecting dielectric characteristic parameters reflecting the state of the insulation medium layer, adjusting the modulation signal parameters and / or the charge amount of the charge control pulse sequence according to the comparison result of the dielectric characteristic parameters and a preset threshold value, solving the problem of local electric field distortion under high-frequency transient state, improving the transient electric field uniformity, inhibiting insulation aging, and prolonging the service life and operation reliability of the equipment.

Description

Technical Field

[0001] This invention relates to the field of insulation technology for high-frequency power electronic transformers, and more specifically, to a method and system for layered insulation and voltage equalization of PCB windings in a high-frequency fast-charging transformer. Background Technology

[0002] With the rapid development of power electronics technology towards higher frequencies and higher power densities, the performance of high-frequency fast-charging transformers, as core components of power conversion, is crucial. Using printed circuit board (PCB) windings has become the mainstream technology for achieving high-precision and miniaturized manufacturing of these transformers. However, the continuous increase in operating frequency and the intensification of voltage stress pose severe challenges to the multi-layer insulation structure of PCB windings under extreme electrical conditions. Especially under high-frequency square wave or pulse voltage excitation, the steep rate of voltage change (dv / dt) generates complex transient electric fields between winding layers and turns. This not only exacerbates localized electric field concentration but may also trigger deeper dielectric insulation problems, posing a potential threat to the long-term reliable operation of the transformer.

[0003] To address these challenges, existing technologies primarily focus on material improvement and structural optimization. For example, they employ insulating materials with higher dielectric strength and lower loss factors; add electrostatic shielding layers between windings to balance capacitance distribution; or optimize winding layout and number of turns to improve voltage gradients. Furthermore, external circuits such as Restricted Circuits (RCDs) are used to suppress voltage spikes. These methods alleviate macroscopic electric field inhomogeneity and overvoltage stress to some extent. However, these techniques generally emphasize optimizing the "static" or "steady-state" electric field distribution and externally clamping the voltage waveform. They lack effective monitoring and intervention mechanisms for the microscopic phenomenon of "dynamic accumulation and migration of space charge" within the PCB insulating dielectric under repeated high-frequency transient voltage impacts due to dielectric relaxation, interface polarization, and other physical processes. This internal charge accumulation distorts the ideal electric field distribution of the design, and its effects are cumulative and delayed, making it difficult to predict and eliminate using traditional methods. This becomes a hidden but crucial factor contributing to insulation performance degradation and even eventual failure.

[0004] In summary, how to solve the problem of local electric field distortion and long-term insulation reliability degradation caused by the dynamic accumulation of space charge inside the PCB winding insulation medium under high-frequency transient operating conditions is an urgent problem to be solved. Summary of the Invention

[0005] The main objective of this invention is to provide a layered insulation and voltage equalization method and system for PCB windings of high-frequency fast-charging transformers. This method aims to solve the technical problems of local electric field distortion and long-term insulation reliability degradation caused by the dynamic accumulation of space charge inside the insulation medium of PCB windings under high-frequency transient operating conditions. This significantly improves the uniformity of the transient electric field of the transformer insulation system under high-frequency repetitive pulse stress, effectively suppresses insulation aging caused by space charge accumulation, and ultimately extends the service life and operational reliability of the equipment under harsh operating conditions.

[0006] To achieve the above objectives, the present invention provides a method and system for layered insulation and voltage equalization of PCB windings of high-frequency fast-charging transformers.

[0007] This invention provides a method for layered insulation and voltage equalization of PCB windings in a high-frequency fast-charging transformer, the method comprising:

[0008] Multiple independent charge injection electrodes are disposed in the insulating dielectric layer of the PCB winding, and each charge injection electrode is electrically isolated from the main power circuit of the PCB winding.

[0009] A modulation signal is generated, the frequency of which is different from the operating frequency of the main power circuit;

[0010] The voltage change rate at the port of the PCB winding is monitored, and a charge control pulse sequence is generated based on the modulation signal and the voltage change rate. The timing of the charge control pulse sequence is synchronized with the switching action of the main power circuit.

[0011] The charge-controlled pulse sequence is applied to the corresponding charge injection electrode to inject charge into the insulating dielectric layer during the voltage change phase corresponding to the switching action. The polarity of the injected charge can counteract the space charge separation caused by the voltage change in the insulating dielectric layer.

[0012] Dielectric characteristic parameters reflecting the state of the insulating dielectric layer are collected, and based on the comparison results of the dielectric characteristic parameters with a preset threshold, the parameters of the modulation signal and / or the amount of injected charge of the charge-controlled pulse sequence are adjusted.

[0013] Specifically, the provision of multiple independent charge injection electrodes in the insulating dielectric layer of the PCB winding, wherein each charge injection electrode is electrically isolated from the main power circuit of the PCB winding, includes:

[0014] In the insulating dielectric layer, at a predetermined position between adjacent winding layers or in the insulating gap between the winding layer and the magnetic core, a metal foil is etched to form the charge injection electrode;

[0015] Electrical isolation is achieved by connecting the metal foil to a drive trace independent of the main power circuit through insulating vias.

[0016] Specifically, the generation of the modulation signal, wherein the frequency of the modulation signal is different from the operating frequency of the main power circuit, includes:

[0017] A square wave signal is generated using a separate signal generator as the modulation signal;

[0018] The frequency of the square wave signal is set to 1 / N of the operating frequency of the main power circuit, where N is an integer greater than 2.

[0019] Specifically, monitoring the voltage change rate at the port of the PCB winding includes:

[0020] The voltage waveform at the PCB winding port is acquired using a high-voltage differential probe;

[0021] The voltage waveform is input into a differentiating circuit to calculate the voltage change rate.

[0022] Specifically, the step of generating a charge-controlled pulse sequence based on the modulation signal and the voltage change rate, wherein the timing of the charge-controlled pulse sequence is synchronized with the switching action of the main power circuit, includes:

[0023] When the absolute value of the voltage change rate is detected to exceed a preset change rate threshold, a pulse generation enable signal is triggered.

[0024] During the period when the pulse generation enable signal is active, the modulation signal is converted into a pulse synchronized with the rising or falling edge of the switching action, forming the charge control pulse sequence.

[0025] Specifically, applying the charge-regulating pulse sequence to the corresponding charge injection electrode to inject charge into the insulating dielectric layer during the voltage change phase corresponding to the switching action includes:

[0026] The charge-controlled pulse sequence is received via a high-speed isolation driver;

[0027] The high-speed isolation driver converts the charge-controlled pulse sequence into a high-voltage isolation pulse and applies it to the corresponding charge injection electrode through the drive trace.

[0028] Specifically, the polarity of the injected charge can counteract the space charge separation caused by the voltage change in the insulating dielectric layer, including:

[0029] The polarity of the space charge induced in the insulating dielectric layer is determined based on the polarity of the voltage change.

[0030] The polarity of the charge modulation pulse sequence is controlled so that the charge injection electrode injects a charge with the opposite polarity to the space charge into the insulating dielectric layer.

[0031] Specifically, the acquisition of dielectric characteristic parameters reflecting the state of the insulating dielectric layer includes:

[0032] Partial discharge signals are acquired by an RF current sensor coupled to the PCB winding, and the repetition rate or average amplitude of the partial discharge signals is used as the dielectric characteristic parameter; or,

[0033] The dielectric loss tangent is measured using an LCR bridge when a test signal is applied to the PCB winding, and the dielectric loss tangent is used as the dielectric characteristic parameter.

[0034] Specifically, adjusting the parameters of the modulation signal and / or the injected charge amount of the charge-controlled pulse sequence based on the comparison result of the dielectric characteristic parameters and the preset threshold includes:

[0035] Compare the dielectric characteristic parameters with a first preset threshold;

[0036] When the dielectric characteristic parameter is greater than the first preset threshold, the frequency of the modulation signal is increased, and / or the amount of injected charge in the charge-controlled pulse sequence is increased;

[0037] When the dielectric characteristic parameter is less than or equal to the first preset threshold, the frequency of the modulation signal is maintained or decreased, and / or the injected charge of the charge-controlled pulse sequence is maintained or decreased.

[0038] Specifically, increasing the injected charge amount of the charge-controlled pulse sequence includes:

[0039] Increase the voltage amplitude of a single pulse in the charge-controlled pulse sequence.

[0040] This application provides a method and system for layered insulation and voltage equalization of PCB windings in high-frequency fast-charging transformers. The method first sets multiple independent charge injection electrodes, electrically isolated from the main power circuit, in the insulating dielectric layer of the PCB windings, generating a modulation signal with a frequency different from the main power circuit's operating frequency. By monitoring the port voltage change rate, a charge-controlled pulse sequence synchronized with the switching action of the main power circuit is generated in conjunction with the modulation signal and applied to the electrodes. During voltage abrupt changes, charges that can compensate for spatial charge separation are injected into the insulating dielectric layer. Simultaneously, dielectric characteristic parameters reflecting the state of the insulating dielectric layer are collected, and the amount of charge injected is adjusted based on comparisons with preset thresholds, either by adjusting the modulation signal parameters or the charge-controlled pulse sequence. This method solves problems such as local electric field distortion under high-frequency transients, improves the uniformity of the transient electric field in the insulation system, suppresses insulation aging, and extends equipment lifespan and operational reliability. Attached Figure Description

[0041] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0042] Figure 1 A schematic flowchart illustrating the layered insulation and voltage equalization method for the PCB windings of the high-frequency fast-charging transformer provided in this application.

[0043] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0045] The terms "first," "second," "third," "fourth," etc. (if present) in the specification and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein.

[0046] In this invention, the terms "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0047] This application provides a method and system for layered insulation and voltage equalization of PCB windings in high-frequency fast-charging transformers. The technical concept of this application focuses on the insulation problem of PCB windings in high-frequency fast-charging transformers. Multiple independent charge injection electrodes, electrically isolated from the main power circuit, are placed in the insulating dielectric layer of the PCB windings to generate a modulation signal with a frequency different from that of the main power circuit. The rate of change of the port voltage is monitored, and a charge-controlled pulse sequence synchronized with the switching action is generated and applied to the electrodes to inject charge during voltage abrupt changes, thus counteracting spatial charge separation. Dielectric characteristic parameters are collected, and the modulation signal parameters or the amount of injected charge are adjusted based on the comparison with preset thresholds to solve problems such as local electric field distortion, thereby improving insulation performance and equipment reliability.

[0048] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0049] Figure 1 The flowchart illustrates the layered insulation and voltage equalization method for the PCB windings of the high-frequency fast-charging transformer provided in this application. Figure 1 As shown, this embodiment provides a method for layered insulation and voltage equalization of the PCB windings of a high-frequency fast-charging transformer. The method includes:

[0050] S101: Multiple independent charge injection electrodes are provided in the insulating dielectric layer of the PCB winding, and each charge injection electrode is electrically isolated from the main power circuit of the PCB winding.

[0051] Specifically, the provision of multiple independent charge injection electrodes in the insulating dielectric layer of the PCB winding, wherein each charge injection electrode is electrically isolated from the main power circuit of the PCB winding, includes: etching a metal foil as the charge injection electrode in the insulating dielectric layer at a predetermined position between adjacent winding layers or at the insulation gap between the winding layer and the magnetic core; and connecting the metal foil to a drive trace independent of the main power circuit through insulating vias to achieve the electrical isolation.

[0052] The specific steps of implementation S101 include:

[0053] A multilayer PCB substrate with at least four conductive layers is selected, and the core insulating material of the multilayer PCB substrate is FR-4. From top to bottom, the first copper foil layer is defined as the primary winding layer, the second copper foil layer as the first charge injection electrode layer, the third copper foil layer as the secondary winding layer, and the fourth copper foil layer as the second charge injection electrode layer. Between the primary winding layer and the first charge injection electrode layer, between the first charge injection electrode layer and the secondary winding layer, and between the secondary winding layer and the second charge injection electrode layer, there are insulating dielectric layers made of FR-4 material. When performing PCB layout using electronic design automation software, the required spiral or gyratory winding patterns are drawn on the primary and secondary winding layers, respectively. Simultaneously, on the first charge injection electrode layer, a closed annular copper foil pattern with a linewidth of 0.5 mm is drawn around the outer periphery of the overlapping area projected vertically by the primary and secondary windings, serving as the first charge injection electrode; the same annular copper foil pattern is drawn at the same position on the second charge injection electrode layer, serving as the second charge injection electrode. These two ring-shaped electrode patterns are not electrically connected to any part of the primary or secondary winding patterns. Subsequently, in PCB manufacturing, the above-mentioned patterns are transformed into actual copper foil structures through pattern transfer and etching processes. Specifically, a photoresist is coated on the copper-clad laminate, and ultraviolet exposure is performed through a photomask with winding and electrode patterns. The unexposed parts of the photoresist are removed by a developing solution to form the resist pattern. Then, ferric chloride etching solution is used to etch away the copper foil not protected by the photoresist. Finally, sodium hydroxide solution is used to remove the remaining photoresist to form the required primary winding, secondary winding, and charge injection electrode. To connect the drive circuit, a 0.3 mm diameter through-hole is made on the PCB at the endpoint of the charge injection electrode pattern using a mechanical drilling process. This hole extends from the first charge injection electrode layer to the bottom surface of the PCB board, but before the inner wall of the hole is plated with copper to conduct, the hole is filled with solder resist ink to form an insulating via. Next, on the bottom layer of the PCB (a separate routing layer), a 0.2 mm wide copper trace is led out from the location of the insulating via as a drive trace, extending to the connector pads at the edge of the PCB. Complete electrical isolation is achieved between the drive trace, charge injection electrode, primary winding, and secondary winding through FR-4 insulating dielectric and insulating vias. After manufacturing, the insulation resistance between the charge injection electrode and the nearest primary or secondary winding is measured using a digital multimeter on a high resistance setting (range greater than 100 megohms), confirming a resistance greater than 1 gigaohm, thus verifying the effectiveness of the electrical isolation.

[0054] This step, through specific PCB lamination structure design, clear material selection (FR-4), detailed pattern layout rules (the ring electrode is located on the outer periphery of the winding projection overlap area), and standard PCB manufacturing and verification processes (pattern transfer etching, insulating via fabrication, high-resistance testing), physically constructs charge injection electrodes and drive traces that are completely electrically isolated from the main power circuit. This provides the necessary and reliable physical interface and structural foundation for the subsequent steps of precisely injecting controllable charges into the insulating dielectric layer to counteract space charges, ensuring the feasibility of the entire method at the hardware level.

[0055] S102: Generate a modulation signal, the frequency of which is different from the operating frequency of the main power circuit.

[0056] Specifically, generating a modulation signal, wherein the frequency of the modulation signal is different from the operating frequency of the main power circuit, includes: generating a square wave signal as the modulation signal through an independent signal generator; and setting the frequency of the square wave signal to 1 / N of the operating frequency of the main power circuit, where N is an integer greater than 2.

[0057] The specific steps of implementation S102 include:

[0058] The main power circuit is driven by switching transistors (such as MOSFETs or IGBTs) in a full-bridge or half-bridge topology, with an operating frequency f_sw of 200 kHz. A direct digital frequency synthesizer (DDS) chip, independent of the main power control chip, is used to generate the modulation signal. The DDS chip's reference clock input is connected to a 25 MHz temperature-compensated crystal oscillator. A control word is written to the DDS chip's register via a serial peripheral interface bus to configure its output waveform as a square wave, with the duty cycle fixed at 50%. The square wave frequency f_mod is set to one-quarter of the main power circuit's operating frequency f_sw, i.e., f_mod = f_sw / 4. Substituting N = 4 into the calculation, the modulation signal frequency f_mod is obtained as 50 kHz. Simultaneously, the peak voltage V_pp of the square wave signal is set to 3.3V via the DDS chip's amplitude control register to match the input level of subsequent digital logic circuits. After configuration, enable the output of the direct digital frequency synthesizer chip. A square wave signal with a stable frequency of 50 kHz, an amplitude of 3.3V, and a duty cycle of 50% can be obtained on the signal output pin of the direct digital frequency synthesizer chip. This signal is the modulation signal required for subsequent steps.

[0059] This step generates an independent modulation signal with a defined frequency and parameters by specifying the main power frequency (200kHz), selecting specific signal generation devices (direct digital frequency synthesizer chip and temperature-compensated crystal oscillator), clearly defining the ratio between the modulation signal and the main power frequency (N=4, resulting in 50kHz), and specifying the parameters of the square wave signal (50% duty cycle, 3.3V amplitude). This signal frequency has a definite difference (50kHz) from the main power frequency (200kHz). This difference forms the physical basis for subsequent "asynchronous, specific intervention," providing a core excitation source for generating a charge-controlled pulse sequence that can interact with high-frequency transient processes and thus precisely regulate the charge behavior within the medium. This ensures the targeted nature and effectiveness of the intervention, representing a key creative step that distinguishes it from the conventional approach of simply following the main frequency.

[0060] S103: Monitor the voltage change rate at the port of the PCB winding, and generate a charge control pulse sequence based on the modulation signal and the voltage change rate. The timing of the charge control pulse sequence is synchronized with the switching action of the main power circuit.

[0061] Specifically, monitoring the voltage change rate at the port of the PCB winding includes: acquiring the voltage waveform at the port of the PCB winding using a high-voltage differential probe; inputting the voltage waveform into a differentiating circuit to calculate the voltage change rate.

[0062] Specifically, the step of generating a charge-controlled pulse sequence based on the modulation signal and the voltage change rate, wherein the timing of the charge-controlled pulse sequence is synchronized with the switching action of the main power circuit, includes: triggering a pulse generation enable signal when the absolute value of the voltage change rate exceeds a preset change rate threshold; and converting the modulation signal into a pulse synchronized with the rising or falling edge of the switching action during the effective period of the pulse generation enable signal to form the charge-controlled pulse sequence.

[0063] The specific steps in step S103 during implementation include:

[0064] When monitoring the rate of change of voltage, connect the two test terminals of the high-voltage differential probe (e.g., with a bandwidth of 100MHz and a differential input voltage range of ±1000V) to the two ends of the primary side port of the PCB winding, respectively. Turn on the main power circuit, enabling the switching transistor to operate at 200kHz. The high-voltage differential probe transmits the acquired analog signal V_port(t) of the primary side port to ground to the signal conditioning circuit. The signal conditioning circuit consists of a voltage follower and an inverting differentiator circuit composed of an operational amplifier. After impedance matching of V_port(t), the voltage follower inputs the signal to the inverting differentiator circuit. In the inverting differentiator circuit, the inverting input of the operational amplifier receives V_port(t) through a 100pF capacitor C and is connected to the output of the operational amplifier through a 10kΩ feedback resistor R. The non-inverting input of the operational amplifier is grounded. The output voltage V_diff(t) of the inverting differentiator circuit is proportional to the derivative of the input voltage V_port(t), with the proportionality coefficient determined by the RC time constant, i.e., V_diff(t) = -RC * dV_port(t) / dt. The absolute value of V_diff(t) represents the voltage change rate |dV / dt|. V_diff(t) is then input into a threshold comparison circuit composed of a high-speed comparator. The non-inverting input of the high-speed comparator receives V_diff(t), and the inverting input is connected to an adjustable reference voltage source. The voltage value of this reference voltage source is set to V_th, corresponding to a preset rate of change threshold (dV / dt)_th = 10V / ns (calculated according to RC = 1e-6, V_th corresponds to -10mV). When |V_diff(t)| > V_th, i.e., |dV / dt| > 10V / ns, the output of the high-speed comparator transitions from logic low to logic high, generating a pulse generation enable signal EN. The EN signal and the 50kHz modulated signal MOD generated in step S102 are simultaneously input into the digital logic module of a field-programmable gate array (FPGA) chip. The FPGA chip also receives the DRV switch drive signal from the main power loop controller as a synchronization reference via an isolated digital input channel. Inside the digital logic module, the EN signal is first edge-detected and pulse-width extended to ensure it remains valid (high level) for at least 5ns after each event where |dV / dt| > 10V / ns. During the high level of the EN signal, a synchronization logic is initiated: a logical AND operation is performed on the MOD and DRV signals. Specifically, when the DRV signal is within a 2ns time window triggered by a rising edge (switch on) or falling edge (switch off), the MOD signal is allowed to pass through. Through this logic operation, the continuous 50kHz MOD square wave signal is converted into a narrow pulse sequence with a pulse width of 2ns, strictly aligned with the edges of the DRV signal. This narrow pulse sequence is the charge-controlled pulse sequence PULSE_SEQ.PULSE_SEQ is completely synchronized in timing with the switching action of the main power circuit.

[0065] This step quantifies the transient rate of change of the port voltage in real time using specific probes and circuits (high-voltage differential probe, RC differentiator circuit, high-speed comparator) and sets a clear action threshold (10V / ns). Further, through specific digital logic (synchronous AND gate logic within the FPGA), this threshold is used to determine the result (enable signal EN) and an independent modulation signal (MOD) to generate a charge-regulating pulse sequence precisely aligned in time (within a 2ns window) with the main switch's action edge. This series of operations ensures that the charge injection intervention is triggered only at critical moments when the voltage undergoes a drastic change (dV / dt exceeds the threshold), and that the injection pulse is strictly synchronized with the change moment. This achieves precise and timely targeted cancellation of the spatial charge separation process within the dielectric, serving as the core link between "state perception" and "active intervention." Its synchronization and conditional triggering characteristics are key to generating significant voltage equalization and insulation enhancement effects.

[0066] S104: The charge-controlled pulse sequence is applied to the corresponding charge injection electrode to inject charge into the insulating dielectric layer during the voltage change phase corresponding to the switching action. The polarity of the injected charge can counteract the space charge separation caused by the voltage change in the insulating dielectric layer.

[0067] Specifically, applying the charge-controlled pulse sequence to the corresponding charge injection electrode to inject charge into the insulating dielectric layer during the voltage change phase corresponding to the switching action includes: receiving the charge-controlled pulse sequence through a high-speed isolation driver; the high-speed isolation driver converting the charge-controlled pulse sequence into a high-voltage isolation pulse and applying it to the corresponding charge injection electrode through a drive trace.

[0068] Specifically, the polarity of the injected charge can counteract the space charge separation caused by the voltage change in the insulating dielectric layer, including: determining the polarity of the space charge induced in the insulating dielectric layer according to the polarity of the voltage change; controlling the polarity of the charge modulation pulse sequence so that the charge injection electrode injects a charge with the opposite polarity to the space charge into the insulating dielectric layer.

[0069] The specific steps in step S104 during implementation include:

[0070] The charge-controlled pulse sequence PULSE_SEQ generated in step S103 is input to a high-speed isolation driver module. The high-speed isolation driver module consists of a digital isolator chip and a subsequent MOSFET driver chip. PULSE_SEQ is first connected to the primary-side input pin of the digital isolator chip. Based on capacitive or magnetic isolation principles, the digital isolator chip generates a pulse signal PULSE_ISO on its secondary-side output pin that is perfectly timed with PULSE_SEQ but electrically isolated from the primary-side control circuit. The PULSE_ISO signal is then fed into the input of the MOSFET driver chip. The output stage of the MOSFET driver chip consists of a push-pull circuit, with its power supply pin connected to an adjustable DC voltage source V_DRV. The MOSFET driver chip amplifies the PULSE_ISO logic signal, converting it into a gate drive signal capable of rapidly driving the MOSFET switch; this signal is the high-voltage isolation pulse PULSE_HV. The amplitude of PULSE_HV is equal to the voltage value of V_DRV, and both its rise and fall times are less than 20 nanoseconds. PULSE_HV is transmitted and applied to the corresponding charge injection electrode within the PCB winding through the drive trace prepared in step S101. To inject charges of opposite polarity under different voltage abrupt changes, an H-bridge circuit composed of four N-channel MOSFETs is connected between the MOSFET driver chip and the charge injection electrode. The two inputs of the H-bridge circuit are connected to two auxiliary power supplies of opposite polarities: +V_HB (e.g., +100V) and -V_HB (e.g., -100V). The control logic of the H-bridge circuit is implemented by a field-programmable gate array (FPGA). The FPGA receives the voltage change rate signal V_diff(t) from the differential circuit output in step S103 and determines its polarity. When V_diff(t) > 0 (corresponding to a rise in the primary-side port voltage, i.e., a positive voltage abrupt change), the FPGA determines that the space charge polarity induced in the insulating dielectric layer is positive (i.e., positive charge accumulation). At this point, the field-programmable gate array (FPGA) generates H-bridge control logic such that when PULSE_HV is high, the H-bridge connects -V_HB (-100V) to the charge injection electrode and connects the ground potential to the return path of the drive trace, thereby injecting negative charge into the insulating dielectric layer. Conversely, when V_diff(t) < 0 (corresponding to a drop in primary-side port voltage, i.e., a negative voltage jump), the FPGA determines that the polarity of the space charge induced in the insulating dielectric layer is negative. In this case, the H-bridge is controlled to connect +V_HB (+100V) to the charge injection electrode when PULSE_HV is high, thereby injecting positive charge into the insulating dielectric layer.In this way, the charge injected into the insulating dielectric layer by the charge injection electrode during the voltage change phase corresponding to the switching action has a polarity that is always opposite to the polarity of the space charge induced in the insulating dielectric layer by the voltage change, thereby achieving a cancellation effect.

[0071] This step uses a specific high-speed isolation driver module (digital isolator and MOSFET driver) and a controlled H-bridge circuit to safely and reliably convert a logic pulse sequence into a high-voltage injection pulse with sufficient amplitude (e.g., ±100V) and speed (rise / fall time <20ns), and applies it precisely to the charge injection electrode through a preset drive trace. Its core innovation lies in determining the output voltage polarity of the H-bridge by judging the polarity of the voltage change rate in real time, thereby ensuring that the polarity of each injected charge is opposite to the predicted space charge polarity. This achieves active, real-time, and targeted neutralization of the space charge separation phenomenon inside the insulating medium. This is a key step in transforming the core inventive concept of "cancellation" into a concrete and implementable electrical operation, which directly determines the realization of voltage equalization and insulation enhancement effects.

[0072] S105: Collect dielectric characteristic parameters reflecting the state of the insulating dielectric layer, and adjust the parameters of the modulation signal and / or the injected charge amount of the charge-controlled pulse sequence based on the comparison results of the dielectric characteristic parameters and the preset threshold.

[0073] Specifically, the acquisition of dielectric characteristic parameters reflecting the state of the insulating dielectric layer includes: acquiring partial discharge signals through a radio frequency current sensor coupled to the PCB winding, and using the repetition rate or average amplitude of the partial discharge signals as the dielectric characteristic parameters; or, measuring the dielectric loss tangent value through an LCR measurement bridge when a test signal is applied to the PCB winding, and using the dielectric loss tangent value as the dielectric characteristic parameters.

[0074] Specifically, adjusting the parameters of the modulation signal and / or the injected charge of the charge-controlled pulse sequence based on the comparison result of the dielectric characteristic parameter and the preset threshold includes: comparing the dielectric characteristic parameter with a first preset threshold; when the dielectric characteristic parameter is greater than the first preset threshold, increasing the frequency of the modulation signal and / or increasing the injected charge of the charge-controlled pulse sequence; when the dielectric characteristic parameter is less than or equal to the first preset threshold, maintaining or decreasing the frequency of the modulation signal and / or maintaining or decreasing the injected charge of the charge-controlled pulse sequence.

[0075] Specifically, increasing the injected charge amount of the charge-controlled pulse sequence includes increasing the voltage amplitude of a single pulse in the charge-controlled pulse sequence.

[0076] The specific steps in step S105 during implementation include:

[0077] When acquiring dielectric characteristic parameters reflecting the state of the insulating dielectric layer, one of the following two methods can be selected. The first method couples an RF current sensor with an operating frequency range of 1MHz to 30MHz to the ground lead of the secondary winding port on the PCB. The RF current sensor converts the sensed high-frequency current signal into a voltage signal. This voltage signal passes through a bandpass filter with a center frequency of 10MHz and a bandwidth of 2MHz to suppress power frequency and switching frequency interference. The filtered signal is then fed into a peak detection and pulse counting circuit with an adjustable comparison level. The pulse counting circuit identifies pulses with amplitudes exceeding a set threshold (e.g., 10mV) as partial discharge pulses and uses a 1-second time-based counter to record the number of these pulses, obtaining the partial discharge repetition rate PD_Rate (unit: pulses / second), which is used as a dielectric characteristic parameter. Simultaneously, the peak detection circuit outputs the average amplitude of these pulses PD_Amp (unit: millivolts), as a candidate dielectric characteristic parameter. The second method involves connecting the primary side of the PCB winding to the test terminal of an LCR measurement bridge via a relay during the interval when the main power circuit is off. The LCR measurement bridge measures the equivalent parallel capacitance C_p and equivalent parallel resistance R_p across the PCB winding at a test frequency of 1kHz and a test voltage of 1V. The processor built into the LCR measurement bridge calculates the dielectric loss tangent using the formula tanδ = 1 / (2πf * R_p * C_p), where f is the test frequency of 1kHz and π is pi. The calculated tanδ value is used as the dielectric characteristic parameter. After obtaining the dielectric characteristic parameter (PD_Rate or tanδ), it is input into a microcontroller. The microcontroller internally stores a preset first threshold. Taking the partial discharge repetition rate PD_Rate as an example, the first preset threshold Th_PD is set to 100 pulses / second. The microcontroller performs a comparison operation: comparing the real-time measured value of PD_Rate with Th_PD. When PD_Rate is greater than Th_PD, the microcontroller determines that the insulation condition is deteriorating and performs an adjustment operation. When adjusting the frequency of the modulation signal, the microcontroller writes a new frequency control word to the direct digital frequency synthesizer chip in step S102 via the serial peripheral interface bus, increasing the frequency of the modulation signal from the current 50 kHz to 60 kHz. When adjusting the injected charge of the charge-controlled pulse sequence, the microcontroller controls a digital potentiometer connected before the H-bridge auxiliary power supply +V_HB and -V_HB in step S104 via the I2C bus, increasing the absolute values ​​of the voltages of +V_HB and -V_HB from 100V to 120V. Since the injected charge Q is approximately proportional to the pulse voltage amplitude V (Q∝CV, C is the equivalent capacitance), increasing the voltage amplitude increases the injected charge. When PD_Rate is less than or equal to Th_PD, the microcontroller maintains the current modulation signal frequency and H-bridge power supply voltage.If PD_Rate remains below a lower second preset threshold (e.g., 20 pulses / second) for a period of time, the microcontroller can perform a reduction operation, such as reducing the modulation signal frequency to 45 kHz or reducing the H-bridge power supply voltage to 90V, to optimize energy efficiency.

[0078] Optionally, the specific implementation of "maintaining or reducing the frequency of the modulation signal, and / or maintaining or reducing the injected charge amount of the charge-controlled pulse sequence" is as follows:

[0079] The microcontroller also stores a second preset threshold, Th_low, which is less than the first preset threshold, Th_PD. For example, Th_low can be set to 20 pulses / second. The microcontroller's adjustment logic is as follows:

[0080] 1. Maintenance strategy: When the real-time measured value of the dielectric characteristic parameter (such as PD_Rate) is less than or equal to Th_PD but greater than Th_low, the microcontroller determines that the insulation state is stable and maintains the current modulation signal frequency and H-bridge auxiliary power supply voltage V_HB unchanged.

[0081] 2. Reduction Strategy: When the real-time measured value of the dielectric characteristic parameter (such as PD_Rate) remains below Th_low for a preset stabilization time T_stable (e.g., 5 minutes), the microcontroller determines that the insulation state is excellent and the intervention intensity may be excessive. To optimize system energy efficiency, a reduction operation is executed. Specifically, the microcontroller reduces the output frequency of the direct digital frequency synthesizer chip from its current value (e.g., 50kHz) to a lower frequency (e.g., 45kHz) via the serial peripheral interface bus; simultaneously, it controls the digital potentiometer via the I2C bus to reduce the absolute values ​​of the H-bridge auxiliary power supply voltages +V_HB and -V_HB from their current values ​​(e.g., 100V) to a lower voltage (e.g., 90V). This "reduction" operation, together with the "increase" operation, constitutes a complete, bidirectional closed-loop optimization control, enabling the system to adaptively and dynamically adjust near the optimal intervention point according to the real-time state of the insulating medium.

[0082] This step quantitatively acquires physical parameters characterizing the insulation aging state (partial discharge repetition rate or dielectric loss tangent) through specific sensors and measurement circuits (RF current sensor, bandpass filter, pulse counting circuit, or LCR measurement bridge). Based on specific, programmable threshold comparison logic, the microcontroller dynamically and in a closed loop adjusts the modulation signal frequency and injected pulse voltage amplitude from the previous step. This enables the entire charge cancellation intervention system to adaptively optimize the intervention intensity and strategy according to the real-time state of the insulation medium, ensuring that there is no excessive intervention when the insulation is in good condition and strengthening protection when a deterioration trend appears. Ultimately, this achieves long-term, adaptive, and optimized insulation reliability and lifespan improvement, completing a key upgrade from open-loop intervention to intelligent closed-loop control.

[0083] Optionally, in embodiments of the present invention, the key parameters such as the "preset rate of change threshold," "first preset threshold," and "second preset threshold" can be determined by one or more of the following methods to ensure their scientific validity and effectiveness:

[0084] 1. Theoretical Calculation and Simulation Based on Insulating Material Properties: For the specific insulating medium (such as FR-4) used in the PCB winding, an electric field-charge coupling simulation model under high-frequency square wave voltage is established using finite element analysis software (such as COMSOL Multiphysics) based on its dielectric constant, volume resistivity, trap energy level distribution, and other parameters. By simulating the electric field distortion and space charge accumulation inside the medium under different voltage change rates (dv / dt), the dv / dt value that causes the local electric field strength to approach the intrinsic breakdown field strength of the material (e.g., approximately 15-20 kV / mm for FR-4) at a certain proportion (e.g., 80%) is set as a reference benchmark for the "preset change rate threshold".

[0085] 2. Accelerated Aging Test-Based Calibration: Prepare a batch of PCB winding samples with the same structure as the target product. Under conditions where charge cancellation is not enabled, apply high-frequency, high-voltage stress exceeding rated conditions to the samples for accelerated electrothermal aging testing. Periodically measure the partial discharge initiation voltage, partial discharge repetition rate (PD_Rate), and dielectric loss tangent (tanδ) of the samples offline. Record the inflection point value at which PD_Rate or tanδ begins to rise nonlinearly and sharply before insulation failure (such as breakdown) occurs. Multiply this inflection point value by a safety factor (e.g., 0.7) and set it as the "first preset threshold" (Th_PD or Th_tanδ). The "second preset threshold" (Th_low) can be set to an empirical value much lower than this inflection point, indicating very good insulation condition.

[0086] 3. Reference to Industry Standards and Specifications: The "preset rate of change threshold" can also refer to the design specifications of relevant power electronic equipment or insulation systems. For example, in IEC or national standards for specific voltage levels, the limitation requirements for transient overshoot voltage of switches can indirectly derive the upper limit of the allowable voltage change rate, which can serve as the basis for setting the threshold.

[0087] In practical applications, the above methods can be used in combination. First, the initial threshold is determined through simulation and standards. Then, aging experiments are conducted on the prototype for verification and fine-tuning. Finally, the threshold parameters applicable to a specific product model are determined.

[0088] This embodiment provides a layered insulation and voltage equalization method for PCB windings of high-frequency fast-charging transformers. This method involves setting multiple independent charge injection electrodes, electrically isolated from the main power circuit, in the PCB winding insulation dielectric layer, generating a modulation signal with a frequency different from the main power circuit's operating frequency. By monitoring the port voltage change rate, a charge-controlled pulse sequence synchronized with the main power circuit's switching action is generated in conjunction with the modulation signal and applied to the corresponding electrodes. During voltage abrupt changes, charges that can compensate for spatial charge separation are injected into the insulation dielectric layer. Simultaneously, dielectric characteristic parameters reflecting the state of the insulation dielectric layer are collected, and the amount of injected charge in the modulation signal parameters or charge-controlled pulse sequence is adjusted based on comparisons with preset thresholds. This voltage equalization method effectively solves the problems of local electric field distortion and long-term insulation reliability degradation under high-frequency transients, improves the transient electric field uniformity of the insulation system under high-frequency repetitive pulse stress, suppresses insulation aging, and extends the service life and operational reliability of equipment under harsh operating conditions.

[0089] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only.

[0090] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope.

Claims

1. A method for layered insulation and voltage equalization of PCB windings in a high-frequency fast-charging transformer, characterized in that, The method includes: Multiple independent charge injection electrodes are disposed in the insulating dielectric layer of the PCB winding, and each charge injection electrode is electrically isolated from the main power circuit of the PCB winding. A modulation signal is generated, the frequency of which is different from the operating frequency of the main power circuit; The voltage change rate at the port of the PCB winding is monitored, and a charge control pulse sequence is generated based on the modulation signal and the voltage change rate. The timing of the charge control pulse sequence is synchronized with the switching action of the main power circuit. The charge-controlled pulse sequence is applied to the corresponding charge injection electrode to inject charge into the insulating dielectric layer during the voltage change phase corresponding to the switching action. The polarity of the injected charge can counteract the space charge separation caused by the voltage change in the insulating dielectric layer. Dielectric characteristic parameters reflecting the state of the insulating dielectric layer are collected, and based on the comparison results of the dielectric characteristic parameters with a preset threshold, the parameters of the modulation signal and / or the amount of injected charge of the charge-controlled pulse sequence are adjusted.

2. The method for layered insulation and voltage equalization of PCB windings of a high-frequency fast-charging transformer according to claim 1, characterized in that, The method involves providing multiple independent charge injection electrodes in the insulating dielectric layer of the PCB winding, each charge injection electrode being electrically isolated from the main power circuit of the PCB winding, including: In the insulating dielectric layer, at a predetermined position between adjacent winding layers or in the insulating gap between the winding layer and the magnetic core, a metal foil is etched to form the charge injection electrode; Electrical isolation is achieved by connecting the metal foil to a drive trace independent of the main power circuit through insulating vias.

3. The method for layered insulation and voltage equalization of the PCB windings of a high-frequency fast-charging transformer according to claim 1, characterized in that, The generation of the modulation signal, wherein the frequency of the modulation signal is different from the operating frequency of the main power circuit, includes: A square wave signal is generated using a separate signal generator as the modulation signal; The frequency of the square wave signal is set to 1 / N of the operating frequency of the main power circuit, where N is an integer greater than 2.

4. The method for layered insulation and voltage equalization of the PCB windings of a high-frequency fast-charging transformer according to claim 1, characterized in that, The monitoring of the voltage change rate at the port of the PCB winding includes: The voltage waveform at the PCB winding port is acquired using a high-voltage differential probe; The voltage waveform is input into a differentiating circuit to calculate the voltage change rate.

5. The method for layered insulation and voltage equalization of the PCB windings of a high-frequency fast-charging transformer according to claim 1, characterized in that, The generation of a charge-controlled pulse sequence based on the modulation signal and the voltage change rate, wherein the timing of the charge-controlled pulse sequence is synchronized with the switching action of the main power circuit, includes: When the absolute value of the voltage change rate is detected to exceed a preset change rate threshold, a pulse generation enable signal is triggered. During the period when the pulse generation enable signal is active, the modulation signal is converted into a pulse synchronized with the rising or falling edge of the switching action, forming the charge control pulse sequence.

6. The method for layered insulation and voltage equalization of the PCB windings of a high-frequency fast-charging transformer according to claim 1, characterized in that, The step of applying the charge-controlled pulse sequence to the corresponding charge injection electrode to inject charge into the insulating dielectric layer during the voltage change phase corresponding to the switching action includes: The charge-controlled pulse sequence is received via a high-speed isolation driver; The high-speed isolation driver converts the charge-controlled pulse sequence into a high-voltage isolation pulse and applies it to the corresponding charge injection electrode through the drive trace.

7. The method for layered insulation and voltage equalization of the PCB windings of a high-frequency fast-charging transformer according to claim 1, characterized in that, The polarity of the injected charge can counteract the space charge separation caused by the voltage change in the insulating dielectric layer, including: The polarity of the space charge induced in the insulating dielectric layer is determined based on the polarity of the voltage change. The polarity of the charge modulation pulse sequence is controlled so that the charge injection electrode injects a charge with the opposite polarity to the space charge into the insulating dielectric layer.

8. The method for layered insulation and voltage equalization of the PCB windings of a high-frequency fast-charging transformer according to claim 1, characterized in that, The acquisition of dielectric characteristic parameters reflecting the state of the insulating dielectric layer includes: Partial discharge signals are acquired by an RF current sensor coupled to the PCB winding, and the repetition rate or average amplitude of the partial discharge signals is used as the dielectric characteristic parameter; or, The dielectric loss tangent is measured using an LCR bridge when a test signal is applied to the PCB winding, and the dielectric loss tangent is used as the dielectric characteristic parameter.

9. The method for layered insulation and voltage equalization of the PCB windings of a high-frequency fast-charging transformer according to claim 1, characterized in that, The step of adjusting the parameters of the modulation signal and / or the injected charge amount of the charge-controlled pulse sequence based on the comparison result of the dielectric characteristic parameters and the preset threshold includes: Compare the dielectric characteristic parameters with a first preset threshold; When the dielectric characteristic parameter is greater than the first preset threshold, the frequency of the modulation signal is increased, and / or the amount of injected charge in the charge-controlled pulse sequence is increased; When the dielectric characteristic parameter is less than or equal to the first preset threshold, the frequency of the modulation signal is maintained or decreased, and / or the injected charge of the charge-controlled pulse sequence is maintained or decreased.

10. The method for layered insulation and voltage equalization of the PCB windings of a high-frequency fast-charging transformer according to claim 9, characterized in that, Increasing the injected charge amount of the charge-controlled pulse sequence includes: Increase the voltage amplitude of a single pulse in the charge-controlled pulse sequence.

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