Multi-element isomerization hydrogen production power supply and control method

Abstract

The present specification relates to the technical field of power electronics, and particularly relates to a multi-element heterogeneous hydrogen production power supply and a control method. The power supply comprises a main branch and an auxiliary branch. The main branch comprises a first rectifier circuit and a Buck converter. An input end of the first rectifier circuit is connected with a first output winding of a transformer, an output end of the first rectifier circuit is connected with an input end of the Buck converter, and an output end of the Buck converter is connected with a first end of a DC bus. The main branch is used for providing steady-state power. The first rectifier circuit is an uncontrolled rectifier circuit. The auxiliary branch comprises a second rectifier circuit and a full-bridge circuit. An input end of the second rectifier circuit is connected with a second output winding of the transformer, an output end of the second rectifier circuit is connected with an input end of the full-bridge circuit, and an output end of the full-bridge circuit is connected with the first end of the DC bus. The auxiliary branch is used for transmitting fluctuating power or AC excitation. The embodiments of the present specification can balance between steady-state high efficiency and dynamic fast response.

Description

Technical Field

[0001] This specification relates to the field of power electronics technology, and in particular to a multi-element heterogeneous hydrogen production power source and control method. Background Technology

[0002] With the development of new energy technologies, power supply systems, as a key component of energy conversion, are playing an increasingly important role in the field of power electronics. Especially in high-power applications such as hydrogen production systems, higher demands are placed on the efficiency, reliability, and control flexibility of power supply systems.

[0003] In related technologies, power supply system implementation schemes include insulated-gate bipolar transistor (IGBT) schemes and diode schemes. In the IGBT scheme, a PWM (Pulse Width Modulation) rectifier circuit composed of IGBTs is used. However, the high conduction losses of IGBTs result in low energy conversion efficiency and high cost for the power supply system. In the diode scheme, a diode-based first rectifier circuit is used. However, the output voltage of the diode scheme is uncontrollable, leading to poor dynamic response of the multi-element heterogeneous hydrogen production power supply.

[0004] How to strike a balance between steady-state high efficiency and dynamic rapid response has become a pressing technical problem that needs to be solved. Summary of the Invention

[0005] This specification provides an embodiment of a multi-component heterogeneous hydrogen production power source and control method to achieve a balance between steady-state high efficiency and dynamic fast response.

[0006] This specification provides an embodiment of a multi-element heterogeneous hydrogen production power source, which includes a main branch and an auxiliary branch. The main branch includes a first rectifier circuit and a Buck converter. The input terminal of the first rectifier circuit is connected to the first output winding of the transformer, and the output terminal of the first rectifier circuit is connected to the input terminal of the Buck converter. The output terminal of the Buck converter is connected to the first end of the DC bus. The main branch is used to provide steady-state power to the DC bus. The first rectifier circuit is an uncontrolled rectifier circuit. The auxiliary branch includes a second rectifier circuit and a full-bridge circuit. The input terminal of the second rectifier circuit is connected to the second output winding of the transformer, and the output terminal of the second rectifier circuit is connected to the input terminal of the full-bridge circuit. The output terminal of the full-bridge circuit is connected to the first terminal of the DC bus. The auxiliary branch is used to transmit fluctuating power or AC excitation. The second terminal of the DC bus is connected to the load, which is a hydrogen electrolyzer.

[0007] In some embodiments, the input winding of the transformer is connected to the power grid; the full-bridge circuit is an IGBT full-bridge circuit.

[0008] In some embodiments, the transformer is a phase-shifting transformer; the main branch includes a plurality of first rectifier circuits, the input terminals of the plurality of first rectifier circuits are connected to a plurality of first output windings of the phase-shifting transformer, and the output terminals of the plurality of first rectifier circuits are connected to the input terminals of the Buck converter.

[0009] In some embodiments, the main branch includes a plurality of Buck converters, the output of the first rectifier circuit is connected to the input of the plurality of Buck converters, and the output of the plurality of Buck converters is connected to the first end of the DC bus.

[0010] This specification also provides a control method for a multi-component heterogeneous hydrogen production power source; the control method includes: Obtain the load electrical signal of the load; The target operating mode of the multi-component heterogeneous hydrogen production power source is determined based on the load electrical signal. The Buck converter and the full-bridge circuit are controlled according to the target operating mode.

[0011] In some embodiments, determining the operating mode of the multi-component heterogeneous hydrogen production power source includes: The target condition is selected from the set of conditions based on the load electrical signal. The condition set includes multiple conditions, and the conditions in the condition set correspond to the working modes of the multi-component heterogeneous hydrogen production power source. The target working mode is the working mode corresponding to the target conditions.

[0012] In some embodiments, the target operating mode is a steady-state mode; The control of the Buck converter and the full-bridge circuit includes: The first output voltage of the Buck converter is kept constant. Control the switching transistors in the full-bridge circuit to turn off.

[0013] In some embodiments, the load electrical signal includes load voltage and load current; Determining the target operating mode of the multi-element heterogeneous hydrogen production power source includes: The voltage change index is determined based on the load voltage, and the current change index is determined based on the load current. When the voltage change index is less than or equal to the first threshold and the current change index is less than or equal to the second threshold, the target operating mode of the multi-element heterogeneous hydrogen production power source is determined to be the steady-state mode.

[0014] In some embodiments, the method further includes: Obtain the first output current of the Buck converter and the second output current of the full-bridge circuit; The control of the Buck converter and the full-bridge circuit includes: Calculate the bus reference current of the DC bus based on the load electrical signal and the preset reference voltage; According to the power allocation factor, the bus reference current is allocated to the main branch and the auxiliary branch to obtain the first branch reference current of the main branch and the second branch reference current of the auxiliary branch. Control the Buck converter so that its first output current reaches the first branch reference current; control the full-bridge circuit so that its second output current reaches the second branch reference current.

[0015] In some embodiments, the target operating mode is a dynamic adjustment mode, the power allocation coefficient is a preset power allocation coefficient, and the load electrical signal includes load voltage and load current. Determining the target operating mode of the multi-element heterogeneous hydrogen production power source includes: The voltage change index is determined based on the load voltage, and the current change index is determined based on the load current. The target operating mode of the multi-element heterogeneous hydrogen production power source is determined to be the dynamic adjustment mode when at least one of the following conditions is met: the voltage change index is greater than or equal to the third threshold, and the current change index is greater than or equal to the fourth threshold.

[0016] In some embodiments, the target operating mode is a hybrid modulation mode, the power allocation coefficient is obtained by querying the power allocation coefficient set based on the load voltage, or by calculating based on the load voltage; the load electrical signal includes the load voltage and the load current; Determining the target operating mode of the multi-element heterogeneous hydrogen production power source includes: The voltage change index is determined based on the load voltage, and the current change index is determined based on the load current. The target operating mode of the multi-element heterogeneous hydrogen production power source is determined to be a hybrid modulation mode when at least one of the following conditions is met: the voltage change index is greater than a first threshold and less than a third threshold, and the current change index is greater than a second threshold and less than a fourth threshold.

[0017] In some embodiments, the target operating mode is a fault mode; The control of the Buck converter and the full-bridge circuit includes: Control the switching transistors in the Buck converter to turn off; Control the switching transistors in the full-bridge circuit to turn off.

[0018] In some embodiments, the load electrical signal includes load voltage and load current; determining the target operating mode of the multi-element heterogeneous hydrogen production power source includes: The target operating mode of the multi-element heterogeneous hydrogen production power source is determined to be a fault mode when at least one of the following conditions is met: the load voltage is less than or equal to the voltage threshold, or the load current is greater than or equal to the current threshold.

[0019] In some embodiments, the target operating mode is an electrical excitation superposition mode; The control of the Buck converter and the full-bridge circuit includes: Determine the base voltage and excitation voltage of the load; Control the Buck converter so that the first output voltage of the Buck converter reaches the base voltage; The full-bridge circuit is controlled so that the second output voltage of the full-bridge circuit reaches the excitation voltage.

[0020] In some embodiments, the load is a hydrogen electrolyzer, and the load electrical signal includes load voltage and load current; determining the target operating mode of the multi-element heterogeneous hydrogen production power source includes: The voltage change index is determined based on the load voltage, and the current change index is determined based on the load current. The target operating mode of the multi-element heterogeneous hydrogen production power source is determined to be the electrically excited superposition mode when at least one of the following conditions is met: the voltage change index is greater than or equal to the third threshold, the voltage change index is greater than the first threshold and less than the third threshold, the current change index is greater than or equal to the fourth threshold, and the current change index is greater than the second threshold and less than the fourth threshold.

[0021] This specification also provides a controller, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the above-described control method.

[0022] This specification also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described control method.

[0023] This specification also provides a computer program product, which includes a computer program that, when executed by a processor, implements the above-described control method.

[0024] The technical solution of this specification's embodiment of the multi-element heterogeneous hydrogen production power supply includes a main branch and an auxiliary branch. The main branch includes a first rectifier circuit and a Buck converter. The input terminal of the first rectifier circuit is connected to the first output winding of a transformer, and the output terminal of the first rectifier circuit is connected to the input terminal of the Buck converter. The output terminal of the Buck converter is connected to the first terminal of a DC bus. The main branch is used to provide steady-state power to the DC bus. The first rectifier circuit is an uncontrolled rectifier circuit. The auxiliary branch includes a second rectifier circuit and a full-bridge circuit. The input terminal of the second rectifier circuit is connected to the second output winding of the transformer, and the output terminal of the second rectifier circuit is connected to the input terminal of the full-bridge circuit. The output terminal of the full-bridge circuit is connected to the first terminal of the DC bus. The auxiliary branch is used to transmit fluctuating power or AC excitation. The second terminal of the DC bus is connected to a load. Therefore, the multi-element heterogeneous hydrogen production power supply of this specification's embodiment, including the main branch and auxiliary branch, forms a multi-element heterogeneous hybrid topology. In the aforementioned multi-element heterogeneous hybrid topology, the main branch, based on an uncontrolled rectifier circuit and a Buck converter, handles the primary power transmission, thereby reducing conduction losses and cost while improving energy conversion efficiency. The auxiliary branch, based on a second rectifier circuit and a full-bridge circuit, transmits fluctuating power or AC excitation to achieve precise control and improve dynamic response. Therefore, the embodiments in this specification achieve a balance between steady-state high efficiency and dynamic fast response. Furthermore, the main and auxiliary branches are connected in parallel to the same DC bus, forming a common bus topology. The common bus topology eliminates the need for isolation inductors or additional series converter stages, reducing size and weight while increasing power density. Moreover, the common bus topology facilitates rational power allocation, improving the integration and reliability of the multi-element heterogeneous hydrogen production power supply. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments or prior art of this specification, the drawings used in the description of the embodiments or prior art will be briefly introduced below. The drawings described below are only some embodiments recorded in this specification. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the structure of a multi-element heterogeneous hydrogen production power source in the embodiments of this specification; Figure 2 This is a schematic diagram of a full-bridge circuit as described in one of the embodiments of this specification; Figure 3 This is a flowchart illustrating the control method in the embodiments of this specification.

[0027] The following are some of the reference numerals in the accompanying drawings of the embodiments of this specification: 1. Transformer; 11. First output winding; 12. Second output winding; 13. Input winding; 2. DC bus; 3. Load; 4. First rectifier circuit; 5. Buck converter; 6. Second rectifier circuit; 7. Full-bridge circuit; 8. Filter; 9. Inductor; 10. Capacitor; 31. Support capacitor. Detailed Implementation

[0028] The technical solutions in the embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this specification, and not all embodiments. The specific embodiments described herein are only used to explain this disclosure, and not to limit this disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of this disclosure are within the scope of protection of this disclosure. In addition, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0029] Please see Figure 1 This specification provides a multi-element heterogeneous hydrogen production power supply. The multi-element heterogeneous hydrogen production power supply includes a main branch and an auxiliary branch. One end of the main branch is connected to the first output winding 11 of transformer 1, and the other end is connected to the first end of DC bus 2. One end of the auxiliary branch is connected to the second output winding 12 of transformer 1, and the other end is connected to the first end of DC bus 2. The second end of DC bus 2 is connected to a load 3. The input winding 13 of transformer 1 is connected to the power grid.

[0030] Thus, the multi-element heterogeneous hydrogen production power source draws power from the grid through transformer 1, and after targeted power conversion through the main branch and auxiliary branch, it collaboratively provides the required electrical energy to load 3. The main branch and auxiliary branch are connected to different output windings of transformer 1, which enables independent power supply to the main branch and auxiliary branch, avoiding mutual interference between branches that could lead to power supply instability.

[0031] The input winding 13 of transformer 1 is connected in a star configuration. The input winding 13 is connected to the power grid through filter 8. Filter 8 includes an inductor 81 and a capacitor 82 connected in series. Filter 8 is used to filter high-frequency harmonic components and suppress harmonic interference to the input winding.

[0032] In some embodiments, the main branch is used to supply electrical energy to the DC bus 2. The main branch is used to carry out the main power transmission to provide steady-state power. The main branch may include a first rectifier circuit 4 and a Buck converter 5. The input terminal of the first rectifier circuit 4 is connected to the first output winding 11 of the transformer 1. The output terminal of the first rectifier circuit 4 is connected to the input terminal of the Buck converter 5. The output terminal of the Buck converter 5 is connected to the first end of the DC bus 2.

[0033] The first rectifier circuit 4 can be an uncontrolled rectifier circuit. The uncontrolled rectifier circuit is a diode rectifier circuit. It utilizes the unidirectional conduction characteristic of diodes to convert the AC power output from the first output winding 11 into DC power. For example, the power grid can be a three-phase AC power supply. The first output winding outputs a transformed (e.g., stepped-down) three-phase AC power supply. The uncontrolled rectifier circuit includes three bridge arms. Each bridge arm includes two diodes connected in series. Each bridge arm corresponds to one phase of the three-phase AC power supply. The three bridge arms of the uncontrolled rectifier circuit work together to rectify the three-phase AC power into DC power. The uncontrolled rectifier circuit uses diodes for rectification; the reduced forward voltage of the diodes lowers the conduction losses in the main branch, thereby improving the energy conversion efficiency of the main branch.

[0034] A Buck converter 5, also known as a DC-DC converter or DC-DC converter, converts a higher DC voltage to a lower DC voltage. A Buck converter 5 may include switching transistors, diodes, inductors, and capacitors. The switching transistors can be MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors), IGBTs (Insulated Gate Bipolar Transistors), or IGCTs (Integrated Gate Commutated Thyristors). Taking an IGBT as an example, in the Buck converter 5, the collector of the IGBT is connected to the positive terminal of the output of the first rectifier circuit 4. The emitter of the IGBT is connected to one end of the inductor and the anode of the diode. The other end of the inductor is connected to one end of the capacitor, serving as the positive terminal of the Buck converter 5 output. The other end of the capacitor is connected to the cathode of the diode and the negative terminal of the output of the first rectifier circuit 4, serving as the negative terminal of the Buck converter 5 output. By connecting the input terminal of Buck converter 5 to the output terminal of the first rectifier circuit 4, Buck converter 5 can regulate the DC voltage output by the first rectifier circuit 4. Buck converter 5 can be used for steady-state voltage regulation. However, due to the limitations of the response characteristics of passive components such as inductors and capacitors, the dynamic response of Buck converter 5 is poor.

[0035] In the main branch, the number of the first rectifier circuit 4 and the Buck converter 5 can be one or more, respectively.

[0036] Optionally, transformer 1 can be a phase-shifting transformer. The phase-shifting transformer has multiple first output windings 11. The multiple first output windings 11 have a predetermined phase offset (e.g., 30 degrees). The multiple first output windings 11 can be connected in a star or delta configuration, and the connection methods of different first output windings 11 are different. The main branch can include multiple first rectifier circuits 4. The input terminals of the multiple first rectifier circuits 4 are connected to the multiple first output windings 11 of the phase-shifting transformer. The input terminal of each first rectifier circuit 4 is connected to one first output winding 11 of the phase-shifting transformer. The output terminals of the multiple first rectifier circuits 4 are connected to the input terminal of the Buck converter 5. Thus, by employing multiple first rectifier circuits 4, the characteristic harmonics generated by each first rectifier circuit 4 can cancel each other out, thereby effectively reducing the harmonic content of the output current of the first rectifier circuit 4 and improving the power factor. Furthermore, the multiple first rectifier circuits 4 are connected in parallel to share the output current, reducing the current stress on each first rectifier circuit 4, thereby improving the capacity and reliability of the multi-element heterogeneous hydrogen production power supply.

[0037] by Figure 1 For example, the phase-shifting transformer has two first output windings 11. The phase offset between the two first output windings 11 is 30 degrees. One first output winding 11 is connected in a star configuration, and the other first output winding 11 is connected in a delta configuration. The first output windings 11 can be connected to the input terminal of the first rectifier circuit 4 through an inductor 9.

[0038] Optionally, the main branch may include multiple Buck converters 5. The inputs of the multiple Buck converters 5 are connected in parallel to the output of the first rectifier circuit 4. The outputs of the multiple Buck converters 5 are connected in parallel to the first end of the DC bus 2. The multiple Buck converters 5 can be interleaved. For example, the control signals of the switching transistors in the multiple Buck converters 5 are phase-shifted by a predetermined angle. Thus, by using multi-phase interleaved parallel Buck converters 5, the output current ripple can be reduced.

[0039] Optionally, when the main branch includes multiple first rectifier circuits 4 and multiple Buck converters 5, the input terminals of the multiple first rectifier circuits 4 are connected to multiple first output windings 11 of the phase-shifting transformer. The input terminal of each first rectifier circuit 4 is connected to one first output winding 11 of the phase-shifting transformer. The output terminals of the multiple first rectifier circuits 4 are connected to the input terminals of the multiple Buck converters 5. The output terminals of each first rectifier circuit 4 are connected to the input terminal of one Buck converter 5. The output terminals of the multiple Buck converters 5 are connected in parallel to the first terminal of the DC bus 2.

[0040] In some embodiments, the auxiliary branch can also be used to provide power to the DC bus 2. The auxiliary branch can be used to transmit fluctuating power to compensate for the steady-state power provided by the main branch. Alternatively, the auxiliary branch can also be used to transmit AC excitation to superimpose AC excitation on the steady-state power provided by the main branch. The auxiliary branch may include a second rectifier circuit 6 and a full-bridge circuit 7. The input terminal of the second rectifier circuit 6 is connected to the second output winding 12 of the transformer 1, the output terminal of the second rectifier circuit 6 is connected to the input terminal of the full-bridge circuit 7, and the output terminal of the full-bridge circuit 7 is connected to the first terminal of the DC bus 2. The second output winding 12 can be star-connected. The second output winding 12 can be connected to the input terminal of the second rectifier circuit 6 through an inductor 61. The output terminal of the full-bridge circuit 7 can be connected to the first terminal of the DC bus 2 through an inductor 73.

[0041] The second rectifier circuit 6 is used to convert the AC power output from the second output winding 12 into DC power. The second rectifier circuit 6 can be an uncontrolled rectifier circuit. Alternatively, the second rectifier circuit 6 can be a controlled rectifier circuit. The controlled rectifier circuit includes a PWM (Pulse Width Modulation) rectifier. The controlled rectifier circuit includes switching transistors, with freewheeling diodes connected in anti-parallel. The switching state of the switching transistors is controlled, for example, by a PWM signal. By controlling the switching state of the switching transistors, the controlled rectifier circuit converts AC power into DC power. For example, the power grid is three-phase AC power. The second output winding outputs the transformed three-phase AC power. The controlled rectifier circuit includes three bridge arms. Each bridge arm includes two switching transistors. The two switching transistors are connected in series (the emitter of the upper switching transistor is connected to the collector of the lower switching transistor). Each bridge arm corresponds to one phase of the three-phase AC power. The three bridge arms of the controlled rectifier circuit work together to rectify the three-phase AC power into DC power.

[0042] The full-bridge circuit 7, also known as the H-bridge circuit, may include switching transistors. Please refer to [link / reference]. Figure 2The full-bridge circuit 7 may include two bridge arms, 71 and 72. Each bridge arm includes two switching transistors connected in series (the emitter of the upper switching transistor is connected to the collector of the lower switching transistor). Bridge arm 71 includes switching transistors 711 and 712. Bridge arm 72 includes switching transistors 721 and 722. The high ends of bridge arms 71 and 72 are connected to the positive terminal of the output of the second rectifier circuit 6, and the low ends of bridge arms 71 and 72 are connected to the negative terminal of the output of the second rectifier circuit 6. The midpoint of bridge arm 71 is connected to the positive terminal of the DC bus 2, and the midpoint of bridge arm 72 is connected to the negative terminal of the DC bus 2. The full-bridge circuit 7 can operate in inverter mode. In inverter mode, the full-bridge circuit 7 can invert the DC output of the second rectifier circuit 6 into AC and superimpose it onto the DC bus 2 to achieve superposition of AC excitation. The full-bridge circuit 7 can also operate in chopper mode. In chopper mode, the full-bridge circuit 7 can regulate the DC power output of the second rectifier circuit 6 and output DC power to the DC bus 2 to achieve dynamic compensation of steady-state power.

[0043] The second rectifier circuit 6 and the full-bridge circuit 7 can be connected via capacitor 10.

[0044] The multi-element heterogeneous hydrogen production power supply of this specification includes a main branch and an auxiliary branch, forming a multi-element heterogeneous hybrid topology. In this multi-element heterogeneous hybrid topology, the main branch, based on a first rectifier circuit and a Buck converter, is used to handle the main power transmission, thereby reducing conduction losses and costs and improving energy conversion efficiency. The auxiliary branch, based on a second rectifier circuit and a full-bridge circuit, is used to transmit fluctuating power or AC excitation to achieve precise control and significantly improve dynamic response. Therefore, the multi-element heterogeneous hydrogen production power supply of this specification achieves a balance between steady-state high efficiency and dynamic fast response. In addition, the main branch and the auxiliary branch are connected in parallel to the same DC bus, forming a common bus topology. The common bus topology eliminates the need for isolation inductors or additional series converter stages, reducing size and weight and increasing power density. Furthermore, the common bus topology facilitates reasonable power distribution, improving the integration and reliability of the multi-element heterogeneous hydrogen production power supply.

[0045] In some embodiments, the load 3 includes, but is not limited to, resistors, capacitors, electrical equipment, electrical devices, other power supply devices, etc. Optionally, the load 3 may include an electrochemical load. The electrochemical load may, for example, include a hydrogen electrolyzer, an electroplating tank, etc. Optionally, the multi-element heterogeneous hydrogen production power supply may also include a supporting capacitor 31. The supporting capacitor 31 is connected in parallel between the positive and negative terminals of the DC bus, and thus also in parallel across the load 3. The supporting capacitor 31 is used for filtering.

[0046] In some embodiments, the multi-element heterogeneous hydrogen production power source may further include sensors. The sensors may include current sensors and voltage sensors. The current sensor may include a current transformer, a Hall effect current sensor, a shunt resistor, etc. The current sensor is used to sample current, for example, to sample the load current of load 3, the first output current of the Buck converter 5, and the second output current of the full-bridge circuit 7. The voltage sensor may include a voltage transformer, a voltage divider resistor, etc. The voltage sensor is used to sample voltage, for example, to sample the load voltage across load 3.

[0047] In some embodiments, the multi-element heterogeneous hydrogen production power supply may further include a controller. The controller can be implemented based on discrete components or on integrated circuits such as microprocessors (MCUs), digital signal processors (DSPs), application-specific integrated circuits (ASICs), and programmable logic devices (FPGAs, CPLDs). The controller may include integrated circuits and software running on those integrated circuits. The controller is connected to sensors and can receive electrical signals acquired by the sensors; it can control the multi-element heterogeneous hydrogen production power supply based on these electrical signals, for example, controlling Buck converter 5 and full-bridge circuit 7. The controller can send control signals (e.g., PWM control signals) to Buck converter 5 and full-bridge circuit 7. Control of Buck converter 5 and full-bridge circuit 7 is achieved by controlling the switching states of the switching transistors in Buck converter 5 and full-bridge circuit 7.

[0048] This specification also provides a control method in its embodiments. The control method is used to control a multi-element heterogeneous hydrogen production power source. Please refer to... Figure 3 The control method can be executed by a controller and may specifically include the following steps.

[0049] Step 301: Obtain the load electrical signal of the load; Step 302: Determine the target operating mode of the multi-element heterogeneous hydrogen production power source based on the load electrical signal; Step 303: Control the Buck converter and the full-bridge circuit according to the target operating mode.

[0050] The control method described in this specification can acquire the load electrical signal of the load; determine the target operating mode of the multi-element heterogeneous hydrogen production power supply based on the load electrical signal; and control the Buck converter and the full-bridge circuit based on the target operating mode. Therefore, this specification embodiment can control the power of the main branch and auxiliary branch by controlling the Buck converter and the full-bridge circuit. This allows for adaptive adjustment of the operating state of the main branch and auxiliary branch according to the actual load conditions, ensuring steady-state high-efficiency power output while improving dynamic response speed.

[0051] In some embodiments, a load electrical signal acquired by a sensor may be received. The load electrical signal may include load voltage and load current, wherein the load voltage is the voltage across the load terminals and the load current is the current flowing through the load.

[0052] In some embodiments, a set of conditions may be provided. The set of conditions includes one or more conditions. Each condition corresponds to an operating mode of the multi-element heterogeneous hydrogen production power source. The conditions are used to determine whether the multi-element heterogeneous hydrogen production power source has entered the corresponding operating mode.

[0053] The target condition can be selected from a set of conditions based on the load electrical signal, and the operating mode corresponding to the target condition can be selected as the target operating mode. For example, a voltage change index can be calculated based on the load voltage, and a current change index can be calculated based on the load current; the target condition can be selected from the set of conditions based on both the voltage change index and the current change index. The voltage change index represents the degree of change in load voltage. It can include the voltage change rate and voltage deviation. The voltage change rate is the rate at which the load voltage changes over time. The voltage deviation is the difference between the load voltage and a preset reference voltage. The preset reference voltage can be, for example, the load's rated voltage. The current change index represents the degree of change in load current. It can include the current change rate and current deviation. The current change rate is the rate at which the load current changes over time. The current deviation is the difference between the load current and a preset reference current. The preset reference current can be, for example, the load's rated current.

[0054] For example, the condition set may include condition con1, condition con2, condition con3, condition con4, condition con5, etc. Condition con1 may include: a voltage change index less than or equal to a first threshold, and a current change index less than or equal to a second threshold. Condition con2 may include at least one of the following: a voltage change index greater than or equal to a third threshold, and a current change index greater than or equal to a fourth threshold. Condition con3 may include at least one of the following: a voltage change index greater than the first threshold and less than the third threshold, and a current change index greater than the second threshold and less than the fourth threshold. Condition con4 may include: a load voltage less than or equal to a voltage threshold, and a load current greater than or equal to a current threshold. Condition con5 may include: a voltage change index greater than or equal to the third threshold, a voltage change index greater than the first threshold and less than the third threshold, a current change index greater than or equal to the fourth threshold, and a current change index greater than the second threshold and less than the fourth threshold. The first threshold is less than the third threshold, and the second threshold is less than the fourth threshold. The first threshold and the second threshold may be the same or different. The third threshold and the fourth threshold may be the same or different. For example, the first threshold may be 1%, the second threshold may be 5%, the third threshold may be 10%, and the fourth threshold may be 20%. The current threshold can be, for example, 1.5 times the rated load current. The voltage threshold can be, for example, 0.8 times the rated load voltage. Conditions con1, con2, con3, con4, and con5 correspond to the steady-state mode, dynamic adjustment mode, hybrid modulation mode, fault mode, and electrical excitation superposition mode of the multi-element heterogeneous hydrogen production power source, respectively.

[0055] In some embodiments, condition con1 can be selected as the target condition from the condition set based on the load electrical signal. The target operating mode is steady-state mode. In steady-state mode, the load power is stable, and the multi-element heterogeneous hydrogen production power supply does not require rapid adjustment. Therefore, the first output voltage of the Buck converter can be kept constant, and the switching transistors in the full-bridge circuit can be turned off. For example, the duty cycle of the control signal for the switching transistors in the Buck converter can be kept constant, thus keeping the first output voltage of the Buck converter constant. Alternatively, the duty cycle of the control signal for the switching transistors in the full-bridge circuit can be set to 0, thus turning off the switching transistors in the full-bridge circuit. Thus, the first rectifier circuit (uncontrolled rectifier circuit) can provide the full power of the load. The auxiliary branches do not participate in power transmission. Due to the low forward voltage drop of the diodes, the multi-element heterogeneous hydrogen production power supply has low conduction losses and high energy conversion efficiency. For example, in steady-state mode, the energy conversion efficiency of the multi-element heterogeneous hydrogen production power supply can reach over 97%.

[0056] In some embodiments, condition con2 can be selected as the target condition from the condition set based on the load electrical signal. The target operating mode is a dynamic adjustment mode. In dynamic adjustment mode, the load power changes abruptly, requiring rapid adjustment. For this purpose, the first output current of the Buck converter and the second output current of the full-bridge circuit can be obtained. For example, the first output current and the second output current can be received from a sensor. The bus reference current of the DC bus can be calculated based on the load electrical signal and a preset reference voltage; the bus reference current can be distributed to the main branch and the auxiliary branch according to the power distribution coefficient to obtain the first branch reference current of the main branch and the second branch reference current of the auxiliary branch; the Buck converter can be controlled so that the first output current of the Buck converter reaches the first branch reference current; the full-bridge circuit can be controlled so that the second output current of the full-bridge circuit reaches the second branch reference current. At this time, the full-bridge circuit operates in chopper mode, and the output is adjustable DC.

[0057] The difference between the load voltage and the preset reference voltage can be calculated as the voltage error; the bus reference current can be calculated based on the voltage error. The bus reference current can be understood as the current required to maintain voltage stability across the load. Based on the power distribution factor, the bus reference current can be allocated to the main branch and auxiliary branch, resulting in the first branch reference current of the main branch and the second branch reference current of the auxiliary branch. The sum of the first branch reference current and the second branch reference current equals the bus reference current. For example, , . Indicates the reference current of the first branch. Indicates the reference current of the second branch. Indicates the power distribution factor. This represents the bus reference current. The first current error can be obtained by subtracting the first branch reference current from the current first output current of the Buck converter; the first duty cycle can be calculated based on the first current error; and the switching transistors in the Buck converter can be controlled according to the first control signal to make the first output current of the Buck converter track the first branch reference current. The duty cycle of the first control signal is the first duty cycle. The first control signal can be a PWM control signal, etc. Alternatively, the second current error can be obtained by subtracting the second branch reference current from the current second output current of the full-bridge circuit; the second duty cycle can be calculated based on the second current error; and the switching transistors in the full-bridge circuit can be controlled according to the second control signal to make the second output current of the full-bridge circuit track the second branch reference current. The second control signal can be a PWM control signal, etc. For example, a bipolar method can be used to control the switching transistors in the full-bridge circuit. Figure 2Taking the full-bridge circuit shown as an example, the second control signal may include a first sub-control signal, a second sub-control signal, a third sub-control signal, and a fourth sub-control signal. The first, second, third, and fourth sub-control signals are used to control switches 711, 721, 712, and 722, respectively. The duty cycle of the first and fourth sub-control signals is the second duty cycle, and the duty cycle of the second and third sub-control signals is 1 minus the second duty cycle.

[0058] The first duty cycle and the second duty cycle can be calculated by combining the voltage loop and the current loop. The voltage loop and the current loop are based on a proportional-integral control algorithm.

[0059] The voltage error can be input into the voltage loop to obtain the bus reference current output by the voltage loop. For example, the voltage loop can be configured using the formula... Calculate the reference current for the bus. This represents the bus reference current in the kth sampling period. This represents the voltage loop proportionality coefficient. Indicates the voltage loop integral coefficient. This represents the voltage error in the k-th sampling period. This represents the cumulative sum of voltage errors. Indicates the duration of the sampling period.

[0060] The first current error can be input into the current loop to obtain the first duty cycle of the current loop output. For example, the current loop can be calculated using the formula... Calculate the first duty cycle. This represents the first duty cycle of the k-th sampling period. This represents the proportionality coefficient of the current loop. Indicates the integral coefficient of the current loop. This represents the first current error in the k-th sampling period. This represents the cumulative sum of the first current error. Indicates the duration of the sampling period.

[0061] The second current error can be input into the current loop to obtain the second duty cycle output by the current loop. The process of calculating the second duty cycle based on the second current error is similar to the process of calculating the first duty cycle based on the first current error, and will not be described in detail here.

[0062] The aforementioned power allocation coefficient can be a preset power allocation coefficient. The magnitude of the power allocation coefficient is positively correlated with the power provided by the main branch and negatively correlated with the power provided by the auxiliary branch. In dynamic adjustment mode, the preset power allocation coefficient is less than or equal to a certain threshold. For example, the preset power coefficient can be 0.1, 0.2, etc. Thus, the auxiliary branch transmits most of the power, thereby undertaking most of the dynamic adjustment tasks; the main branch transmits a small portion of the power, thereby assisting in dynamic adjustment. The Buck converter of the main branch has a low bandwidth and a slow dynamic response speed, making it difficult to quickly track dynamic current commands. The auxiliary branch has fast response characteristics. By setting a smaller power allocation coefficient, the dynamic adjustment advantage of the auxiliary branch can be fully utilized to achieve microsecond-level voltage drop suppression and output voltage regulation.

[0063] In some embodiments, condition con3 can be selected as the target condition from the condition set based on the load electrical signal. The target operating mode is a hybrid modulation mode. In the hybrid modulation mode, the load power fluctuates moderately, requiring a balance between energy conversion efficiency and regulation efficiency. Therefore, the first output current of the Buck converter and the second output current of the full-bridge circuit can be obtained. For example, the first output current and the second output current can be received from a sensor. The bus reference current of the DC bus can be calculated based on the load electrical signal and a preset reference voltage; the bus reference current can be distributed to the main branch and auxiliary branch according to the power distribution coefficient to obtain the first branch reference current of the main branch and the second branch reference current of the auxiliary branch; the Buck converter can be controlled so that the first output current of the Buck converter reaches the first branch reference current; the full-bridge circuit can be controlled so that the second output current of the full-bridge circuit reaches the second branch reference current. At this time, the full-bridge circuit operates in chopper mode, outputting adjustable DC.

[0064] The process of calculating the bus reference current, the control process of the Buck converter based on the first branch reference current, and the control process of the full-bridge circuit based on the second branch reference current can be referred to the aforementioned embodiments, and will not be repeated here.

[0065] In hybrid modulation mode, the aforementioned power allocation coefficients can be obtained by querying the power allocation coefficient set based on the load voltage.

[0066] For example, a power allocation coefficient set may include one or more power allocation coefficients. Each power allocation coefficient in the set may be between 0.5 and 0.9. Each power allocation coefficient in the set corresponds to a voltage range and a current range. The voltage and current ranges corresponding to each power allocation coefficient can be obtained experimentally.

[0067] It can determine the target voltage range of the load voltage; it can determine the target current range of the load current; and it can query the power allocation coefficient that corresponds to both the target voltage range and the target current range from the power allocation coefficient set. This power allocation coefficient is the optimal power allocation coefficient for the load under the current operating conditions, which can take into account both energy conversion efficiency and regulation efficiency.

[0068] Of course, in hybrid modulation mode, the power distribution coefficient can also be calculated based on the load voltage.

[0069] For example, an objective function regarding the power allocation coefficient can be constructed based on the load voltage and load current. This objective function represents the losses of the multi-element heterogeneous hydrogen production power source under a given power allocation coefficient. The objective function can be solved to obtain the power allocation coefficient that minimizes the losses of the multi-element heterogeneous hydrogen production power source, which serves as the optimal power allocation coefficient for the load under the current operating conditions. Specific solution methods can include analytical methods or numerical search methods.

[0070] In hybrid modulation mode, by using an appropriate power distribution coefficient, the total load power can be reasonably distributed between the main branch and the auxiliary branch, enabling the main branch and the auxiliary branch to work together efficiently, taking into account both energy conversion efficiency and regulation efficiency.

[0071] In some embodiments, condition con4 can be selected as the target condition from the condition set based on the load electrical signal. The target operating mode is the fault mode. In the fault mode, the output of the multi-element heterogeneous hydrogen production power supply is short-circuited, or the DC bus is over-voltage (or under-voltage). To address this, the switching transistors in the Buck converter can be turned off; the switching transistors in the full-bridge circuit can also be turned off. For example, the duty cycle of the control signal for the switching transistors in the Buck converter can be set to 0, thus turning off the switching transistors in the Buck converter. Similarly, the duty cycle of the control signal for the switching transistors in the full-bridge circuit can be set to 0, thus turning off the switching transistors in the full-bridge circuit. This allows for rapid interruption of the fault current path in a short time, preventing the fault from escalating and protecting power devices from damage caused by overcurrent and overvoltage surges. Furthermore, the synchronous turn-off of the switching transistors in the main branch and auxiliary branch avoids the risk of voltage imbalance and current backflow caused by single-branch operation, achieving system-level fault isolation and reliable protection.

[0072] In some embodiments, the load is an electrochemical load. Condition con5 can be selected as the target condition from a set of conditions based on the load's electrical signal. The target operating mode is an electro-excitation superposition mode. The base voltage and excitation voltage of the load can be determined; the Buck converter can be controlled so that its first output voltage reaches the base voltage; the full-bridge circuit can be controlled so that its second output voltage reaches the excitation voltage. At this time, the full-bridge circuit operates in inverter mode, outputting AC. Thus, in the electro-excitation superposition mode, by controlling the Buck converter to output a DC base voltage, and superimposing a controllable AC excitation voltage by the full-bridge circuit in inverter mode, a composite voltage waveform consisting of a DC base component and an AC excitation component is obtained across the load. This ensures the steady-state energy supply required by the electrochemical load (such as the electrolyzer) and actively improves the charge transfer efficiency on the electrode surface in the electrolyzer through AC excitation, optimizing the electric field distribution at the electrode-electrolyte interface. This effectively suppresses polarization, promotes bubble desorption, and reduces activation overpotential, thereby achieving reduced unit energy consumption, improved electrochemical reaction efficiency, and improved long-term steady-state operation of the electrolyzer while maintaining efficient power transmission in the main branch.

[0073] The base voltage can be determined based on the rated operating voltage of the load. For example, the base voltage can be equal to or less than the rated voltage of the load. The difference between the load voltage and the base voltage can be calculated as the voltage error; a first duty cycle can be calculated based on the voltage error; a first control signal can be generated based on the first duty cycle; the switching transistors in the Buck converter can be controlled based on the first control signal to make the first output voltage of the Buck converter reach the base voltage. The duty cycle of the first control signal is the first duty cycle. The first control signal can be a PWM control signal, etc. For example, the voltage error can be input into the voltage loop to obtain the first duty cycle. For example, the voltage loop can be calculated using the formula... Calculate the first duty cycle. This represents the first duty cycle of the k-th sampling period. This represents the voltage loop proportionality coefficient. Indicates the voltage loop integral coefficient. This represents the voltage error in the k-th sampling period. This represents the cumulative sum of voltage errors. Indicates the duration of the sampling period.

[0074] The excitation parameters of the excitation voltage (e.g., amplitude, frequency, waveform, etc.) can be preset according to the load. For example, a set of excitation parameters (e.g., amplitude 10V, frequency 2kHz, sine wave) can be preset based on the offline test results of the electrochemical load. During operation, the electrochemical load can be monitored in real time, and the preset excitation parameters can be dynamically adjusted to minimize the energy consumption per unit of hydrogen production or maximize the dynamic response, thus obtaining the excitation parameters of the final excitation voltage.

[0075] The AC excitation voltage can be determined based on the preset excitation parameters. . This indicates the amplitude of the AC excitation voltage. The DC bus voltage can be detected using a sensor. . This represents the DC base voltage. The modulation signal can be obtained by dividing the AC excitation voltage by the DC bus voltage. The modulated signal can be compared with a carrier signal (e.g., a triangular carrier signal), and a second control signal can be generated using a bipolar modulation method. The second control signal includes PWM control signals for each switch in the full-bridge circuit. The switches in the full-bridge circuit can be controlled according to the second control signal so that the second output voltage of the full-bridge circuit is the excitation voltage. Figure 2 Taking the full-bridge circuit shown as an example, the second control signal may include a first sub-control signal, a second sub-control signal, a third sub-control signal, and a fourth sub-control signal. The first, second, third, and fourth sub-control signals are used to control switches 711, 721, 712, and 722, respectively. The duty cycle of the first and fourth sub-control signals is D1. D1 is obtained by comparing the modulation signal with the carrier signal. The duty cycle of the second and third sub-control signals is D2. D2 = 1 - D1.

[0076] This specification also provides a controller, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the above-described control method.

[0077] This specification also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described control method.

[0078] This specification also provides a computer program product, which includes a computer program that, when executed by a processor, implements the above-described control method.

[0079] The functional units in the embodiments of this specification can be integrated into one processing unit, or each functional unit can exist physically separately, or two or more functional units can be integrated into one processing unit.

[0080] Those skilled in the art will understand that the descriptions of the various embodiments in this specification have different focuses, and parts not described in detail in a certain embodiment can be referred to in the relevant descriptions of other embodiments. Furthermore, it is understood that those skilled in the art, after reading this specification, can conceive of any combination of some or all of the embodiments listed in this specification without creative effort, and such combinations are also within the scope of disclosure and protection of this specification.

[0081] Although this specification has been described through embodiments, those skilled in the art will understand that the above embodiments are merely illustrative of the core ideas of this specification. Those skilled in the art will appreciate that many variations and modifications are possible with this specification. It is intended that the appended claims encompass these variations and modifications without departing from the spirit of this specification.

Claims

1. A multi-element heterogeneous hydrogen production power source, characterized in that, The multi-element heterogeneous hydrogen production power source includes a main branch and an auxiliary branch connected in parallel to the same DC bus; The main branch includes a first rectifier circuit and a Buck converter. The input terminal of the first rectifier circuit is connected to the first output winding of the transformer, and the output terminal of the first rectifier circuit is connected to the input terminal of the Buck converter. The output terminal of the Buck converter is connected to the first end of the DC bus. The main branch is used to provide steady-state power to the DC bus. The first rectifier circuit is an uncontrolled rectifier circuit. The auxiliary branch includes a second rectifier circuit and a full-bridge circuit. The input terminal of the second rectifier circuit is connected to the second output winding of the transformer, and the output terminal of the second rectifier circuit is connected to the input terminal of the full-bridge circuit. The output terminal of the full-bridge circuit is connected to the first terminal of the DC bus. The auxiliary branch is used to transmit fluctuating power or AC excitation. The second terminal of the DC bus is connected to the load, which is a hydrogen electrolyzer. The full-bridge circuit can operate in chopper mode or inverter mode; The chopping mode is used to transmit fluctuating power in the auxiliary branch. When operating in chopping mode, the full-bridge circuit regulates the DC power output by the second rectifier circuit and outputs DC power to the DC bus to compensate for the steady-state power provided by the main branch. The inverter mode is used to transmit AC excitation in the auxiliary branch. When operating in inverter mode, the full-bridge circuit inverts the DC power output from the second rectifier circuit into AC power and outputs AC power to the DC bus, so as to superimpose AC excitation on the steady-state power provided by the main branch.

2. The multi-element heterogeneous hydrogen production power source according to claim 1, characterized in that, The input winding of the transformer is connected to the power grid; the full-bridge circuit is an IGBT full-bridge circuit.

3. The multi-element heterogeneous hydrogen production power source according to claim 1, characterized in that, The transformer is a phase-shifting transformer; the main branch includes multiple first rectifier circuits, the input terminals of the multiple first rectifier circuits are connected to multiple first output windings of the phase-shifting transformer, and the output terminals of the multiple first rectifier circuits are connected to the input terminals of the Buck converter.

4. The multi-element heterogeneous hydrogen production power source according to claim 1, characterized in that, The main branch includes multiple Buck converters. The output terminal of the first rectifier circuit is connected to the input terminal of the multiple Buck converters, and the output terminal of the multiple Buck converters is connected to the first terminal of the DC bus.

5. A control method, characterized in that, The control method is applied to the multi-component isomeric hydrogen production power source according to any one of claims 1-4; the control method includes: Obtain the load electrical signal of the load; The target operating mode of the multi-component heterogeneous hydrogen production power source is determined based on the load electrical signal. The Buck converter and the full-bridge circuit are controlled according to the target operating mode.

6. The method according to claim 5, characterized in that, Determining the operating mode of the multi-element heterogeneous hydrogen production power source includes: The target condition is selected from the set of conditions based on the load electrical signal. The condition set includes multiple conditions, and the conditions in the condition set correspond to the working modes of the multi-component heterogeneous hydrogen production power source. The target working mode is the working mode corresponding to the target conditions.

7. The method according to claim 5, characterized in that, The target operating mode is a steady-state mode; The control of the Buck converter and the full-bridge circuit includes: The first output voltage of the Buck converter is kept constant. The switching transistors in the full-bridge circuit are turned off.

8. The method according to claim 7, characterized in that, The load electrical signal includes load voltage and load current; Determining the target operating mode of the multi-element heterogeneous hydrogen production power source includes: The voltage change index is determined based on the load voltage, and the current change index is determined based on the load current. When the voltage change index is less than or equal to the first threshold and the current change index is less than or equal to the second threshold, the target operating mode of the multi-element heterogeneous hydrogen production power source is determined to be the steady-state mode.

9. The method according to claim 5, characterized in that, The method further includes: Obtain the first output current of the Buck converter and the second output current of the full-bridge circuit; The control of the Buck converter and the full-bridge circuit includes: Calculate the bus reference current of the DC bus based on the load electrical signal and the preset reference voltage; According to the power allocation factor, the bus reference current is allocated to the main branch and the auxiliary branch to obtain the first branch reference current of the main branch and the second branch reference current of the auxiliary branch. The Buck converter is controlled so that its first output current reaches the first branch reference current, and the full-bridge circuit is controlled so that its second output current reaches the second branch reference current.

10. The method according to claim 9, characterized in that, The target operating mode is a dynamic adjustment mode, and the power allocation coefficient is a preset power allocation coefficient; The load electrical signal includes load voltage and load current; Determining the target operating mode of the multi-element heterogeneous hydrogen production power source includes: The voltage change index is determined based on the load voltage, and the current change index is determined based on the load current. The target operating mode of the multi-element heterogeneous hydrogen production power source is determined to be the dynamic adjustment mode when at least one of the following conditions is met: the voltage change index is greater than or equal to the third threshold, and the current change index is greater than or equal to the fourth threshold.

11. The method according to claim 9, characterized in that, The load electrical signal includes load voltage and load current; the target operating mode is a hybrid modulation mode; the power allocation coefficient is obtained by querying the power allocation coefficient set based on the load voltage, or the power allocation coefficient is calculated based on the load voltage. Determining the target operating mode of the multi-element heterogeneous hydrogen production power source includes: The voltage change index is determined based on the load voltage, and the current change index is determined based on the load current. The target operating mode of the multi-element heterogeneous hydrogen production power source is determined to be a hybrid modulation mode when at least one of the following conditions is met: the voltage change index is greater than a first threshold and less than a third threshold, and the current change index is greater than a second threshold and less than a fourth threshold.

12. The method according to claim 5, characterized in that, The target operating mode is a fault mode; The control of the Buck converter and the full-bridge circuit includes: Control the switching transistors in the Buck converter to turn off; The switching transistors in the full-bridge circuit are turned off.

13. The method according to claim 12, characterized in that, The load electrical signal includes load voltage and load current; determining the target operating mode of the multi-element heterogeneous hydrogen production power source includes: The target operating mode of the multi-element heterogeneous hydrogen production power source is determined to be a fault mode when at least one of the following conditions is met: the load voltage is less than or equal to the voltage threshold, or the load current is greater than or equal to the current threshold.

14. The method according to claim 5, characterized in that, The target operating mode is an electrically excited superimposed mode; The control of the Buck converter and the full-bridge circuit includes: Determine the base voltage and excitation voltage of the load; Control the Buck converter so that the first output voltage of the Buck converter reaches the base voltage; The full-bridge circuit is controlled so that the second output voltage of the full-bridge circuit reaches the excitation voltage.

15. The method according to claim 14, characterized in that, The load is a hydrogen electrolyzer, and the load electrical signal includes load voltage and load current; determining the target operating mode of the multi-element heterogeneous hydrogen production power source includes: The voltage change index is determined based on the load voltage, and the current change index is determined based on the load current. The target operating mode of the multi-element heterogeneous hydrogen production power source is determined to be the electrically excited superposition mode when at least one of the following conditions is met: the voltage change index is greater than or equal to the third threshold, the voltage change index is greater than the first threshold and less than the third threshold, the current change index is greater than or equal to the fourth threshold, and the current change index is greater than the second threshold and less than the fourth threshold.

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