Ac-dc hybrid power supply topology and decoupling control method for on-line impedance measurement of electrolytic cell

Abstract

The application provides an AC-DC hybrid power supply topology and decoupling control method for online impedance measurement of an electrolytic cell, relates to the field of power supply equipment, and the AC-DC hybrid power supply topology comprises a main power supply branch, an AC injection branch and a high-frequency decoupling network, wherein the main power supply branch is used for providing DC hydrogen production electric energy for the electrolytic cell, the main power supply branch is connected in parallel with the AC injection branch, the AC injection branch is used for providing disturbance of multiple frequencies, the high-frequency decoupling network is arranged between the main power supply branch and the electrolytic cell, and the high-frequency decoupling network is used for inhibiting high-frequency circulating current, has the advantages of breaking through the bandwidth limitation of a single converter and having the ability to resist parallel shunt interference in a low-frequency band, and improving the accuracy of low-frequency impedance measurement.

Description

Technical Field

[0001] This invention relates to the field of power supply equipment, and in particular to an AC / DC hybrid power supply topology and decoupling control method for online impedance measurement of electrolytic cells. Background Technology

[0002] Electrochemical impedance spectroscopy (EIS) of electrolyzers is the core technology for realizing online sensing of the state of electrolyzers. Its principle is to superimpose multi-frequency sinusoidal perturbation signals on the DC operating point, and extract the impedance characteristics of the whole frequency band by measuring the response relationship between cell voltage and cell current, thereby separating key parameters such as ohmic resistance, charge transfer resistance and mass transfer impedance.

[0003] Existing online EIS measurement solutions suffer from three major bottlenecks in the power supply and signal injection stages, severely restricting measurement accuracy and system reliability. First, the single power converter solution faces a physical conflict between DC power supply and high-frequency bandwidth: high-capacity DC power output requires power devices to operate at low switching frequencies to reduce losses, while a complete EIS signal covers a wide bandwidth of up to 10kHz. These two factors are mutually exclusive in hardware topology design, and direct modulation of the main circuit is limited by the closed-loop control bandwidth, resulting in ineffective injection of high-frequency signals. Second, the AC / DC parallel architecture suffers from severe high-frequency circulating current problems: when an independent DC power supply is connected in parallel with an AC signal source, the traditional DC main circuit exhibits low impedance characteristics at high frequencies, making it easy for injected high-frequency AC disturbances to form beat frequency circulating currents on the DC side. This reduces the signal accuracy injected into the electrolytic cell and may damage the power devices of the DC converter. Third, the control loop actively suppresses low-frequency disturbance signals: In the low-frequency measurement range of 0.1Hz to 10Hz, the inductive reactance of the passive filter inductor decreases significantly, while the conventional DC power supply PI closed-loop controller will treat the low-frequency AC injection signal as a bus disturbance and dynamically suppress it, resulting in severe distortion of the measurement signal in this frequency band, making it impossible to accurately obtain the impedance characteristics that reflect the slow mass transfer and diffusion process of the electrolytic cell.

[0004] Therefore, it is necessary to provide an AC / DC hybrid power supply topology and decoupling control method for online impedance measurement of electrolytic cells, in order to overcome the bandwidth limitation of a single converter and have the ability to resist parallel shunt interference in the low-frequency band, thereby improving the accuracy of low-frequency impedance measurement. Summary of the Invention

[0005] This invention provides a hybrid AC / DC power supply topology for online impedance measurement of an electrolyzer, comprising a main power supply branch, an AC injection branch, and a high-frequency decoupling network. The main power supply branch provides DC hydrogen production power to the electrolyzer. The main power supply branch is connected in parallel with the AC injection branch. The AC injection branch provides disturbances of various frequencies. A high-frequency decoupling network is provided between the main power supply branch and the electrolyzer to suppress high-frequency circulating currents.

[0006] Furthermore, the main power supply branch includes a primary-side full-bridge inverter, a resonant network, a high-frequency isolation transformer, a secondary-side full-bridge rectifier, and a low-pass filter connected in sequence, wherein the low-pass filter is composed of a first filter capacitor and a first filter inductor.

[0007] Furthermore, the AC injection branch includes a full-bridge inverter and an output filter, wherein the output filter is composed of a second filter capacitor and a second filter inductor.

[0008] Furthermore, the high-frequency decoupling network includes a passive blocking inductor, which is connected in series between the first filter capacitor and the electrolytic cell.

[0009] This invention provides a decoupling control method applied to the aforementioned AC / DC hybrid power supply topology for online impedance measurement of an electrolytic cell. The method includes: starting the main power supply branch and operating the electrolytic cell to a set DC electrolysis operating point under closed-loop PI control; employing pure open-loop feedforward control to generate an SPWM modulation wave based on a preset wideband signal sequence and dynamically calibrated fundamental current amplitude; and injecting sinusoidal AC harmonics into the electrolytic cell through the AC injection branch according to the SPWM modulation wave, and achieving active impedance rejection of the main power supply branch through a proportional resonant compensator.

[0010] Furthermore, the electrolyzer is operated to the set DC electrolysis operating point under closed-loop PI control, including: acquiring the current DC bias current of the electrolyzer; calculating the error between the current DC bias current of the electrolyzer and the set reference current, and performing proportional-integral calculation on the error through the PI controller to output the phase shift angle and generate a PWM modulation wave; the main power supply branch provides DC hydrogen production power to the electrolyzer according to the PWM modulation wave until the electrolyzer operates to the set DC electrolysis operating point.

[0011] Further, determining the fundamental current amplitude for dynamic calibration includes: acquiring the current DC bias current of the electrolytic cell; and determining the fundamental current amplitude for dynamic calibration based on a preset ratio and the current DC bias current of the electrolytic cell.

[0012] Furthermore, based on the preset wideband signal sequence and the dynamically calibrated fundamental current amplitude, an SPWM modulation wave is generated, including: for each frequency component of the preset wideband signal sequence, linear superposition is performed in the digital domain according to the dynamically calibrated fundamental current amplitude to synthesize a discrete time-domain reference current waveform, and after per-unit conversion, an SPWM modulation wave is generated through a sinusoidal pulse width modulation generator.

[0013] Furthermore, the active impedance rejection of the main power supply branch is achieved through a proportional resonant compensator, including: setting the resonant gain and resonant bandwidth; determining the resonant center frequency of each target frequency injection point for a preset broadband signal sequence; and the proportional resonant compensator performing active impedance rejection of the main power supply branch based on the resonant gain, resonant bandwidth, and resonant center frequency of the target frequency injection point.

[0014] Furthermore, it also includes: collecting the response voltage and injection current at both ends of the electrolytic cell; performing discrete Fourier transform on the response voltage and injection current, calculating the complex impedance at each frequency point, and generating an online impedance spectrum of the electrolytic cell.

[0015] Compared with existing technologies, the AC / DC hybrid power supply topology and decoupling control method for online impedance measurement of electrolytic cells provided by this invention have at least the following advantages: 1. Compared with conventional direct parallel solutions, this invention achieves complete physical isolation between high and low frequencies, eliminating system circulating currents and hardware losses. Addressing the high-frequency coupling inherent in existing AC / DC multi-source parallel architectures, traditional dual-source direct parallel connections not only generate beat frequency circulating currents flowing to the DC side at high frequencies, but their DC-side PI controllers also dynamically suppress AC disturbances as bus fluctuations at low frequencies (0.1Hz~10Hz), leading to severe distortion of the measurement signal. This invention increases the equivalent impedance of the main circuit at high frequencies on the output side through a series passive blocking inductor, physically cutting off the path of AC high-frequency disturbance signals flowing back to the low-impedance DC side. Simultaneously, the high-frequency π-type filter network constructed on the input side effectively absorbs and suppresses the difference frequency / beat frequency circulating currents generated by the independent switching frequencies of the AC and DC branches. No reactive power circulating currents are generated on the entire hybrid AC / DC side, avoiding high-frequency signal energy loss and ensuring the reliable operation of the strong DC main circuit and its switching devices.

[0016] 2. By introducing a proportional resonant compensator into the main circuit feedback loop, low-frequency decoupling at the software level was achieved. By reshaping the gain characteristics of the main circuit control loop, the equivalent active impedance of the DC main circuit at a specific low-frequency injection point was actively increased. This ensured that the small low-frequency signal injected from the auxiliary circuit could flow into the electrolyzer in full and with high fidelity, avoiding low-frequency signal distortion and thus providing an accurate excitation source for observing the slow, second-level mass transfer and diffusion processes inside the electrolyzer.

[0017] 3. This enables physical and logical separation between the high-capacity steady-state DC output and the wide-band, high-dynamic AC injection. The AC injection branch employs pure open-loop feedforward control, completely eliminating the limitation of the closed-loop system bandwidth on the upper limit of the injection frequency. It also eliminates the phase delay and amplitude attenuation associated with the closed-loop modulation process, enabling stable output of micro-amplitude disturbances over an extremely wide frequency range (0.1Hz-10kHz), thus meeting the wide-band excitation requirements of the multi-timescale dynamic characteristics within the electrolytic cell for measurement. Attached Figure Description

[0018] This specification will be further described by way of exemplary embodiments, which will be described in detail with reference to the accompanying drawings. These embodiments are not limiting; in these embodiments, the same reference numerals denote the same structures, wherein: Figure 1 This is a schematic diagram of an AC / DC hybrid power supply topology for online impedance measurement of an electrolytic cell, as shown in some embodiments of this specification. Figure 2 This is a schematic diagram of a decoupling control method according to some embodiments of this specification; Figure 3 This is a decoupling control block diagram shown according to some embodiments of this specification; Figure 4 This is a schematic diagram of a proportional resonant compensator according to some embodiments shown in this specification; Figure 5 This is a schematic diagram of the output current waveform of an AC / DC hybrid power supply topology for online impedance measurement of an electrolytic cell, as shown in some embodiments of this specification. Detailed Implementation

[0019] To more clearly illustrate the technical solutions of the embodiments in this specification, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are merely some examples or embodiments of this specification. For those skilled in the art, these drawings can be applied to other similar scenarios without creative effort. Unless obvious from the context or otherwise specified, the same reference numerals in the drawings represent the same structures or operations.

[0020] Figure 1 This is a schematic diagram of an AC / DC hybrid power supply topology for online impedance measurement of an electrolytic cell, as shown in some embodiments of this specification. Figure 1 As shown, the AC / DC hybrid power supply topology used for online impedance measurement of an electrolyzer can include a main power supply branch, an AC injection branch, and a high-frequency decoupling network. The main power supply branch is used to provide DC hydrogen production power to the electrolyzer. The main power supply branch is connected in parallel with the AC injection branch. The AC injection branch is used to provide disturbances of various frequencies. A high-frequency decoupling network is set between the main power supply branch and the electrolyzer to suppress high-frequency circulating currents.

[0021] like Figure 1 As shown, the main power supply branch (PSFB) includes primary-side full-bridge inverters connected in sequence (by... , , , Composition), resonant network (composed of) , Composition), high-frequency isolation transformer, secondary full-bridge rectifier (composed of) , , , (Composition) and a low-pass filter, wherein the low-pass filter consists of a first filter capacitor. and the first filter inductor constitute.

[0022] Specifically, the primary-side full-bridge inverter converts DC power into high-frequency square-wave AC power through high-frequency switching. The current then enters a resonant network, utilizing its resonant characteristics to achieve soft switching of the switching transistors, thereby significantly reducing switching losses and improving conversion efficiency. The energy from the resonant network is then transferred to the secondary side via a high-frequency isolation transformer for voltage conversion and electrical isolation. The secondary-side full-bridge rectifier rectifies the high-frequency AC power back to pulsating DC power, and a low-pass filter removes high-frequency ripple, smoothing the output current and ultimately supplying stable DC power to the electrolytic cell.

[0023] The main power supply branch can also be an LLC resonant converter, an interleaved parallel Buck converter, or a bidirectional active full-bridge (DAB) converter, etc.

[0024] like Figure 1 As shown, the AC injection branch (INVT) includes a full-bridge inverter (composed of...) , , , (Composition) and output filter, wherein the output filter consists of a second filter capacitor. Second filter inductor constitute.

[0025] Specifically, the full-bridge inverter receives an SPWM modulation signal from the control system and converts the DC bus voltage into a high-frequency AC voltage by chopping. The filtered, clean AC current is injected into the power supply circuit through the coupling inductor and superimposed on the DC operating current of the electrolytic cell.

[0026] The AC injection branch can also be a single-phase half-bridge inverter, a multi-level inverter, or a high-frequency linear power amplifier circuit, etc.

[0027] like Figure 1 As shown, the high-frequency decoupling network includes a passive blocking inductor. The passive blocking inductor is connected in series with the first filter capacitor. Between the electrolytic cell and the main power supply branch and the AC injection branch, directly connecting them in parallel would cause high-frequency disturbance signals to flow into the low-impedance DC-side circuit. Therefore, a passive blocking inductor is used. It is used to withstand transient output voltage differences and improve the equivalent impedance of the main power supply branch in the 10Hz~10kHz high frequency range. The hardware short-circuit path for cutting off high-frequency signals has the following high-frequency equivalent impedance model:

[0028] in, For the Laplace operator, This is the first filter inductor in the output low-pass filter of the main power supply branch. The first filter capacitor in the output low-pass filter of the main power supply branch. The first filter capacitor The equivalent series resistance or the equivalent damping resistance of the output filter branch.

[0029] Figure 5 This is a schematic diagram of the output current waveform of an AC / DC hybrid power supply topology for online impedance measurement of an electrolytic cell, as shown in some embodiments of this specification. Figure 5 As shown, the output current of the AC / DC hybrid power supply topology used for online impedance measurement of the electrolytic cell is expressed as:

[0030] in, For output current, This is the current DC bias current of the electrolytic cell. AC harmonic current injected into the AC injection branch.

[0031] like Figure 1 As shown, a high-frequency capacitor is used on the input power supply side. , With inductance ( , ) series configuration A filter structure is used to absorb and suppress the input-side beat frequency circulating current caused by the inconsistency between the switching frequencies of the main power supply branch and the AC injection branch.

[0032] In addition to using a passive blocking inductor connected in series between the main circuit and the electrolytic cell node, output-side blocking can also employ an LC parallel resonant trap. By connecting the inductor and capacitor in parallel, and designing their resonant frequency near the center frequency of the high-frequency band injected by the auxiliary circuit, it can also exhibit extremely high inductive reactance in a specific high-frequency band, cutting off high-frequency circulating currents. Input-side filtering scheme: In addition to using a π-type LC filter, a network based on a high-frequency common-mode / differential-mode choke combined with a decoupling capacitor can be used on the input side to achieve the equivalent purpose of suppressing the beat frequency interference of the two-branch switches.

[0033] It is worth noting that the main power supply branch, AC injection branch, and high-frequency decoupling network are not simply connected in parallel, but rather a collaborative topology architecture built around the three requirements of "strong DC power supply, wideband small signal injection, and AC / DC branch decoupling" in the online impedance measurement of the electrolyzer.

[0034] Its optimization potential and innovation differences are mainly reflected in the following aspects: First, the main power supply branch's function is not limited to a specific fixed DC / DC converter structure; its core role is to provide a stable, high-power DC electrolysis operating point for the electrolyzer. This branch can utilize PSFB, LLC resonant converters, DAB converters, or other equivalent DC power supply topologies, depending on power level, isolation requirements, voltage conversion ratio, and efficiency requirements. Unlike traditional schemes that directly utilize the main power converter to superimpose disturbance signals, the AC / DC hybrid power supply topology used for online impedance measurement in electrolyzers separates the functions of "high-power DC power supply" and "wideband impedance measurement excitation," allowing the main power supply branch to primarily undertake the task of steady-state hydrogen production energy transmission. This avoids the problem of the main power converter being limited by control bandwidth, switching frequency, and power level, making it difficult to achieve wideband disturbance injection. This functional separation is not simply adding a power supply, but rather a topology division addressing the inconsistency between the high-power DC and small-signal AC bandwidth requirements in online EIS measurements of electrolyzers.

[0035] Secondly, the AC injection branch is not a typical auxiliary power supply or a simple parallel signal source, but rather an independent broadband disturbance injection unit for impedance measurement. This branch can employ a single-phase full-bridge inverter, a half-bridge inverter, a multi-level inverter, a linear power amplifier circuit, or other topologies capable of generating controllable small AC signals. Its optimization focuses on selecting different injection topologies and filtering parameters based on the electrolyzer impedance measurement frequency band, the amplitude of the injected signal, the output ripple accuracy, and the power capacity. Because the AC injection branch uses independent modulation and open-loop feedforward injection, its output frequency is not limited by the main power supply closed-loop bandwidth, enabling it to cover the broadband impedance measurement range corresponding to low-frequency mass transfer processes and mid-to-high-frequency charge transfer and bubble evolution processes. Therefore, the function of this branch is not to provide additional power to the electrolyzer, but rather to provide controllable, repeatable, and analyzable AC excitation for impedance identification under DC hydrogen production conditions.

[0036] Secondly, the high-frequency decoupling network is a key structure for solving the problems of high-frequency circulating current and signal shunting between AC and DC parallel branches. Since the main power supply branch typically exhibits a low-impedance path in the high-frequency band, if the AC injection branch is directly connected in parallel, the injected disturbance signal can easily flow back to the DC main branch, causing attenuation of the signal amplitude actually entering the electrolytic cell and potentially leading to additional power device losses. This solution improves the equivalent impedance of the main power supply branch in the target frequency band by setting a passive blocking inductor, LC wave-blocking network, common-mode / differential-mode decoupling network, or other equivalent high-frequency isolation structures between the main power supply branch and the electrolytic cell. This allows AC disturbances to be preferentially injected into the electrolytic cell body, suppressing high-frequency circulating current between branches at the hardware level. The effect of this decoupling network is to improve the injection path selectivity of AC disturbances, increase the fidelity of the disturbance signal at the electrolytic cell end, and reduce the impact of AC injection on the control stability and device losses of the main power supply branch.

[0037] Furthermore, the AC / DC hybrid power supply topology used for online impedance measurement of the electrolytic cell is optimized by incorporating active decoupling at the control level. For the low-frequency measurement range of 0.1Hz to 10Hz, passive inductors alone cannot provide sufficiently high impedance isolation. Therefore, a proportional resonant compensator, a repetitive controller, or multiple generalized integrators can be introduced into the feedback control loop of the main power supply branch to increase the equivalent output impedance of the main power supply branch at the target injection frequency. This forms a frequency-division decoupling mechanism where "high-frequency bands rely on passive blocking networks, and low-frequency bands rely on active impedance reshaping," ensuring that disturbance signals from different frequency bands can act on the electrolytic cell with high fidelity, rather than being absorbed or suppressed by the main power supply branch. This decoupling concept embodies the synergistic optimization of hardware networks and control strategies, differing from conventional methods that rely solely on a single filter or control loop for isolation.

[0038] Therefore, the innovation of the AC / DC hybrid power supply topology for online impedance measurement of electrolyzers lies in proposing an AC / DC hybrid power supply architecture for online impedance measurement of electrolyzers: the main power supply branch is responsible for stabilizing DC hydrogen production, the AC injection branch is responsible for wideband small-signal excitation, the high-frequency decoupling network is responsible for suppressing branch circulating current, and the active impedance control is responsible for compensating for insufficient low-frequency decoupling. This architecture can achieve wideband impedance measurement under normal DC operation of the electrolyzer, which is different from traditional electrochemical workstation offline frequency sweep, single converter injection, and simple parallel connection of AC / DC signal sources.

[0039] Figure 2 This is a schematic diagram of a decoupling control method according to some embodiments of this specification. The decoupling control method is applied to the above-described AC / DC hybrid power supply topology for online impedance measurement of an electrolytic cell. Due to the passive blocking inductor of the AC / DC hybrid power supply topology for online impedance measurement of an electrolytic cell... The inductive reactance attenuates significantly in the low-frequency range of 0.1Hz-10Hz. Therefore, in this range, decoupling control methods are needed to ensure decoupling capability, such as... Figure 2 As shown, the decoupling control method may include the following steps: Start the main power supply branch and run the electrolytic cell to the set DC electrolysis operating point under closed-loop PI control; Pure open-loop feedforward control is adopted to generate an SPWM modulation wave based on a preset wideband signal sequence and a dynamically calibrated fundamental current amplitude. The AC injection branch injects sinusoidal AC harmonics into the electrolytic cell according to the SPWM modulation wave, and the active impedance of the main power supply branch is resisted by the proportional resonant compensator.

[0040] Figure 3 The decoupling control block diagram shown in some embodiments of this specification is as follows: Figure 3 As shown, in some embodiments, operating the electrolyzer to a set DC electrolysis operating point under closed-loop PI control includes: Collect the current DC bias current of the electrolytic cell ; Calculate the current DC bias current of the electrolyzer. With the set reference current The error is calculated and the PI controller performs proportional-integral calculations on the error to output the phase shift angle. Generates a PWM modulated wave; The main power supply branch provides DC hydrogen production power to the electrolyzer according to the PWM modulation wave until the electrolyzer operates at the set DC electrolysis operating point.

[0041] Specifically, the set DC electrolysis operating point refers to a set of target operating parameters that are pre-set according to the process requirements of hydrogen electrolysis, which enable the electrolyzer to stably and efficiently produce hydrogen through DC electrolysis. These parameters include DC bias voltage and DC bias current.

[0042] Set reference current This is the DC current reference setpoint used to set the steady-state DC operating point of the electrolytic cell. For example, for an electrolytic cell test platform with a maximum rated current of 5A, it is set to 5A when simulating high-power operation and 3A when simulating low-power stabilization operation.

[0043] The preset wideband signal sequence can be a set of multiple sinusoidal frequency points covering a wide frequency range, for example, [0.1,0.2,1,3,10,34,109,350,1124,3605].

[0044] The fundamental current amplitude is the fundamental current amplitude of a single-frequency harmonic component in a broadband AC disturbance signal.

[0045] In some embodiments, determining the dynamically calibrated fundamental current amplitude includes: Collect the current DC bias current of the electrolytic cell; The amplitude of the fundamental current for dynamic calibration is determined based on the preset ratio and the current DC bias current of the electrolytic cell. .

[0046] Specifically, the preset ratio can be 5% to 10%. For example, when the electrolyzer is operating under a 5A steady-state DC condition, It can be set to 0.4A, which is 8% of the current DC bias current of the electrolyzer. Under fluctuating operating conditions driven by renewable energy sources such as wind and solar power, the current DC bias current of the electrolyzer... Due to its time-varying characteristics, this mechanism ensures that the electrolyzer obtains AC excitation that satisfies linear constraints and has the optimal signal-to-noise ratio within the full power tracking range.

[0047] In some embodiments, an SPWM modulation wave is generated based on a preset wideband signal sequence and a dynamically calibrated fundamental current amplitude, including: For each frequency component of the preset wideband signal sequence, linear superposition is performed in the digital domain according to the dynamically calibrated fundamental current amplitude to synthesize a discrete time-domain reference current waveform. After per-unit conversion, an SPWM modulation wave is generated through a sinusoidal pulse width modulation generator.

[0048] Specifically, the given wideband frequency array and corresponding optimized phase array are first read. Based on the dynamically calibrated fundamental current amplitude, linear superposition is performed in the digital domain to synthesize a discrete time-domain reference current waveform. Since each harmonic is completely reconstructed within the observation window, the DC integral mean of the synthesized signal is strictly kept to zero. After the generated time-domain reference waveform is normalized, it is sent to a sinusoidal pulse width modulation (SPWM) generator. This modulation wave is logically intersected in real time with a set high-frequency fixed triangular carrier wave with a switching frequency of 100kHz. The comparator calculates the instantaneous duty cycle based on the intersection point position and width of the reference wave and the triangular carrier wave, generating a series of discrete complementary pulse sequence PWM waves. After dead-time injection, this pulse sequence is directly sent to drive the power switching devices of the bridge arm of the full-bridge inverter in the AC injection branch (INVT) to turn on and off, chopping the DC bus voltage and smoothing it through a filter inductor, converting it into the actual wideband AC disturbance current applied to the electrolytic cell body.

[0049] If only a conventional PI controller is used, the main power supply branch will treat the low-frequency AC current injected by the AC injection branch as a load disturbance and dynamically suppress it, resulting in low-frequency measurement distortion. Therefore, a proportional resonant compensator is needed to achieve active impedance rejection of the main power supply branch and reshape the control loop gain.

[0050] Figure 4This is a schematic diagram of a proportional resonant compensator based on some embodiments shown in this specification, such as... Figure 4 As shown, in some embodiments, active impedance rejection of the main power supply branch is achieved through a proportional resonant compensator, including: Set the resonant gain and resonant bandwidth; For each target frequency injection point (e.g., 0.1Hz, 0.2Hz, etc.) of a preset broadband signal sequence, determine the resonant center frequency of the target frequency injection point; The proportional resonant compensator provides active impedance protection for the main power supply branch based on the resonant gain, resonant bandwidth, and the resonant center frequency of the target frequency injection point.

[0051] Specifically, for the injection points of 0.1Hz and 0.2Hz, the resonant center frequencies are set as follows: and .

[0052] Resonant gain This represents the peak value of the equivalent output impedance at the injection point at that frequency. The principle for choosing this value is to take as large as possible while ensuring the stability of the phase margin of the control system, usually between 500 and 1000, in order to maximize the blocking effect on AC disturbance signals. For example, a value of 800 can be used.

[0053] The resonant bandwidth refers to the range of operation, providing an extremely narrow frequency selection range. Setting a small bandwidth ensures that the proportional resonant compensator provides high impedance within an extremely narrow frequency band of 0.1Hz and 0.2Hz.

[0054] Transfer function of proportional resonant compensator for:

[0055] in, For resonant gain, To control bandwidth parameters, The low-frequency angular frequency of the signal injected into the target.

[0056] The total closed-loop equivalent output impedance is corrected to:

[0057] in, The transfer function of the closed-loop control of the main power supply branch. The transfer function of the controlled object in the inner current loop formed by the filter inductor and the equivalent load of the electrolytic cell in the AC injection branch. The feedback coefficient of the current sampling circuit is denoted as . This is the equivalent gain of the PWM modulation stage.

[0058] This allows the main power supply branch to exhibit high impedance characteristics in the low-frequency band, completely resisting low-frequency coupling interference caused by AC signals from parallel branches.

[0059] In some embodiments, the proportional resonant compensator can be replaced by a repetitive controller or a multiple generalized integrator.

[0060] In some embodiments, the decoupling control method may further include: The response voltage and injected current at both ends of the electrolytic cell are collected; Discrete Fourier transform is performed on the response voltage and injection current to calculate the complex impedance at each frequency point, generating an online impedance spectrum of the electrolytic cell.

[0061] Specifically, since an electrolyzer is essentially a nonlinear, time-varying electrochemical system, it contains multiple physical mechanisms such as ohmic resistance, double-layer capacitance, charge transfer resistance, and mass transfer processes. These mechanisms exhibit different behaviors at different frequencies, thus requiring broadband excitation to probe the impedance characteristics of each frequency band. The acquired response voltage and injection current are time-domain signals. To convert them to the frequency domain for analysis, a Discrete Fourier Transform is performed on these two signals. Specifically, at each preset frequency point, the amplitude and phase of the fundamental components of the response voltage and injection current at that frequency are extracted to obtain complex voltage and current phasors. Then, according to the complex form of Ohm's law, the complex impedance of the electrolyzer at that frequency point is calculated. This complex impedance includes a real part (resistive component) and an imaginary part (reactant component), reflecting the energy loss and energy storage characteristics of the electrolyzer at that frequency, respectively. After performing the above calculations on all frequency points in the preset broadband signal sequence, multiple sets of complex impedance data can be obtained. These data are then plotted on a complex plane or Bode plot in ascending order of frequency to generate an online impedance spectrum of the electrolyzer. This impedance spectrum can intuitively and completely display the impedance distribution characteristics of the electrolyzer across the entire frequency band from 0.1Hz to 3605Hz. The impedance variation trends in different frequency ranges correspond to different electrochemical processes; for example, the low-frequency band mainly reflects the impedance of the mass transfer process, the mid-frequency band mainly reflects the impedance of the charge transfer process, and the high-frequency band mainly reflects the influence of parasitic parameters such as ohmic resistance and parasitic inductance.

[0062] Traditional electrochemical workstations are limited by space constraints and injection power limitations. Single-frequency point sweeping takes several minutes to complete a single broadband scan. Under strong DC hydrogen production conditions, the bubble evolution state within the electrolyzer changes during the slow low-frequency measurement process, disrupting the steady-state prerequisites for EIS testing. Furthermore, these instruments have low output power, making them unsuitable for direct application in high-current industrial scenarios. The topology in this invention inherently possesses high-power, strong DC bias output capability. Combined with open-loop multi-sine superposition injection capability, it can simultaneously extract low-frequency signals reflecting slow mass transfer at the second level and high-frequency signals reflecting rapid bubble evolution at the millisecond level within a short time, making it suitable for broadband online impedance observation of electrochemical processes at different time scales in the electrolyzer.

[0063] Finally, it should be understood that the embodiments described in this specification are merely illustrative of the principles of the embodiments described herein. Other variations may also fall within the scope of this specification. Therefore, alternative configurations of the embodiments described herein are intended to be illustrative rather than limiting, and should be considered consistent with the teachings of this specification. Accordingly, the embodiments described herein are not limited to those explicitly introduced and described herein.

Claims

1. A hybrid AC / DC power supply topology for online impedance measurement of electrolytic cells, characterized in that, It includes a main power supply branch, an AC injection branch, and a high-frequency decoupling network. The main power supply branch is used to provide DC hydrogen production power to the electrolyzer. The main power supply branch is connected in parallel with the AC injection branch. The AC injection branch is used to provide disturbances of multiple frequencies. A high-frequency decoupling network is set between the main power supply branch and the electrolyzer. The high-frequency decoupling network is used to suppress high-frequency circulating currents.

2. The AC / DC hybrid power supply topology for online impedance measurement of electrolytic cells according to claim 1, characterized in that, The main power supply branch includes a primary-side full-bridge inverter, a resonant network, a high-frequency isolation transformer, a secondary-side full-bridge rectifier, and a low-pass filter connected in sequence. The low-pass filter is composed of a first filter capacitor and a first filter inductor.

3. The AC / DC hybrid power supply topology for online impedance measurement of electrolytic cells according to claim 2, characterized in that, The AC injection branch includes a full-bridge inverter and an output filter, wherein the output filter is composed of a second filter capacitor and a second filter inductor.

4. The AC / DC hybrid power supply topology for online impedance measurement of electrolytic cells according to claim 2, characterized in that, The high-frequency decoupling network includes a passive blocking inductor, which is connected in series between the first filter capacitor and the electrolytic cell.

5. A decoupling control method, characterized in that, The AC / DC hybrid power supply topology for online impedance measurement of an electrolytic cell, as described in any one of claims 1-4, comprises: Start the main power supply branch and run the electrolytic cell to the set DC electrolysis operating point under closed-loop PI control; Pure open-loop feedforward control is adopted to generate an SPWM modulation wave based on a preset wideband signal sequence and a dynamically calibrated fundamental current amplitude. The AC injection branch injects sinusoidal AC harmonics into the electrolytic cell according to the SPWM modulation wave, and the active impedance of the main power supply branch is resisted by the proportional resonant compensator.

6. The decoupling control method according to claim 5, characterized in that, Operating the electrolytic cell to the set DC electrolysis operating point under closed-loop PI control includes: Collect the current DC bias current of the electrolytic cell; The error between the current DC bias current of the electrolytic cell and the set reference current is calculated, and the error is calculated by proportional-integral operation through a PI controller to output the phase shift angle and generate a PWM modulation wave. The main power supply branch provides DC hydrogen production power to the electrolyzer according to the PWM modulation wave until the electrolyzer operates at the set DC electrolysis operating point.

7. The decoupling control method according to claim 5, characterized in that, Determining the fundamental current amplitude for dynamic calibration includes: Collect the current DC bias current of the electrolytic cell; The fundamental current amplitude is determined dynamically based on the preset ratio and the current DC bias current of the electrolytic cell.

8. The decoupling control method according to claim 5, characterized in that, Based on a preset wideband signal sequence and a dynamically calibrated fundamental current amplitude, an SPWM modulation wave is generated, including: For each frequency component of the preset wideband signal sequence, linear superposition is performed in the digital domain according to the dynamically calibrated fundamental current amplitude to synthesize a discrete time-domain reference current waveform. After per-unit conversion, an SPWM modulation wave is generated through a sinusoidal pulse width modulation generator.

9. The decoupling control method according to claim 6, characterized in that, Active impedance rejection of the main power supply branch is achieved through a proportional resonant compensator, including: Set the resonant gain and resonant bandwidth; For each target frequency injection point of the preset wideband signal sequence, determine the resonant center frequency of the target frequency injection point; The proportional resonant compensator provides active impedance protection for the main power supply branch based on the resonant gain, resonant bandwidth, and the resonant center frequency of the target frequency injection point.

10. The decoupling control method according to any one of claims 1-9, characterized in that, Also includes: The response voltage and injected current at both ends of the electrolytic cell are collected; Discrete Fourier transform is performed on the response voltage and injection current to calculate the complex impedance at each frequency point, generating an online impedance spectrum of the electrolytic cell.

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