An electrolytic voltage dynamic induction regulation method for hydrogen production by alkaline electrolysis

Abstract

This invention discloses a method for dynamically inducing and controlling the electrolysis voltage in alkaline electrolysis for hydrogen production. This method is implemented through a control circuit and specifically includes: acquiring the input power of the alkaline electrolyzer and comparing it with a set power; if the input power is greater than or equal to the set power, controlling the control circuit to operate in conventional DC electrolysis mode; if the input power is less than the set power, controlling the control circuit to operate in dynamic induced electrolysis mode; in dynamic induced electrolysis mode, based on the input power and the electrochemical state of the alkaline electrolyzer, adaptively controlling the amplitude and frequency of the electrolysis current applied to the alkaline electrolyzer to suppress the corrosion of the nickel electrode by reverse current and extend the service life of the alkaline electrolyzer. This invention can achieve electrolysis voltage control solely by adjusting the electrolysis current without changing the electrode materials or the structure of the alkaline electrolyzer, without any additional lossy materials, and has good economic value and broad application prospects.

Description

Technical Field

[0001] This invention belongs to the field of alkaline electrolysis hydrogen production technology in the new energy sector, specifically relating to a method for dynamic induction and control of electrolysis voltage in alkaline electrolysis hydrogen production. Background Technology

[0002] Energy is a vital material foundation for human survival and development, and low-carbon energy development is crucial to humanity's future. Hydrogen energy, an abundant, green, low-carbon, and widely applicable secondary energy source, is gradually becoming one of the important carriers of global energy transition. With the development of renewable energy sources such as wind and solar power, electrolytic hydrogen production has attracted much attention due to its pollution-free byproducts. Currently, there are several renewable energy hydrogen production schemes, including alkaline water electrolysis, proton exchange membrane water electrolysis, anion exchange membrane water electrolysis, and solid oxide water electrolysis. Alkaline water electrolysis is suitable for large-scale deployment due to its low initial investment cost, high technological maturity, and relatively low operation and maintenance costs.

[0003] However, renewable energy electrolysis for hydrogen production faces many problems. For example, due to the intermittency and volatility of renewable energy, alkaline electrolyzers frequently operate at low power during water electrolysis, sometimes forcing them to shut down. Furthermore, alkaline electrolyzers spontaneously generate reverse current during low-power electrolysis, which corrodes the electrodes, shortens the lifespan of the alkaline electrolyzer, and increases its operation and maintenance costs.

[0004] Therefore, there is an urgent need for a method for dynamic induction and control of the electrolysis voltage in alkaline electrolysis for hydrogen production, in order to solve the above problems. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a method for dynamic induction and control of electrolysis voltage in alkaline electrolysis for hydrogen production. This invention successfully solves the inherent problem of alkaline electrolyzers being unable to adapt to frequent power fluctuations or even forced shutdowns, providing a reliable guarantee for their long-term, stable, and efficient operation in new energy power generation.

[0006] The objective of this invention is achieved through the following technical solution: a method for dynamically inducing and controlling the electrolysis voltage in alkaline electrolysis for hydrogen production, implemented through a control circuit, specifically including:

[0007] Obtain the input power of the alkaline electrolyzer and compare it with the set power;

[0008] If the input power is greater than or equal to the set power, the control and regulation circuit will operate in the traditional DC electrolysis mode.

[0009] If the input power is less than the set power, the control and regulation circuit will operate in dynamic induced electrolysis mode.

[0010] The control circuit includes a DC / DC converter circuit and an electrolysis voltage dynamic induction circuit. The input terminal of the DC / DC converter circuit is connected to a DC power supply, and the output terminal of the DC / DC converter circuit is connected to the input terminal of the electrolysis voltage dynamic induction circuit. The output terminal of the electrolysis voltage dynamic induction circuit is connected to an alkaline electrolytic cell.

[0011] In the dynamic induced electrolysis mode, the amplitude and frequency of the electrolytic current applied to the alkaline electrolytic cell are adaptively controlled according to the input power and the electrochemical state of the alkaline electrolytic cell to suppress the corrosion of the nickel electrode by the reverse current.

[0012] Furthermore, the DC / DC converter circuit is any one of a phase-shifted full-bridge converter, a dual active bridge converter, and a buck circuit.

[0013] Furthermore, the electrolysis voltage dynamic induction circuit includes a first switching transistor, an inductor, a capacitor, a diode, and a second switching transistor. The collector of the first switching transistor is connected to the positive output terminal of the DC / DC converter circuit, and the emitter of the first switching transistor is simultaneously connected to one end of the inductor and the collector of the second switching transistor. The other end of the inductor is simultaneously connected to the positive terminal of the capacitor and the anode of the diode. The cathode of the diode serves as the positive output terminal of the electrolysis voltage dynamic induction circuit and is connected to the positive terminal of the alkaline electrolytic cell. The emitter of the second switching transistor, the negative terminal of the capacitor, and the negative output terminal of the DC / DC converter circuit together serve as the negative output terminal of the electrolysis voltage dynamic induction circuit and are connected to the negative terminal of the alkaline electrolytic cell.

[0014] Furthermore, the conventional DC electrolysis mode includes:

[0015] By controlling the fully controlled switching transistors inside the DC / DC converter circuit, a stable output current is achieved; at the same time, the first switching transistor is kept normally on and the second switching transistor is kept normally off, so that the current flowing through the inductor is continuous and equal to the input current.

[0016] Furthermore, in the dynamic induced electrolysis mode, controlling the amplitude of the electrolysis current specifically includes:

[0017] The maximum value of the current flowing through the inductor is equal to the optimal electrolytic current under the current input power; the optimal electrolytic current is determined according to the following formula:

[0018]

[0019] In the formula, The current is the optimal electrolysis current under the current input power, and D is the ratio of the input power to the rated power of the alkaline electrolyzer at its optimal electrolysis efficiency. Input power is the set power The corresponding electrolytic current.

[0020] Furthermore, in the aforementioned dynamic induced electrolysis mode, controlling the duty cycle of the electrolysis current specifically includes:

[0021] The duty cycle is the ratio of the time during which the voltage applied to the electrodes across the alkaline electrolyzer is higher than the threshold voltage within a single switching cycle. ;

[0022] The threshold voltage is the critical voltage at which the cathode plate in a galvanic cell consisting of bipolar plates and alkaline solution in an alkaline electrolytic cell changes from metallic nickel to nickel hydroxide when the input power is less than the set power.

[0023] The duty cycle Adjustments are made based on the real-time input power, satisfying the following formula:

[0024]

[0025] In the formula, This refers to the real-time input power of the alkaline electrolyzer. This represents the input power of the alkaline electrolyzer at its highest electrolysis efficiency.

[0026] Furthermore, in the dynamic induced electrolysis mode, regulating the frequency of the electrolysis current specifically includes:

[0027] Real-time monitoring of the voltage in individual electrolysis cells of an alkaline electrolyzer. and when the voltage was detected satisfy At that time, according to the duty cycle Adaptive adjustment of electrolytic current frequency ;in This is the critical voltage at which metallic nickel begins to transform into nickel hydroxide;

[0028] Adjusted frequency Satisfy the following formula:

[0029]

[0030] In the formula, This refers to the time it takes for reverse current to be generated when the input power of the alkaline electrolyzer is less than the set power. This is the reaction time constant for when the input power of the alkaline electrolytic cell is less than the set power, at which point metallic nickel begins to transform into nickel hydroxide.

[0031] Furthermore, the duty cycle and the frequency The control is specifically achieved by adaptively adjusting the switching frequencies of the first and second switches through a control signal generator.

[0032] Compared with existing technologies, the beneficial effects of this invention are as follows: The circuit topology and control strategy adopted in this invention do not require changes to electrode materials or modifications to the electrolytic cell structure. Even under fluctuating operating conditions in an alkaline electrolytic cell, it adaptively applies periodic current based on the time-varying law of electrode potential, effectively suppressing the corrosion of metallic nickel by reverse current, thereby significantly extending the service life of the electrolytic cell. Compared with existing sacrificial external protective layer methods, this invention achieves the protective effect solely through adaptive regulation of the electrolytic current, requiring no additional consumable materials or other additional lossy materials. This not only reduces operation and maintenance costs but also possesses higher economic efficiency and promising prospects for widespread application. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the control circuit used to realize the dynamic induction and control method of electrolysis voltage for hydrogen production by alkaline electrolysis;

[0034] Figure 2 This is a schematic diagram illustrating the process of reverse current generation on the internal plates of an alkaline electrolytic cell when it is shut down.

[0035] Figure 3 This is a schematic diagram of typical current waveforms output under traditional DC electrolysis mode and dynamic induced electrolysis mode. Detailed Implementation

[0036] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of apparatuses and methods consistent with some aspects of the invention as detailed in the appended claims.

[0037] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular forms “a,” “the,” and “the” used in this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0038] It should be understood that although the terms first, second, third, etc., may be used in this invention to describe various information, this information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, first information may also be referred to as second information without departing from the scope of this invention, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to a determination."

[0039] The present invention will now be described in detail with reference to the accompanying drawings. Unless otherwise specified, the features of the following embodiments and implementations can be combined with each other.

[0040] The method for dynamic induction and control of electrolysis voltage in alkaline electrolysis hydrogen production of the present invention is implemented through a control circuit, specifically including: obtaining the input power of the alkaline electrolyzer. and compare it with the set power Compare; if input power Greater than or equal to the set power When the input power is low, the control circuit operates in the traditional DC electrolysis mode; if the input power is high... Less than the set power When the current state is reached, the control and regulation circuit operates in dynamic induced electrolysis mode. This control circuit includes a DC / DC converter circuit and an electrolysis voltage dynamic induction circuit. The input of the DC / DC converter circuit is connected to a DC power supply, and its output is connected to the input of the electrolysis voltage dynamic induction circuit. The output of the electrolysis voltage dynamic induction circuit is connected to the alkaline electrolytic cell, such as... Figure 1 As shown. In dynamic induced electrolysis mode, based on the input power Based on the electrochemical state of the alkaline electrolytic cell, the amplitude and frequency of the electrolytic current applied to the alkaline electrolytic cell are adaptively and precisely controlled to suppress the corrosion of the nickel electrode by the reverse current.

[0041] Furthermore, the DC / DC converter circuit can be any one of a phase-shifted full-bridge converter, a dual active bridge converter, and a buck circuit.

[0042] Furthermore, the electrolysis voltage dynamic induction circuit includes a first switch Q1, an inductor L, a capacitor C, a diode D, and a second switch Q2. The collector of the first switch Q1 is connected to the positive output terminal of the DC / DC converter circuit, and the emitter of the first switch Q1 is connected to one end of the inductor L and the collector of the second switch Q2. The other end of the inductor L is connected to the positive terminal of the capacitor C and the anode of the diode D. The cathode of the diode D serves as the positive output terminal of the electrolysis voltage dynamic induction circuit and is connected to the positive terminal of the alkaline electrolytic cell. The emitter of the second switch Q2, the negative terminal of the capacitor C, and the negative output terminal of the DC / DC converter circuit together serve as the negative output terminal of the electrolysis voltage dynamic induction circuit and are connected to the negative terminal of the alkaline electrolytic cell.

[0043] Furthermore, when the input power of the alkaline electrolyzer... Greater than or equal to the set power At this time, the control and regulation circuit operates in the traditional DC electrolysis mode. The traditional DC electrolysis mode includes: adjusting the output power of the DC / DC converter circuit by controlling the fully controlled switching transistors inside the DC / DC converter circuit to ensure a stable output current; simultaneously controlling the first switching transistor Q1 to remain normally on and the second switching transistor Q2 to remain normally off, so that the current flowing through the inductor L... The current is continuous and equal to the input current I, thus providing a stable DC current for efficient electrolysis in the alkaline electrolyzer.

[0044] Furthermore, when the input power of the alkaline electrolyzer... Less than the set power (For example, when photovoltaic power generation decreases in the evening or on cloudy days), the control circuit switches to dynamic induced electrolysis mode. The core of this mode is the generation of a pulsed current. By precisely controlling its amplitude, duty cycle, and frequency, a dynamic balance is established between electrolysis and electrochemical protection. The process of generating reverse current on the internal plates when an alkaline electrolyzer shuts down is as follows: Figure 2 As shown, it is therefore necessary to switch to dynamic induced electrolysis mode to suppress the corrosion of the nickel electrode by reverse current. In dynamic induced electrolysis mode, the control signal generator adjusts the input power... Based on the electrochemical state of the alkaline electrolytic cell (i.e., the change of reverse current over time), the amplitude and frequency of the electrolytic current applied to the alkaline electrolytic cell by the dynamic induction circuit of the electrolytic voltage are adaptively controlled to prevent corrosion of the nickel electrode by the reverse current. The specific control method is as follows:

[0045] (1) Adjusting the amplitude of the electrolytic current: controlling the current flowing through the inductor The maximum value is equal to the current input power. Optimal electrolysis current Among them, the optimal electrolysis current Determined according to the following formula:

[0046]

[0047] In the formula, D is the input power of the alkaline electrolyzer at its optimal electrolysis efficiency. With rated power The ratio, Input power is the set power The corresponding electrolytic current.

[0048] Specifically, when adjusting the amplitude of the electrolysis current, firstly, based on the real-time input power... Calculate the optimal electrolysis current Subsequently, the control signal generator controls the on-time of the first switch Q1 and the second switch Q2, causing the peak current flowing through the inductor L to reach... This ensures that electrolysis is performed at the highest efficiency during pulse conduction.

[0049] (2) Adjusting the duty cycle of the electrolytic current: In order to prevent the voltage rise caused by the galvanic cell effect during the current turn-off period from corroding the electrodes, it is necessary to precisely control the plate voltage. Above the threshold voltage Time. Threshold voltage This is a key parameter, which can be determined through previous experiments. It characterizes the critical potential at which the nickel electrode begins to oxidize under specific electrolyte concentrations and temperatures. It controls the electrolytic current within a switching cycle. So as to increase the voltage applied to the plates at both ends of the alkaline electrolytic cell Above the threshold voltage The ratio of time spent in the entire cycle is called the duty cycle. Threshold voltage For input power Less than the set power Under certain operating conditions, in a galvanic cell consisting of bipolar plates in an alkaline electrolytic cell and alkaline solution, the critical voltage at which the cathode plate transitions from metallic nickel (Ni) to nickel hydroxide (Ni(OH)2) is reached; the duty cycle... Based on real-time input power Adjustments are made to satisfy the following equation:

[0050]

[0051] In the formula, Duty cycle, This is the input power for the alkaline electrolyzer. This represents the input power of the alkaline electrolyzer at its highest electrolysis efficiency. The control signal generator operates based on the real-time input power. Adjusting the duty cycle of the electrolysis current This means that the lower the input power and the smaller the duty cycle, the lower the plate voltage. Above the threshold voltage The shorter the time, the less time is left for the galvanic cell to react, thus inhibiting corrosion.

[0052] (3) Adjusting the frequency of the electrolysis current: such as Figure 2 As shown, an alkaline electrolyzer is a complex electrochemical system whose state changes over time. This can be monitored in real time by monitoring the voltage of individual electrolysis cells. To detect this change. Real-time monitoring of the voltage in individual electrolysis cells within the alkaline electrolyzer. When voltage is detected satisfy When this occurs, it indicates that the nickel electrode is at risk of oxidation. In this case, the reaction can be based on a preset reverse current generation time. and the time constant of nickel oxidation reaction According to the duty cycle Adaptive adjustment of electrolysis current frequency ;in The critical voltage at which metallic Ni begins to transform into Ni(OH)₂ was also determined experimentally. The adjusted frequency... Satisfy the following formula:

[0053]

[0054] In the formula, Input power for alkaline electrolyzer Less than the set power The time of generation of reverse current, Input power for alkaline electrolyzer Less than the set power The reaction time constant at which metallic Ni begins to transform into Ni(OH)2. By increasing the frequency of the electrolysis current and shortening the interval between each cycle, the next electrolysis pulse is ensured to arrive before the metallic nickel undergoes substantial oxidation. This timely switching of the current direction or state dynamically interrupts the oxidation process, prevents corrosion, and achieves highly efficient corrosion protection.

[0055] Furthermore, duty cycle and frequency The regulation is specifically achieved by adaptively adjusting the switching frequencies of the first switch Q1 and the second switch Q2 through a control signal generator, thereby controlling the electrolytic current. The current waveform, exhibiting a triangular wave periodic change, can be flexibly adjusted to supply current to the alkaline electrolyzer. When the plate voltage... Reaching threshold voltage The corresponding reaction time constant is This makes the electrolytic current within one switching cycle... Voltage applied to the electrodes at both ends of the alkaline electrolytic cell Above the threshold voltage The proportion of time in the entire cycle is The frequency is .

[0056] like Figure 3 As shown, the typical current waveforms output in the traditional DC electrolysis mode and the dynamic induced electrolysis mode are shown. In the dynamic induced electrolysis mode, the output electrolysis current exhibits a periodic triangular wave change.

[0057] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for dynamically inducing and regulating electrolysis voltage for hydrogen production by alkaline electrolysis, characterized in that, This is achieved through a control circuit, specifically including: Obtain the input power of the alkaline electrolyzer and compare it with the set power; If the input power is greater than or equal to the set power, the control and regulation circuit will operate in the traditional DC electrolysis mode. If the input power is less than the set power, the control and regulation circuit will operate in dynamic induced electrolysis mode. The control circuit includes a DC / DC converter circuit and an electrolysis voltage dynamic induction circuit. The input terminal of the DC / DC converter circuit is connected to a DC power supply, and the output terminal of the DC / DC converter circuit is connected to the input terminal of the electrolysis voltage dynamic induction circuit. The output terminal of the electrolysis voltage dynamic induction circuit is connected to an alkaline electrolytic cell. The electrolysis voltage dynamic induction circuit includes a first switching transistor, an inductor, a capacitor, a diode, and a second switching transistor. The collector of the first switching transistor is connected to the positive output terminal of the DC / DC converter circuit, and the emitter of the first switching transistor is connected to one end of the inductor and the collector of the second switching transistor. The other end of the inductor is connected to the positive terminal of the capacitor and the anode of the diode. The cathode of the diode serves as the positive output terminal of the electrolysis voltage dynamic induction circuit and is connected to the positive terminal of the alkaline electrolytic cell. The emitter of the second switching transistor, the negative terminal of the capacitor, and the negative output terminal of the DC / DC converter circuit together serve as the negative output terminal of the electrolysis voltage dynamic induction circuit and are connected to the negative terminal of the alkaline electrolytic cell. In the dynamic induced electrolysis mode, the amplitude and frequency of the electrolytic current applied to the alkaline electrolytic cell are adaptively controlled according to the input power and the electrochemical state of the alkaline electrolytic cell to suppress the corrosion of the nickel electrode by the reverse current.

2. The method for dynamic induction and control of electrolysis voltage in alkaline electrolysis for hydrogen production according to claim 1, characterized in that, The DC / DC converter circuit can be any one of a phase-shifted full-bridge converter, a dual active bridge converter, or a buck circuit.

3. The method for dynamic induction and control of electrolysis voltage in alkaline electrolysis for hydrogen production according to claim 1, characterized in that, The traditional DC electrolysis mode includes: By controlling the fully controlled switching transistors inside the DC / DC converter circuit, a stable output current is achieved; at the same time, the first switching transistor is kept normally on and the second switching transistor is kept normally off, so that the current flowing through the inductor is continuous and equal to the input current.

4. The method for dynamic induction and control of electrolysis voltage in alkaline electrolysis for hydrogen production according to claim 1, characterized in that, In the dynamic induced electrolysis mode, the amplitude of the electrolysis current is controlled, specifically including: The maximum value of the current flowing through the inductor is equal to the optimal electrolytic current under the current input power; the optimal electrolytic current is determined according to the following formula: In the formula, The current is the optimal electrolysis current under the current input power, and D is the ratio of the input power to the rated power of the alkaline electrolyzer at its optimal electrolysis efficiency. Input power is the set power The corresponding electrolytic current.

5. The method for dynamic induction and control of electrolysis voltage in alkaline electrolysis hydrogen production according to claim 1, characterized in that, In the dynamic induced electrolysis mode, the duty cycle of the electrolysis current is adjusted, specifically including: The duty cycle is the ratio of the time during which the voltage applied to the electrodes across the alkaline electrolyzer is higher than the threshold voltage within a single switching cycle. ; The threshold voltage is the critical voltage at which the cathode plate in a galvanic cell consisting of bipolar plates and alkaline solution in an alkaline electrolytic cell changes from metallic nickel to nickel hydroxide when the input power is less than the set power. The duty cycle Adjustments are made based on the real-time input power, satisfying the following formula: In the formula, This refers to the real-time input power of the alkaline electrolyzer. This represents the input power of the alkaline electrolyzer at its highest electrolysis efficiency.

6. The method for dynamic induction and control of electrolysis voltage in alkaline electrolysis for hydrogen production according to claim 5, characterized in that, In the dynamic induced electrolysis mode, the frequency of the electrolysis current is adjusted, specifically including: Real-time monitoring of the voltage in individual electrolysis cells of an alkaline electrolyzer. and when the voltage was detected satisfy At that time, according to the duty cycle Adaptive adjustment of electrolytic current frequency ;in This is the critical voltage at which metallic nickel begins to transform into nickel hydroxide; Adjusted frequency Satisfy the following formula: In the formula, This refers to the time it takes for reverse current to be generated when the input power of the alkaline electrolyzer is less than the set power. This is the reaction time constant for when the input power of the alkaline electrolytic cell is less than the set power, at which point metallic nickel begins to transform into nickel hydroxide.

7. The electrolytic voltage dynamic induction regulation method for hydrogen production by electrolysis of lye according to claim 6, wherein The duty cycle and the frequency The control is specifically achieved by adaptively adjusting the switching frequencies of the first and second switches through a control signal generator.

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