Soft start method, power conversion system and household energy storage system

Abstract

The application discloses a soft starting method, a power conversion system and a household energy storage system, and is applied to the technical field of household energy storage, and is used for improving the soft starting effect of a full-bridge resonant converter. The method provided by the application comprises the following steps: a soft starting process is configured as a plurality of working periods, the duty cycle is adjusted in segments to gradually increase, the output voltage is slowly output and gradually increased in value according to the transformation of the duty cycle in the soft starting process, the working current in the soft starting process can be effectively controlled, the voltage stress of a power switch tube when hard turning off is weakened, the risk that the voltage stress of the power switch tube exceeds the specification in the soft starting process and causes failure is reduced, and the soft starting effect of the circuit is improved.

Description

Technical Field

[0001] This application relates to the field of residential energy storage technology, and in particular to a soft-start method, a power conversion system, and a residential energy storage system. Background Technology

[0002] Resonant converters enable zero-voltage turn-on of round-edge power switching devices and zero-current turn-off of complex power switches. They can operate at very high switching frequencies, significantly improving converter efficiency and power density. These resonators have high efficiency at their resonant frequency and have been widely used in recent years.

[0003] When a resonant converter starts up, the presence of the secondary-side output capacitor means that starting directly at the resonant frequency would be equivalent to a short circuit, easily damaging components such as the switching transistors and resonant capacitors. Current technology generally uses a soft-start method to start the resonant converter. The existing methods mainly fall into two categories: one is based on a fixed frequency, linearly increasing the duty cycle. If the linear ratio is set too large, the soft-start time will be too long; if the linear ratio is set too small, the hard-turn-off current of the switching transistors will be too large. The other method is to fix the duty cycle and control the switching frequency, but this results in a higher overall circuit complexity. Summary of the Invention

[0004] This application provides a soft-start method, a power conversion system, and a residential energy storage system to reduce the complexity of soft-starting resonant converters.

[0005] A soft-start method is applied to a full-bridge resonant converter, the full-bridge resonant converter including a first switch, a second switch, a third switch, and a fourth switch, comprising:

[0006] The first switch and the fourth switch are simultaneously turned on or off, and the second switch and the third switch are simultaneously turned on or off; during the soft start process, the switching cycles of the first switch, the second switch, the third switch, and the fourth switch remain unchanged; the soft start process is configured with N working periods, where N≥2;

[0007] During the k-th working period, 1≤k≤N-1, the duty cycles of the first switch, the second switch, the third switch, and the fourth switch remain unchanged or gradually increase;

[0008] In the (k+1)th working period, the duty cycle of the first switch, the second switch, the third switch, and the fourth switch is greater than the duty cycle of the first switch, the second switch, the third switch, and the fourth switch in the kth working period;

[0009] During the Nth working period, the duty cycles of the first switch, the second switch, the third switch, and the fourth switch gradually increase to their maximum values.

[0010] When the duty cycles of the first, second, third, and fourth switches reach their maximum values, the output voltage of the full-bridge resonant converter increases to its steady-state value.

[0011] A power conversion system, the power converter including a full-bridge resonant converter, the full-bridge resonant converter being configured to perform a soft-start using the soft-start method described above.

[0012] A residential energy storage system includes a cloud platform, an energy management system, a power conversion system, and a battery management system. The power conversion system includes a full-bridge resonant converter, which is configured to perform a soft-start using the aforementioned soft-start method.

[0013] The soft-start method, power conversion system, and residential storage system provided in this application configure the soft-start process of the full-bridge resonant converter into multiple operating periods, control the duty cycle of the full-bridge resonant converter to gradually increase to the maximum duty cycle value, more effectively control the operating current of the full-bridge resonant converter during the soft-start process, thereby reducing the voltage stress of the power switch during hard turn-off, reducing the risk of failure caused by stress exceeding specifications during the soft-start process of the main power switch, and reducing the complexity of the soft-start process. Attached Figure Description

[0014] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a flowchart of a soft-start method according to an embodiment of this application;

[0016] Figure 2 This is a schematic diagram of a soft-start method in one embodiment of this application;

[0017] Figure 3 This is a schematic diagram of a soft-start method in another embodiment of this application;

[0018] Figure 4 This is a schematic diagram of a soft-start method in one embodiment of this application;

[0019] Figure 5 This is a circuit diagram of a full-bridge resonant converter in one embodiment of this application;

[0020] Figure 6 This is a schematic diagram of the structure of a residential energy storage system in one embodiment of this application. Detailed Implementation

[0021] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein in the specification of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "comprising" and "having," and any variations thereof, in the specification, claims, and foregoing drawings of this application, are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the specification, claims, or foregoing drawings of this application are configured to distinguish different objects, rather than to describe a particular order.

[0023] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0024] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0025] like Figure 1As shown, this application provides a soft-start method. The real-time hardware environment of this method is a residential energy storage system, which is equipped with a computer that stores and executes computer instructions. The computer hardware includes, but is not limited to, microprocessors, application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), digital signal processors (DSPs), embedded devices, etc. The form of the computer is not limited to desktop computers, laptops, handheld computers, and cloud servers.

[0026] This method is applied to a full-bridge resonant converter, which includes a first switch, a second switch, a third switch, and a fourth switch.

[0027] S10, the first and fourth switches are simultaneously turned on or off, and the second and third switches are simultaneously turned on or off; during the soft start process, the switching cycles of the first, second, third, and fourth switches remain unchanged; the soft start process is configured with N working periods, where N≥2;

[0028] Specifically, during the soft-start process, the switching cycles of the first, second, third, and fourth switches remain unchanged. In each switching cycle, the first and fourth switches are simultaneously turned on or off, and the second and third switches are simultaneously turned on or off. Within each switching cycle, the first and fourth switches are first turned on simultaneously, and after a first on-time, they are simultaneously turned off. At a preset node, the second and third switches are simultaneously turned on, and after a first on-time, they are simultaneously turned off.

[0029] The soft-start process is configured into N working periods, each of which includes a preset number of switching cycles. The number of switching cycles in each working period gradually increases in chronological order.

[0030] It should be noted that the number of segments in the soft-start process can be adjusted according to actual needs to effectively control the operating current of the soft-start process.

[0031] S20, during the k-th working period, 1≤k≤N-1, the duty cycles of the first, second, third, and fourth switches remain unchanged or gradually increase;

[0032] Specifically, the duty cycle represents the proportion of the switching time of the transistor to the switching cycle T. In this scheme, the switching time of the transistor is equal to the sum of the switching times of the first and fourth transistors plus the switching times of the second and third transistors.

[0033] The k-th working period includes multiple switching cycles. The fact that the duty cycles of the first, second, third, and fourth switches remain unchanged indicates that the conduction time of the first, second, third, and fourth switches is the same in each switching cycle. The fact that the duty cycles of the first, second, third, and fourth switches gradually increase indicates that the conduction time of the first, second, third, and fourth switches gradually increases in each switching cycle.

[0034] S30, in the (k+1)th working period, the duty cycles of the first, second, third, and fourth switching transistors are greater than the duty cycles of the first, second, third, and fourth switching transistors in the kth working period;

[0035] Specifically, at the beginning of the (k+1)th working period, the duty cycles of the first, second, third, and fourth switching transistors are greater than those at the end of the kth working period.

[0036] Understandably, at the end of the k-th working period, the duty cycles of the first, second, third, and fourth switches are D. k Then, during the (k+1)th working period, the duty cycles of the first, second, third, and fourth switches are determined by D. k Increase to D k+1 , where D k <D k+1 .

[0037] It should be noted that during the (k+1)th working period, the duty cycles of the first, second, third, and fourth switching transistors are determined by D. k Gradually increasing to D according to a linear relationship k+1 Alternatively, at the start of the (k+1)th working period, the duty cycle increases to D. k+1 And maintain a duty cycle of D k+1 .

[0038] S40, during the Nth working period, the duty cycles of the first, second, third, and fourth switching transistors gradually increase to their maximum values;

[0039] Specifically, during the last working period of the soft-start process, the duty cycles of the first, second, third, and fourth switching transistors are increased to their maximum value Dmax.

[0040] When the duty cycles of the first, second, third, and fourth switches reach their maximum values, the output voltage of the full-bridge resonant converter increases to its steady-state value.

[0041] Specifically, when the duty cycles of the first, second, third, and fourth switches increase to their maximum values, the output voltage V of the full-bridge resonant converter... out Once the steady-state value is reached, the soft-start process ends. In this embodiment, by configuring the soft-start process into multiple operating periods and gradually increasing the duty cycle in segments, the output voltage is slowly increased according to the change in duty cycle during the soft-start process. This effectively controls the operating current during the soft-start process, thereby reducing the voltage stress on the power switch during hard turn-off, reducing the risk of the power switch failing due to excessive voltage stress during the soft-start process, and improving the soft-start effect of the circuit.

[0042] In this embodiment, as an optional implementation, the conduction duration of the first and fourth switching transistors is equal to the conduction duration of the second and third switching transistors in each switching cycle.

[0043] Specifically, the working period includes a preset number of switching cycles. In each switching cycle, the conduction time of the first and fourth switching transistors is equal to the conduction time of the second and third switching transistors.

[0044] In this embodiment, the first and fourth switching transistors are set to have the same conduction time as the second and third switching transistors, which is effective in controlling the duty cycle to change slowly in segments, thereby effectively increasing the operating current.

[0045] In this embodiment, as an optional implementation, from the first working period to the (N-1)th working period, the duty cycle of the first switch, the second switch, the third switch, and the fourth switch remains unchanged in each working period; the duty cycle of the first switch, the second switch, the third switch, and the fourth switch increases by Δd between two adjacent working periods, and Δd gradually increases.

[0046] Specifically, during the soft start process, it is configured into N working periods. In each working period from the first working period to the (N-1)th working period, the duty cycle of the first, second, third, and fourth switching transistors remains unchanged. In two adjacent working periods, the duty cycle of the first, second, third, and fourth switching transistors increases by an increase of Δd.

[0047] During the N-1 working periods, the duty cycles of the first, second, third, and fourth switching transistors increase to their maximum values.

[0048] In each working period and each switching cycle, the conduction time of the first, second, third, and fourth switching transistors is the same, thus ensuring that the duty cycle remains unchanged in each working period.

[0049] In adjacent working periods, the conduction duration of the first, second, third, and fourth switching transistors in each switching cycle is increased in the next working period, thereby increasing the duty cycle of the first, second, third, and fourth switching transistors.

[0050] In this embodiment, the duty cycles of the first, second, third, and fourth switching transistors increase in a jump manner, taking working time periods as the unit. That is, at the boundary between two adjacent working time periods, the duty cycles of the first, second, third, and fourth switching transistors increase in a jump manner.

[0051] For example, in the first working period, the duty cycle of the first, second, third, and fourth switching transistors is d1, and in the second working period, the duty cycle of the first, second, third, and fourth switching transistors is d2. From the last switching cycle of the first working period to the first switching cycle of the second working period, the duty cycle of the first, second, third, and fourth switching transistors increases linearly from d1 to d2. The duty cycle increase in other working periods follows the same principle and will not be elaborated further here.

[0052] In this embodiment, the soft-start process is configured into N working periods. In each working period, the duty cycle of the first, second, third, and fourth switching transistors is kept constant, so that the output voltage increases slowly over a certain period of time and then increases rapidly to the steady-state value. During this process, the operating current of the full-bridge resonant converter can be effectively controlled during the soft-start process, and the voltage stress of the power switching transistors during the hard turn-off process can be reduced.

[0053] In this embodiment, as Figure 2 As shown, as an optional implementation, the soft-start process is configured to have four working periods;

[0054] During the first working period, the duty cycle of the first, second, third, and fourth switching transistors is B1 and remains unchanged.

[0055] During the second operating period, the duty cycle of the first, second, third, and fourth switching transistors is B2 and remains unchanged.

[0056] During the third working period, the duty cycle of the first, second, third, and fourth switching transistors is B3 and remains unchanged.

[0057] During the fourth operating period, the duty cycles of the first, second, third, and fourth switching transistors gradually increase to the maximum value B4.

[0058] B4>B3>B2>B1.

[0059] Specifically, during the first working period [0, t1], the duty cycle of the first, second, third, and fourth switching transistors remains at B1. During the second working period [t1, t2], the duty cycle of the first, second, third, and fourth switching transistors remains at B2.

[0060] At time t1, the duty cycle of the first, second, third, and fourth switching transistors increases from B1 to B2.

[0061] During the third working period [t2, t3], the duty cycle of the first, second, third, and fourth switches remains at B3.

[0062] At time t2, the duty cycle of the first, second, third, and fourth switching transistors increases from B2 to B3.

[0063] During the fourth working period [t3, t4], the duty cycle of the first, second, third, and fourth switching transistors gradually increases from B3 to the maximum value B4.

[0064] At time t4, the duty cycle of the first, second, third, and fourth switching transistors increases to B4.

[0065] During the first, second, and third working periods, the duty cycles of the first, second, third, and fourth switching transistors remain constant. Between adjacent working periods, the duty cycle increases by a certain amount. The change in duty cycle during each working period can be expressed by the following formula:

[0066] B1+Δd1=B2

[0067] B2+Δd2=B3

[0068] B3+K1t=B4

[0069] Where t represents the conduction duration of the first, second, third, and fourth switches during the fourth working period, K1 represents the growth rate of the duty cycle during the fourth working period, Δd1 represents the increase in the duty cycle between the first and second working periods, and Δd2 represents the increase in the duty cycle between the second and third working periods.

[0070] It should be noted that duty cycle represents the proportion of the time each switch is on within the entire switching cycle. Understandably, the longer the switch is on in each switching cycle, the larger the corresponding duty cycle.

[0071] In this embodiment, each working period includes a preset number of switching cycles. The sum of the conduction durations of the first switch, the second switch, the third switch, and the fourth switch in each switching cycle is recorded as the total conduction duration of the working period.

[0072] During the first working period, the first, second, third, and fourth switching transistors have the same conduction duration in each switching cycle, so the duty cycle remains at B1 during the first working period.

[0073] During the second working period, the first, second, third, and fourth switching transistors have the same conduction duration in each switching cycle, and the duty cycle remains at B2.

[0074] During the third working period, the first, second, third, and fourth switching transistors have the same on-time in each switching cycle, so the duty cycle remains at B3.

[0075] During the fourth working period, the conduction duration of the first, second, third, and fourth switching transistors gradually increases in each switching cycle. The conduction duration of the previous switching cycle is less than that of the next switching cycle. By increasing the conduction duration of the first, second, third, and fourth switching transistors in each switching cycle, the duty cycle gradually increases from B3 to the maximum value B4 during the fourth working period.

[0076] In this embodiment, the duty cycle during the soft-start process is controlled in segments. By keeping the duty cycle constant, the growth rate of the output voltage is controlled during this period. The output voltage is slowly built up in the early stage, reducing voltage stress and minimizing the risk of circuit failure.

[0077] In this embodiment, as an optional implementation, the duty cycles of the first, second, third, and fourth switching transistors gradually increase during the k-th working period; the increase in the duty cycles of the first, second, third, and fourth switching transistors during the (k+1)-th working period is greater than the increase during the k-th working period.

[0078] Specifically, within k working periods, the duty cycles of the first, second, third, and fourth switching transistors increase linearly in a piecewise manner. In the first working period, the duty cycles of the first, second, third, and fourth switching transistors gradually increase from their initial values; and the growth rate of the duty cycle gradually increases in each working period until the duty cycle increases to its maximum value.

[0079] In this embodiment, by controlling the growth rate of the duty cycle of the first, second, third, and fourth switching transistors in each working period, the growth rate of the output voltage is adjusted, thereby adjusting the start-up rate of the full-bridge resonant converter, reducing the voltage stress of the switching transistors during hard shutdown during soft start-up, and improving the soft start effect.

[0080] In this embodiment, as Figure 3 As shown, as an optional implementation, the soft-start process is configured to have three working periods;

[0081] During the first working period, the duty cycles of the first, second, third, and fourth switching transistors gradually increase from 0 to C1;

[0082] During the second working period, the duty cycles of the first, second, third, and fourth switching transistors gradually increase from C1 to C2.

[0083] During the third working period, the duty cycles of the first, second, third, and fourth switching transistors gradually increase from C2 to the maximum value C3.

[0084] C3>C2>C1.

[0085] Specifically, during the first working period [0, t1], the duty cycles of the first, second, third, and fourth switching transistors gradually increase from 0 to C1;

[0086] During the second working period [t1, t2], the duty cycle of the first, second, third, and fourth switching transistors gradually increases from C1 to C2.

[0087] During the third operating period [t2, t3], the duty cycles of the first, second, third, and fourth switching transistors gradually increase from C2 to their maximum value C3. When the duty cycle reaches its maximum value, the output voltage gradually increases until it reaches a steady-state value.

[0088] The change in duty cycle during each working period can be expressed by the following formula:

[0089] C1=K2*t

[0090] C2 = K3*t + C1

[0091] C3 = K4*t + C2

[0092] Where K2 represents the duty cycle growth rate of the first working period, K3 represents the duty cycle growth rate of the second working period, and K4 represents the duty cycle growth rate of the third working period. t represents the conduction duration of the first, second, third, and fourth switching transistors in each switching cycle.

[0093] As a preferred implementation, K4>K3>K2.

[0094] Within each working period, the conduction duration of the first, second, third, and fourth switching transistors gradually increases, taking the switching cycle as the unit. For example, in the first switching cycle of the first working period, the conduction duration of the first, second, third, and fourth switching transistors is a1, and in the second switching cycle of the first working period, the conduction duration of the first, second, third, and fourth switching transistors is a2, and a2>a1.

[0095] It should be noted that, in this embodiment, the conduction duration of the last switching cycle of the first working period is less than the conduction duration of the first working cycle of the second working period, and the conduction duration of the last switching cycle of the second working period is less than the conduction duration of the first switching cycle of the third working period.

[0096] In this embodiment, by controlling the duty cycles of the first, second, third, and fourth switching transistors to increase linearly in segments, the output voltage is effectively controlled to increase to a steady-state value at a certain growth rate, quickly reaching the start-up voltage, achieving soft start, ensuring the start-up effect of the soft start process, and reducing the risk of circuit failure caused by exceeding specifications.

[0097] In this embodiment, as an optional implementation, N working periods are configured as a first stage and a second stage; in the first stage, the duty cycle of the first switch, the second switch, the third switch, and the fourth switch remains unchanged in each working period; in the second stage, the duty cycle of the first switch, the second switch, the third switch, and the fourth switch gradually increases in each working period.

[0098] Specifically, the soft-start process is configured into a first stage and a second stage. The first stage includes at least one working period. In each working period of the first stage, the duty cycle of the first switch, the second switch, the third switch, and the fourth switch remains unchanged. The duty cycle of the first switch, the second switch, the third switch, and the fourth switch increases as the working period increases.

[0099] The second stage includes at least one working period, during which the first, second, third, and fourth switching transistors gradually increase in a linear fashion.

[0100] The duty cycle remains constant during a working period, and the duty cycle is increased at a certain rate in the first stage. The output voltage is increased slowly in the first stage, and the duty cycle is controlled to increase linearly in the second stage, which accelerates the increase of output voltage to a certain extent and speeds up the start-up time of the soft start process.

[0101] In this embodiment, as Figure 4 As shown, as an optional implementation, the soft-start method is configured with three working periods;

[0102] During the first working period, the duty cycle of the first, second, third, and fourth switching transistors is E1 and remains unchanged.

[0103] During the second working period, the duty cycle of the first, second, third, and fourth switching transistors gradually increases from E1 to E2.

[0104] During the third working period, the duty cycle of the first, second, third, and fourth switching transistors gradually increases from E2 to the maximum value E3.

[0105] E3>E2>E1.

[0106] Specifically, during the first working period [0, t1], the duty cycle of the first, second, third, and fourth switching transistors remains at E1;

[0107] During the second working period [t1, t2], the duty cycles of the first, second, third, and fourth switching transistors gradually increase from E1 to E2. During the second working period, the duty cycles of the first, second, third, and fourth switching transistors increase linearly.

[0108] During the third operating period [t2, t3], the duty cycles of the first, second, third, and fourth switching transistors gradually increase from E2 to the maximum value E3, and the output voltage gradually increases to the steady-state value.

[0109] In a preferred embodiment, the first working period is set as the first stage, in which the duty cycle of the first, second, third, and fourth switching transistors remains constant in units of working periods; the second and third working periods are set as the second stage, in which the duty cycle of the first, second, third, and fourth switching transistors gradually increases to the regulated value.

[0110] In the second stage, the duty cycle of the first, second, third, and fourth switching transistors increases slowly during the second working period, which is used to slowly increase the output voltage. In the third working period, the duty cycle of the first, second, third, and fourth switching transistors increases rapidly, which is used to quickly increase the output voltage to the steady-state value, so as to speed up the start-up time of the soft start process.

[0111] In this embodiment, by setting the soft-start process into a first stage and a second stage, the duty cycle growth rate of the first, second, third, and fourth switching transistors is kept constant during the first stage. By segmenting the duty cycle growth of the first, second, third, and fourth switching transistors or linearly adjusting the duty cycle growth, the growth rate of the output voltage is adjusted, effectively controlling the increase rate of the operating current during the soft-start process and reducing the risk of circuit failure due to voltage stress.

[0112] In this embodiment, as an optional implementation, the first and fourth switching transistors are turned on by a first driving signal, and the second and fourth switching transistors are turned on by a second driving signal; wherein the first driving signal and the second driving signal have the same frequency and are 180° out of phase.

[0113] Specifically, the first driving signal is used to turn on the first and fourth switching transistors, and the second driving signal is used to turn on the second and third switching transistors. The first driving signal and the second driving signal have the same frequency but are 180° out of phase.

[0114] In this embodiment, the first switch, the fourth switch, the second switch, and the third switch are driven by drive signals with a phase difference of 180° respectively to establish the output voltage.

[0115] This application provides a power conversion system including a full-bridge resonant converter, which is configured to perform a soft-start using the soft-start method described above.

[0116] Specifically, the circuit structure of the full-bridge resonant converter is as follows: Figure 5 As shown, the full-bridge resonant converter consists of a first switch Q1, a second switch Q2, a third switch Q3, a fourth switch Q4, a transformer L1, and a rectifier circuit. The first switch Q1 and the third switch are located on the first bridge arm, and the second switch Q3 and the fourth switch are located on the second bridge arm. The first bridge arm and the second bridge arm are connected in parallel. The first bridge arm and the second bridge arm are respectively connected to the transformer.

[0117] The rectifier circuit consists of power diodes D1, D2, D3, and D4, and an output capacitor Cout. The rectifier circuit is located on the secondary output side of transformer L1. The secondary output side of transformer L1 also includes a resonant inductor Lr and a resonant capacitor Cr.

[0118] The primary side of transformer L1 is connected to the magnetizing inductor Lm.

[0119] Specifically, the soft-start process of this full-bridge resonant converter is configured as follows:

[0120] The first switch Q1 and the fourth switch Q4 are simultaneously turned on or off, and the second switch Q2 and the third switch Q3 are simultaneously turned on or off. During the soft start process, the switching cycles of the first switch Q1, the second switch Q2, the third switch Q3, and the fourth switch Q4 remain unchanged. The soft start process is configured with N working periods, where N≥2.

[0121] During the k-th working period, 1≤k≤N-1, the duty cycles of the first switch Q1, the second switch Q2, the third switch Q3, and the fourth switch Q4 remain unchanged or gradually increase;

[0122] During the (k+1)th working period, the duty cycles of the first switch Q1, the second switch Q2, the third switch Q3, and the fourth switch Q4 are greater than the duty cycles of the first switch Q1, the second switch Q2, the third switch Q3, and the fourth switch Q4 during the kth working period.

[0123] During the Nth working period, the duty cycles of the first switch Q1, the second switch Q2, the third switch Q3, and the fourth switch Q4 gradually increase to their maximum values.

[0124] When the duty cycles of the first switch Q1, the second switch Q2, the third switch Q3, and the fourth switch Q4 reach their maximum values, the output voltage of the full-bridge resonant converter increases to its steady-state value.

[0125] This application provides a residential energy storage system, such as... Figure 6 As shown, it includes a cloud platform, an energy management system, a power conversion system, and a battery management system. The power conversion system includes a full-bridge resonant converter, which is configured to perform a soft start using the aforementioned soft start method.

[0126] The cloud platform provides computing, networking, and storage capabilities based on hardware and software resources. The EMS (Energy Management System) is used for the rational planning and utilization of energy, reducing energy consumption per unit of product. The PCS (Unit of Power Converter System) converts AC power into DC voltage for battery charging and converts the battery's DC power into AC power suitable for grid connection and household use during battery discharge, ensuring power parameters meet system requirements and providing power communication and information acquisition capabilities. The BMS (Battery Management System) is a unit device for managing battery charging and discharging and acquiring signals.

[0127] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when the computer program is executed, it can include the processes of the embodiments of the methods described above.

[0128] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is used as an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above.

[0129] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application 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 this application, and should all be included within the protection scope of this application.

Claims

1. A soft-start method applied to a full-bridge resonant converter, the full-bridge resonant converter comprising a first switch, a second switch, a third switch, and a fourth switch, characterized in that: The first switch and the fourth switch are simultaneously turned on or off, and the second switch and the third switch are simultaneously turned on or off; during the soft start process, the switching cycles of the first switch, the second switch, the third switch, and the fourth switch remain unchanged; the soft start process is configured with N working periods, where N≥2; During the k-th working period, 1≤k≤N-1, the duty cycles of the first switch, the second switch, the third switch, and the fourth switch remain unchanged or gradually increase; In the (k+1)th working period, the duty cycle of the first switch, the second switch, the third switch, and the fourth switch is greater than the duty cycle of the first switch, the second switch, the third switch, and the fourth switch in the kth working period; During the Nth working period, the duty cycles of the first switch, the second switch, the third switch, and the fourth switch gradually increase to their maximum values. When the duty cycles of the first, second, third, and fourth switches reach their maximum values, the output voltage of the full-bridge resonant converter increases to a steady-state value. From the first working period to the (N-1)th working period, the duty cycles of the first, second, third, and fourth switches remain unchanged in each working period. The duty cycle increase of the first, second, third, and fourth switches in two adjacent working periods is Δd, and Δd gradually increases.

2. The soft-start method according to claim 1, characterized in that, During each switching cycle, the conduction duration of the first switch and the fourth switch is equal to the conduction duration of the second switch and the third switch.

3. The soft-start method according to claim 1, characterized in that, The soft-start process is configured to run in four time periods; During the first working period, the duty cycle of the first switch, the second switch, the third switch, and the fourth switch is B1 and remains unchanged. During the second operating period, the duty cycle of the first switch, the second switch, the third switch, and the fourth switch is B2 and remains unchanged. During the third working period, the duty cycle of the first switch, the second switch, the third switch, and the fourth switch is B3 and remains unchanged. During the fourth working period, the duty cycles of the first switch, the second switch, the third switch, and the fourth switch gradually increase to the maximum value B4; B4>B3>B2>B1.

4. The soft-start method according to claim 1, characterized in that, The duty cycles of the first switch, the second switch, the third switch, and the fourth switch gradually increase during the kth working period; the increase in the duty cycles of the first switch, the second switch, the third switch, and the fourth switch during the (k+1)th working period is greater than the increase during the kth working period.

5. The soft-start method according to claim 4, characterized in that, The soft-start process is configured to run in three time periods; During the first working period, the duty cycle of the first switch, the second switch, the third switch, and the fourth switch gradually increases from 0 to C1; During the second working period, the duty cycle of the first switch, the second switch, the third switch, and the fourth switch gradually increases from C1 to C2; During the third working period, the duty cycle of the first switch, the second switch, the third switch, and the fourth switch gradually increases from C2 to the maximum value C3; C3>C2>C1.

6. The soft-start method according to claim 1, characterized in that, The N working periods are configured as a first stage and a second stage; in the first stage, the duty cycle of the first switch, the second switch, the third switch, and the fourth switch remains constant in each working period; in the second stage, the duty cycle of the first switch, the second switch, the third switch, and the fourth switch gradually increases in each working period.

7. The soft-start method according to claim 6, characterized in that, The soft-start method is configured to operate in three time periods; During the first working period, the duty cycle of the first switch, the second switch, the third switch, and the fourth switch is E1 and remains unchanged. During the second working period, the duty cycle of the first switch, the second switch, the third switch, and the fourth switch gradually increases from E1 to E2. During the third working period, the duty cycle of the first switch, the second switch, the third switch, and the fourth switch gradually increases from E2 to the maximum value E3. E3>E2>E1.

8. The soft-start method according to claim 1, characterized in that, The first and fourth switching transistors are turned on by a first driving signal, and the second and fourth switching transistors are turned on by a second driving signal; wherein the first driving signal and the second driving signal have the same frequency and are 180° out of phase.

9. A power conversion system, the power conversion system comprising a full-bridge resonant converter, characterized in that, The full-bridge resonant converter is configured to perform a soft-start using the soft-start method according to any one of claims 1-8.

10. A residential energy storage system, comprising a cloud platform, an energy management system, a power conversion system, and a battery management system, wherein the power conversion system includes a full-bridge resonant converter, characterized in that, The full-bridge resonant converter is configured to perform a soft-start using the soft-start method according to any one of claims 1-8.

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