Output status control method of high power charging module

Abstract

This invention discloses an output state control method for high-power charging modules, specifically relating to the field of power electronics technology. It involves collecting data from each high-power charging module connected in parallel to a common DC bus, including module output voltage, common DC bus voltage, output current direction, output contactor status, and active output commands. This identifies the target high-power charging module in the process of exiting or re-entering switching and calculates the residual voltage difference. Within the switching time window, a differential voltage current timing sequence is formed by sequentially associating these data. Based on the convergence characteristics of the reverse current with the residual voltage difference in the differential voltage current timing sequence, normal switching transition states and abnormal reverse current states are distinguished. For normal switching transition states, safe parallel connection is achieved by maintaining non-active output and connecting to a current-limiting and voltage-equalizing path. For abnormal reverse current states, fault isolation is achieved by disconnecting the output contactor and connecting to the output discharge path, and the status is re-acquired, thereby accurately distinguishing between switching transition states and fault states.

Description

Technical Field

[0001] This invention relates to the field of power electronics technology, and more specifically, to a method for controlling the output state of a high-power charging module. Background Technology

[0002] Currently, DC fast charging systems for new energy vehicles widely adopt multiple high-power charging modules connected in parallel to a common DC bus to achieve flexible configuration and dynamic adjustment of charging power.

[0003] In practical applications, multiple high-power charging modules are typically connected in parallel to provide high-power output. Power is dynamically adjusted by switching some modules in or out when the load changes or a module fails. Because a voltage difference usually exists between the output terminal of a module and the common DC bus when the module is disconnected or ready to be connected, this causes a short-term reverse charging current or circulating current to be generated on the bus through parasitic paths within the module. Existing output status control methods often rely solely on a single reverse current threshold, a fixed voltage threshold, or the opening / closing state of the output contactor for status judgment, neglecting the actual changes in the voltage difference between the bus and the module during the switching process. Summary of the Invention

[0004] In order to overcome the above-mentioned defects of the prior art, embodiments of the present invention provide an output state control method for a high-power charging module to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: The output state control method for a high-power charging module includes the following steps: S1. Collect the module output voltage, common DC bus voltage, output current direction, output contactor status and active output command of each high-power charging module connected in parallel to the common DC bus, and form a status sampling group; S2. Identify the target high-power charging module that is exiting or re-entering the switching based on the status sampling group, and calculate the residual voltage difference between the target high-power charging module and the common DC bus. S3. Within the time window of exiting or re-entering switching, the residual voltage difference, output current direction and output contactor status are associated in a timing sequence to form a differential voltage current timing sequence. S4. Determine whether the reverse current converges with the residual voltage difference based on the differential voltage current timing sequence. If it converges, mark it as a normal transition state; if it does not converge, mark it as an abnormal reverse current state. S5. When the mark is in the normal switching transition state, control the target high-power charging module to maintain non-active output and connect to the current limiting and voltage equalization path. After the residual voltage difference is not greater than the parallel allowable value, mark the parallel output state. S6. When the abnormal backflow status is marked, disconnect the output contactor of the target high-power charging module and connect the output discharge path. After discharge, return to S1.

[0006] In a preferred embodiment, S1 specifically refers to: The module output voltage and the common DC bus voltage of each high-power charging module connected in parallel to the common DC bus are acquired at the same acquisition time. The output current direction is determined by the flow from the high-power charging module to the common DC bus, and the output contactor status and active output command are read simultaneously. Based on the correspondence between each high-power charging module and the acquisition time, the module output voltage, common DC bus voltage, output current direction, output contactor status, and active output command are combined to form a status sampling group.

[0007] In a preferred embodiment, S2 specifically refers to: Compare the current state sampling group with the state sampling group of the adjacent previous sampling time according to the high-power charging module correspondence. When the active output command changes from enabling active output to disabling active output and the output contactor state changes from closed to open, the corresponding high-power charging module will be identified as the target high-power charging module that is exiting the switching process. When the active output command changes from prohibiting active output to allowing active output and the output contactor remains open, the corresponding high-power charging module will be identified as the target high-power charging module in the re-entry switching state. The residual voltage difference is the difference between the output voltage of the target high-power charging module and the voltage of the common DC bus.

[0008] In a preferred embodiment, S3 specifically refers to: The time window starts when the target high-power charging module is identified as being in the exit switching or re-entry switching state, and ends when the output contactor reaches the preset state corresponding to the exit switching or re-entry switching state. Within the time window of exiting or re-entering the switching, extract the residual voltage difference, output current direction, and output contactor status of the target high-power charging module according to the acquisition time. Based on the order of data acquisition, the residual voltage difference, output current direction, and output contactor status are combined accordingly, and the identification results of exiting or re-entering switching are retained to form a differential voltage current timing sequence.

[0009] In a preferred embodiment, S4 specifically refers to: The residual voltage difference, output current direction, and output contactor status are continuously read from the differential voltage current timing sequence at the acquisition time. When the output current flows from the common DC bus to the target high-power charging module, the corresponding acquisition time is recorded as the reverse current acquisition time. Based on the order of reverse current acquisition, determine whether the residual voltage difference decreases continuously, and determine whether the output current direction changes from flowing from the common DC bus to the target high-power charging module to flowing from the target high-power charging module to the common DC bus. If yes, mark it as a normal transition state; otherwise, mark it as an abnormal backflow state.

[0010] In a preferred embodiment, S5 specifically refers to: After marking the normal transition state, keep the active output command of the target high-power charging module in the "prohibit active output" state and connect it to the current limiting and voltage equalization path; The current-limiting and voltage-equalizing path is used to make the output voltage of the target high-power charging module change towards the common DC bus voltage, and the residual voltage difference and output current direction are continuously read according to the acquisition time. The residual voltage difference is updated according to the acquisition time. When the residual voltage difference is not greater than the parallel allowable value and the output current direction is not from the common DC bus to the target high-power charging module, the target high-power charging module is marked as allowing parallel output.

[0011] In a preferred embodiment, S6 specifically refers to: After marking the abnormal reverse feed status, keep the active output command of the target high-power charging module in the "disable active output" state and disconnect the output contactor of the target high-power charging module. After the output contactor is in the open state, connect the output discharge path and continue to read the residual voltage difference and output current direction according to the acquisition time. When the residual voltage difference is not greater than the allowable discharge value and the output current direction is not from the common DC bus to the target high-power charging module, the output discharge path and abnormal backflow status flag are removed, and S1 is returned to form a new status sampling group.

[0012] The technical effects and advantages of the output state control method for the high-power charging module of the present invention are as follows: By collecting module output voltage, common DC bus voltage, output current direction, output contactor status, and active output commands to form a state sampling group, each high-power charging module operating in parallel has a unified basis for judging its output status. The system identifies target high-power charging modules that are exiting or re-entering switching and calculates the residual voltage difference, enabling the control process to perform state analysis on the switching modules. Within a time window, the residual voltage difference, output current direction, and output contactor status are correlated to form a differential voltage-current timing sequence, allowing reverse current to be judged in conjunction with the residual voltage change process. By determining whether the reverse current converges with the residual voltage difference, the system can distinguish between normal switching transition states and abnormal reverse current states. In the normal switching transition state, controlled parallel conditions are confirmed through a current-limiting and voltage-equalizing path. In the abnormal reverse current state, state recovery is achieved through output contactor disconnection and output discharge path, thereby reducing module erroneous lockout, repeated switching, and unstable parallel output. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the output state control method of the high-power charging module of the present invention. Detailed Implementation

[0014] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0015] Example Figure 1 The present invention provides a method for controlling the output state of a high-power charging module, which includes the following steps: S1. Collect the module output voltage, common DC bus voltage, output current direction, output contactor status and active output command of each high-power charging module connected in parallel to the common DC bus, and form a status sampling group; S2. Identify the target high-power charging module that is exiting or re-entering the switching based on the status sampling group, and calculate the residual voltage difference between the target high-power charging module and the common DC bus. S3. Within the time window of exiting or re-entering switching, the residual voltage difference, output current direction and output contactor status are associated in a timing sequence to form a differential voltage current timing sequence. S4. Determine whether the reverse current converges with the residual voltage difference based on the differential voltage current timing sequence. If it converges, mark it as a normal transition state; if it does not converge, mark it as an abnormal reverse current state. S5. When the mark is in the normal switching transition state, control the target high-power charging module to maintain non-active output and connect to the current limiting and voltage equalization path. After the residual voltage difference is not greater than the parallel allowable value, mark the parallel output state. S6. When the abnormal backflow status is marked, disconnect the output contactor of the target high-power charging module and connect the output discharge path. After discharge, return to S1.

[0016] S1. Collect the module output voltage, common DC bus voltage, output current direction, output contactor status, and active output commands of each high-power charging module connected in parallel to the common DC bus, forming a status sampling group, including: The module output voltage and the common DC bus voltage of each high-power charging module connected in parallel to the common DC bus are acquired at the same acquisition time. Specifically, each high-power charging module is assigned a high-power charging module identifier, and a unified trigger signal is used as the starting reference for the acquisition time. This ensures that the module output voltage acquisition and the common DC bus voltage acquisition are completed within the allowable deviation of the same acquisition time. The allowable deviation of the same acquisition time is determined based on the maximum output voltage change rate and voltage sampling resolution of the high-power charging module. The determination method is to obtain the maximum unit time change of the module output voltage under the conditions of the fastest exit switching and the fastest re-entry switching allowed by the high-power charging module, and then select a time value that makes the voltage change within the allowable deviation of the same acquisition time less than the voltage sampling resolution. For example, the allowable deviation of the same acquisition time can be set to 100 microseconds.

[0017] The module output voltage is obtained through the isolation voltage sampling channel between the positive and negative output terminals of the high-power charging module. The common DC bus voltage is obtained through the isolation voltage sampling channel between the positive and negative terminals of the common DC bus. The module output voltage and the common DC bus voltage are processed to unify polarity before entering the state sampling group. The negative terminal of the common DC bus is used as the voltage reference terminal and the potential difference between the voltage reference terminal and the positive terminal is recorded as a positive value. If the original value obtained by the sampling channel has a reverse polarity mark, it is converted to a positive value according to the polarity relationship predetermined by the sampling channel.

[0018] Before acquiring the module output voltage and common DC bus voltage at the same acquisition time, zero-point correction and proportional correction are performed on the acquisition channels of each high-power charging module. Zero-point correction is performed by reading the original voltage value multiple times and calculating the average value as the zero-point offset under the condition that the high-power charging module is not connected to the common DC bus and there is no external voltage input at the output end. Proportional correction is performed by inputting a known DC voltage into the acquisition channel and calculating the proportional relationship between the known DC voltage and the original voltage value after deducting the zero-point offset to obtain the proportional correction value. The module output voltage and common DC bus voltage obtained at the acquisition time are formed by multiplying the original voltage value by the proportional correction value after deducting the zero-point offset.

[0019] The output current direction is determined by the flow from the high-power charging module to the common DC bus, and the output contactor status and active output command are read simultaneously. Specifically, the current sampling value is read in the output circuit of the high-power charging module, and the preset installation direction of the current sampling channel is read at the same time. When the preset installation direction of the current sampling channel is consistent with the direction of flow from the high-power charging module to the common DC bus, the current sampling value greater than zero is corresponding to the positive direction, and the current sampling value less than zero is corresponding to the flow from the common DC bus to the high-power charging module. When the preset installation direction of the current sampling channel is opposite to the direction of flow from the high-power charging module to the common DC bus, the current sampling value less than zero is corresponding to the positive direction, and the current sampling value greater than zero is corresponding to the flow from the common DC bus to the high-power charging module.

[0020] The output contactor state is obtained from the level state of the output contactor feedback contact. When the level state of the output contactor feedback contact remains stable within the allowable deviation at the same acquisition time, it is recorded as closed or open. When the level state of the output contactor feedback contact changes between adjacent acquisition times, it is recorded as the change process from closed to open or from open to closed. The active output command is read from the control flow of the high-power charging module and limited to allowing active output or disabling active output. The acquisition time for reading the active output command is the same as the acquisition time for reading the module output voltage, common DC bus voltage, output current direction, and output contactor state.

[0021] Based on the correspondence between each high-power charging module and the acquisition time, the module output voltage, common DC bus voltage, output current direction, output contactor status, and active output command are combined to form a status sampling group. Specifically, the high-power charging module identifier, acquisition time, module output voltage, common DC bus voltage, output current direction, output contactor status, and active output command are written into the same status record. The status records of all high-power charging modules at the same acquisition time are sorted according to the high-power charging module identifier to form a status sampling group.

[0022] A consistency check is performed on the state sampling group. The consistency check uses the high-power charging module identifier and the acquisition time as an index to confirm that the module output voltage, common DC bus voltage, output current direction, output contactor status, and active output command under the same high-power charging module identifier originate from the same acquisition time. It is confirmed that the common DC bus voltage is written to each high-power charging module identifier at the same acquisition time. It is confirmed that the output current direction is only one of the following: positive, flowing from the common DC bus to the high-power charging module, or zero current direction. It is confirmed that the output contactor status is only one of the following: closed, open, closed to open, or open to closed. It is confirmed that the active output command is only one of the following: active output allowed or active output prohibited.

[0023] S2. Identify the target high-power charging module that is exiting or re-entering the switching process based on the status sampling group, and calculate the residual voltage difference between the target high-power charging module and the common DC bus, including: Compare the current state sampling group with the state sampling group of the adjacent previous sampling time according to the high-power charging module correspondence. Specifically, state sampling groups are read in chronological order of acquisition time, and the latest state sampling group is determined as the state sampling group for the current acquisition time. State sampling groups prior to and adjacent to the current acquisition time are determined as the state sampling groups of adjacent previous acquisition times. If there is no state sampling group of adjacent previous acquisition times for the current acquisition time, only the state sampling group of the current acquisition time is saved, and the identification of target high-power charging modules in the exit or re-entry switching phase is not performed until a new state sampling group is formed in the next acquisition time, at which point comparison is performed. The determination of adjacent previous acquisition times is based on the order in which state sampling groups are saved; when there are abandoned state records during continuous acquisition, the state sampling group closest to the current acquisition time and passing the consistency check is taken as the state sampling group of adjacent previous acquisition times.

[0024] The system reads the high-power charging module identifier from each status record in the current acquisition time's status sampling group, and then searches for status records with the same high-power charging module identifier in adjacent previous acquisition time's status sampling groups. Two status records with the same high-power charging module identifier constitute a comparison object. In the comparison object, the status record at the current acquisition time provides the module output voltage, common DC bus voltage, output current direction, output contactor status, and active output command at the current acquisition time; the status record at an adjacent previous acquisition time provides the module output voltage, common DC bus voltage, output current direction, output contactor status, and active output command at the adjacent previous acquisition time. If a high-power charging module identifier exists in the current acquisition time's status sampling group, but the same high-power charging module identifier does not exist in the adjacent previous acquisition time's status sampling group, then the corresponding high-power charging module identifier will not participate in the exit handover identification and re-entry handover identification at the current acquisition time.

[0025] When the active output command changes from enabling active output to disabling active output and the output contactor state changes from closed to open, the corresponding high-power charging module will be identified as the target high-power charging module that is exiting the switching process. Specifically, the process for determining whether an active output command switches from allowing active output to disabling active output is as follows: Within the same comparison object, if the active output command at an adjacent previous acquisition time was allowing active output, and the active output command at the current acquisition time is disabling active output, then a switch from allowing active output to disabling active output is determined. The process for determining whether the output contactor state is in a closed-to-open transition is as follows: Within the same comparison object, if the output contactor state at an adjacent previous acquisition time was closed, and the output contactor state at the current acquisition time is in a closed-to-open transition or open, or if the output contactor state at an adjacent previous acquisition time was in a closed-to-open transition and the output contactor state at the current acquisition time is open, then a switch from allowing active output to disabling active output is determined. When an active output command switches from allowing active output to disabling active output and the output contactor state is in a closed-to-open transition, the high-power charging module corresponding to the comparison object is identified as the target high-power charging module exiting the switchover, and the exit switchover identification result is bound to the current acquisition time.

[0026] When the active output command changes from prohibiting active output to allowing active output and the output contactor remains open, the corresponding high-power charging module will be identified as the target high-power charging module in the re-entry switching state. Specifically, the process for determining whether an active output command changes from prohibiting active output to allowing active output is as follows: Within the same comparison object, if the active output command at an adjacent previous acquisition time was prohibiting active output, and the active output command at the current acquisition time is allowing active output, then a change from prohibiting to allowing active output is determined. The process for determining whether the output contactor remains open is as follows: Within the same comparison object, if the output contactor is open at an adjacent previous acquisition time and is also open at the current acquisition time, then the output contactor remains open. When an active output command changes from prohibiting to allowing active output and the output contactor remains open, the high-power charging module corresponding to the comparison object is identified as the target high-power charging module undergoing re-entry switching, and the re-entry switching identification result is bound to the current acquisition time.

[0027] If the same high-power charging module identifier meets both the exit switching identification condition and the re-entry switching identification condition at the current acquisition time, it will be uniquely processed according to the value of the active output command at the current acquisition time. If the active output command at the current acquisition time is set to prohibit active output, the identification result of exiting switching will be retained; if the active output command at the current acquisition time is set to allow active output, the identification result of re-entry switching will be retained. If the same high-power charging module identifier does not meet either the exit switching identification condition or the re-entry switching identification condition at the current acquisition time, the corresponding high-power charging module will not be identified as the target high-power charging module. After the uniqueness processing is completed, each target high-power charging module corresponds to only one of the identification results of exit switching or re-entry switching at the current acquisition time.

[0028] The residual voltage difference is the difference between the output voltage of the target high-power charging module and the voltage of the common DC bus. Specifically, the output voltage of the target high-power charging module is read from its status record at the current acquisition moment, and the common DC bus voltage is also read from the same status record. The residual voltage difference is obtained by subtracting the common DC bus voltage from the module output voltage. The residual voltage difference is signified: a positive residual voltage difference indicates that the output voltage of the target high-power charging module is higher than the common DC bus voltage; a negative residual voltage difference indicates that the output voltage of the target high-power charging module is lower than the common DC bus voltage; and a zero residual voltage difference indicates that the output voltage of the target high-power charging module is equal to the common DC bus voltage. The unit of the residual voltage difference is consistent with the units of the module output voltage and the common DC bus voltage, for example, volts.

[0029] S3. Within the time window for exiting or re-entering switching, the residual voltage difference, output current direction, and output contactor state are correlated in a timing sequence to form a differential voltage current timing sequence, including: The time window starts when the target high-power charging module is identified as being in the exit switching or re-entry switching state, and ends when the output contactor reaches the preset state corresponding to the exit switching or re-entry switching state. Specifically, the time window is established based on the identification results of exiting or re-entering the switch, which are already bound to the current acquisition time. The high-power charging module identifier corresponding to the target high-power charging module and the current acquisition time are read, and the current acquisition time when the target high-power charging module is identified as being in the exit or re-entry switch phase is determined as the starting point of the time window. The starting point of the time window is the identification time formed by comparing the state sampling group of the current acquisition time with the state sampling groups of adjacent previous acquisition times according to the high-power charging module correspondence. The starting point of the time window is maintained in correspondence with the high-power charging module identifier, the exit or re-entry switch identification result, the module output voltage, the common DC bus voltage, and the residual voltage difference of the target high-power charging module.

[0030] Based on the identification results of exit switching or re-entry switching, a preset state corresponding to the exit switching or re-entry switching is determined. The preset state corresponding to exit switching is that the output contactor state reaches open, because exit switching is formed by the active output command switching from enabling active output to disabling active output, accompanied by the output contactor state changing from closed to open. The preset state corresponding to re-entry switching is that the output contactor state changes from open to closed or closes, because re-entry switching is formed by the active output command switching from disabling active output to enabling active output, while the output contactor state remains open. The preset state is set based on the target change direction of the output contactor state relative to the start of the time window during exit switching or re-entry switching. The target change direction for exit switching is from closed to open, and the target change direction for re-entry switching is from open to closed.

[0031] Starting from the beginning of the time window, the status sampling groups that have passed the consistency check are read in chronological order of acquisition time. In each subsequent acquisition time's status sampling group, a status record matching the high-power charging module identifier of the target high-power charging module is searched. After finding a status record matching the target high-power charging module identifier, the output contactor status in that record is read and compared with the preset status corresponding to exiting or re-entering the switch. If the output contactor status corresponding to exiting the switch is open, the acquisition time at which this open state is reached is determined as the end of the time window; if the output contactor status corresponding to re-entering the switch is in a transition from open to closed or closed state, the acquisition time at which this transition is reached or closed state is determined as the end of the time window.

[0032] If, when continuing to read the state sampling group from the start of the time window, the output contactor state corresponding to the target high-power charging module has not reached the preset state corresponding to exiting or re-entering the switching within a certain number of sampling moments, then the start of the time window is retained and the state sampling group of subsequent sampling moments is read. If it is necessary to limit the continuous reading range, the continuous reading range is determined based on the allowable action time of the output contactor and the sampling period of the state sampling group. The determination method is to read the maximum action time of the output contactor of the target high-power charging module from closed to open or from open to closed under allowable operating conditions, and then add the maximum action time to a margin of not less than 2 sampling periods as the continuous reading range. For example, when the maximum action time is 80 milliseconds and the sampling period is 5 milliseconds, the continuous reading range is set to 90 milliseconds. If the preset state corresponding to exiting or re-entering the switching is not read within the continuous reading range, the already read state sampling group is retained, and the last sampling moment that passes the consistency check within the continuous reading range is taken as the temporary end point of the time window.

[0033] Within the time window of exiting or re-entering the switching, extract the residual voltage difference, output current direction, and output contactor status of the target high-power charging module according to the acquisition time. Specifically, at the start of the time window, the residual voltage difference is calculated by subtracting the common DC bus voltage from the output voltage of the target high-power charging module. At each subsequent acquisition point after the start of the time window, the residual voltage difference is calculated by reading the module output voltage and common DC bus voltage from the status record corresponding to the same high-power charging module identifier, and then subtracting the common DC bus voltage from the module output voltage. The residual voltage difference at each acquisition point within the time window retains its sign: a positive residual voltage difference indicates that the output voltage of the target high-power charging module is higher than the common DC bus voltage; a negative residual voltage difference indicates that the output voltage of the target high-power charging module is lower than the common DC bus voltage; and a zero residual voltage difference indicates that the output voltage of the target high-power charging module is equal to the common DC bus voltage.

[0034] During the time window for exiting or re-entering the switching process, the output current direction is read from the status record corresponding to the same high-power charging module identifier. The positive direction of the output current is defined as flowing from the high-power charging module to the common DC bus. The output current direction can only be one of the following: positive, flowing from the common DC bus to the high-power charging module, or zero current. The output contactor status is also read from the status record corresponding to the same high-power charging module identifier. The output contactor status can only be one of the following: closed, open, closed to open, or open to closed.

[0035] According to the order of acquisition time, the residual voltage difference, output current direction and output contactor status are combined accordingly, and the identification results of exiting switching or re-entering switching are retained to form a differential voltage current timing sequence. Specifically, using the high-power charging module identifier of the target high-power charging module as a fixed index and the acquisition time as a sequential index, the residual voltage difference, output current direction, and output contactor status corresponding to the same acquisition time are written into the same timing record. Each timing record also includes the identification result of exiting or re-entering the switching process, ensuring that each timing record formed within the time window reflects whether the corresponding acquisition time belongs to exiting or re-entering the switching process. The timing records are arranged from earliest to latest according to the acquisition time; the order of acquisition times cannot be changed, and the residual voltage difference, output current direction, and output contactor status under different high-power charging module identifiers cannot be written into the same timing record.

[0036] The differential voltage current timing sequence is formed by arranging all valid timing records from the start to the end of the time window according to their acquisition time sequence. The first timing record in the differential voltage current timing sequence corresponds to the start of the time window, and the last timing record corresponds to the end or temporary end of the time window. Each timing record in the differential voltage current timing sequence includes at least the high-power charging module identifier, acquisition time, identification result of exiting or re-entering switching, residual voltage difference, output current direction, and output contactor status. After the differential voltage current timing sequence is formed, it is bound to the high-power charging module identifier of the target high-power charging module.

[0037] S4. Determine whether the reverse current converges with the residual voltage difference based on the differential voltage current timing sequence. If convergence is achieved, mark the normal transition state; if convergence fails, mark the abnormal reverse current state, including: When determining whether the reverse current converges with the residual voltage difference based on the differential voltage current timing sequence, the differential voltage current timing sequence bound to the high-power charging module identifier of the target high-power charging module is used as input data. Each timing record is continuously read in chronological order from earliest to latest, and the high-power charging module identifier, acquisition time, identification result of exiting or re-entering the switching process, residual voltage difference, output current direction, and output contactor status are read from each timing record. If the differential voltage current timing sequence ends with a temporary end point of the time window, and the output contactor status corresponding to the temporary end point of the time window has not reached the preset state corresponding to exiting or re-entering the switching process, then normal switching judgment is not performed, and the corresponding target high-power charging module is directly marked as an abnormal reverse current state.

[0038] During the continuous reading of the differential voltage current timing sequence, when the output current flows from the common DC bus to the target high-power charging module, the corresponding acquisition time is recorded as the reverse current acquisition time, and the residual voltage difference and output contactor state at the corresponding acquisition time are bound and saved with the reverse current acquisition time. If the reverse current acquisition time corresponding to the exit switching identification result contains a change from open to closed output contactor state, the corresponding target high-power charging module is directly marked as an abnormal reverse current state; if the reverse current acquisition time corresponding to the re-entry switching identification result contains a change from closed to open output contactor state, the corresponding target high-power charging module is directly marked as an abnormal reverse current state. When the reverse current acquisition time set is empty, if the differential voltage current timing sequence has been read to the end of the time window or the temporary end of the time window, and the output contactor state reaches the preset state corresponding to the exit switching or re-entry switching, the corresponding target high-power charging module is marked as a normal switching transition state.

[0039] When determining whether the reverse current converges with the residual voltage difference based on the order of reverse current sampling times, the convergence criterion is the absolute value of the residual voltage difference at each reverse current sampling time. The absolute values ​​of the residual voltage difference at each sorted reverse current sampling time are read sequentially. If the absolute value of the residual voltage difference at the later sampling time is less than that at the earlier sampling time, the reduction condition is met; if the absolute value of the residual voltage difference at the later sampling time is equal to that at the earlier sampling time, it is considered to be at a constant level. The number of times the voltage difference remains constant is determined based on the voltage sampling resolution, the sampling period of the state sampling group, and the maximum allowable rate of change of the high-power charging module's output voltage. The determination method is to first obtain the voltage sampling resolution, then obtain the sampling period of the state sampling group and the maximum allowable rate of change of the high-power charging module's output voltage, and select the maximum number of consecutive constant levels that do not obscure the true decreasing trend of the residual voltage difference under the voltage sampling resolution constraint as the number of times the voltage difference remains constant is constant. If the absolute value of the residual voltage difference at any subsequent reverse current acquisition time is greater than the absolute value of the residual voltage difference at the previous reverse current acquisition time, or if the number of consecutive equalities is greater than the number of equalities tolerable, then the reverse current is determined not to converge with the residual voltage difference.

[0040] The method for determining the direction transition is as follows: taking the last reverse current acquisition moment as the starting point, continue reading the timing records after the last reverse current acquisition moment. If there is any timing record in which the output current direction is from the target high-power charging module to the common DC bus, then the output current direction is determined to have completed the transition from reverse to forward. If the output current direction in all timing records after the last reverse current acquisition moment is not from the target high-power charging module to the common DC bus, then the output current direction transition is determined to have not been completed. Only when the absolute value of the residual voltage difference corresponding to the reverse current acquisition moment satisfies a non-increasing trend and the output current direction has completed the transition from reverse to forward, is the corresponding target high-power charging module marked as a normal switching transition state; otherwise, the corresponding target high-power charging module is marked as an abnormal reverse current state. Normal switching transition states are bound and saved with the high-power charging module identifier, time window start point, time window end point or temporary time window end point, identification results of exiting or re-entering switching, the last reverse current acquisition time, the residual voltage difference corresponding to the last reverse current acquisition time, and the acquisition time when the direction conversion occurs; abnormal reverse charging states are bound with the high-power charging module identifier, time window start point, time window end point or temporary time window end point, identification results of exiting or re-entering switching, the acquisition time that caused the residual voltage difference not to decrease continuously or the last acquisition time that caused the direction conversion not to be completed, the residual voltage difference at the corresponding acquisition time, the output current direction, and the output contactor status.

[0041] S5. When the normal transition state is marked, the target high-power charging module is controlled to maintain non-active output and connected to the current-limiting and voltage-equalizing path. After the residual voltage difference is not greater than the parallel allowable value, the parallel output state is marked, including: The high-power charging module's positive output is connected to the common DC bus's positive terminal via an output contactor, while its negative output is directly connected to the common DC bus's negative terminal. The current-limiting and voltage-equalizing path includes a current-limiting device and a first controllable switch. The current-limiting device and the first controllable switch are connected in series and then in parallel across the output contactor, establishing a limited current path between the high-power charging module's output and the common DC bus when the output contactor is open. The output discharge path includes a discharge resistor and a second controllable switch. The discharge resistor and the second controllable switch are connected in series and then in parallel across the output contactor, establishing a controlled discharge path between the high-power charging module's output and the common DC bus when the output contactor is open. The first and second controllable switches are interlocked, preventing them from being simultaneously active at any given time.

[0042] When a normal switching transition state is marked, the system reads the high-power charging module identifier, time window start point, time window end point or temporary time window end point, identification result of exiting or re-entering switching, last reverse current acquisition time, residual voltage difference corresponding to the last reverse current acquisition time, acquisition time of direction conversion, and output current direction corresponding to the acquisition time of direction conversion. Based on the high-power charging module identifier, the system locates the target high-power charging module in the current acquisition time's state sampling group. After confirming that the target high-power charging module has been marked as a normal switching transition state and not as an abnormal reverse-feeding state, the system maintains the target high-power charging module's active output command as prohibited from active output. Before the target high-power charging module enters the parallel output allowed state, only the "prohibited active output" command is allowed to be written at each acquisition time; the "allowed active output" command is not allowed. If any acquisition time reads an active output command as allowed, the current limiting and voltage equalization path is disconnected, and the system returns to S1 to form a new state sampling group.

[0043] Before connecting the current-limiting and voltage-equalizing path, first confirm that the output discharge path is not connected, and then read the output contactor status of the target high-power charging module. If the normal switching transition state corresponds to the identification result of exiting the switching, the output contactor status of the target high-power charging module should be open; if the normal switching transition state corresponds to the identification result of re-engaging the switching, the output contactor status of the target high-power charging module should be open, a change from open to closed, or closed. After confirmation, close the first controllable switch to connect the current-limiting and voltage-equalizing path to both ends of the output contactor, establishing a limited current path between the output of the target high-power charging module and the common DC bus. The current-limiting value of the current-limiting and voltage-equalizing path is determined jointly based on the allowable parallel transient current of the target high-power charging module, the allowable pre-charge current of the output contactor, and the allowable transient current disturbance of the common DC bus. The determination method is to obtain the minimum value among the allowable parallel transient current of the target high-power charging module, the allowable pre-charge current of the output contactor, and the allowable transient current disturbance of the common DC bus, and use the minimum value as the upper limit of the current during the connection of the current-limiting and voltage-equalizing path.

[0044] After the current-limiting and voltage-equalizing path is connected, the module output voltage, common DC bus voltage, and output current direction of the target high-power charging module are continuously read according to the acquisition time, and the residual voltage difference is recalculated at each acquisition time. A voltage-equalizing tracking record is generated at each acquisition time, including the high-power charging module identifier, acquisition time, active output command, current-limiting and voltage-equalizing path connection status, module output voltage, common DC bus voltage, residual voltage difference, output current direction, and output contactor status. When updating the residual voltage difference according to the acquisition time, the module output voltage and common DC bus voltage at the latest acquisition time are used to recalculate the residual voltage difference, and the residual voltage difference at the latest acquisition time is used as the current residual voltage difference. Simultaneously, the residual voltage difference from the previous acquisition time is retained to determine the direction of change of the residual voltage difference during the voltage-equalizing process. If the absolute value of the current residual voltage difference is less than or equal to the absolute value of the residual voltage difference at the previous acquisition time, the current limiting and voltage equalization path will continue to be connected; if the absolute value of the current residual voltage difference is greater than the absolute value of the residual voltage difference at the previous acquisition time and the increase is greater than the voltage sampling resolution, the judgment of the allowed parallel output status will be stopped, and the corresponding target high-power charging module will be re-marked as an abnormal reverse feed state before proceeding to S6.

[0045] The parallel allowable value is used to determine whether the target high-power charging module has the voltage conditions to transition from the current-limiting and voltage-equalizing path to the parallel output state. The parallel allowable value is determined based on the allowable parallel inrush current of the target high-power charging module and the equivalent impedance between the output terminal of the target high-power charging module and the common DC bus. Under the condition that the target high-power charging module is prohibited from active output and the output contactor is in the open state, a known small current is applied through the current-limiting and voltage-equalizing path, and the voltage difference generated between the module output voltage of the target high-power charging module and the voltage of the common DC bus is read. Then, the equivalent impedance is obtained by the ratio between the voltage difference and the known small current. The product of the allowable parallel inrush current of the target high-power charging module and the equivalent impedance is taken as the upper limit of the parallel allowable value, and a value less than or equal to the upper limit of the parallel allowable value is selected as the parallel allowable value. When judging whether the residual voltage difference is not greater than the parallel allowable value, the judgment object of the residual voltage difference is the absolute value of the residual voltage difference; if the absolute value of the residual voltage difference at the current acquisition time is less than or equal to the parallel allowable value, and the output current direction is not from the common DC bus to the target high-power charging module, then the voltage condition and current direction condition for the allowable parallel output state are met.

[0046] If the current switching process is an exit switching, then when the absolute value of the residual voltage difference at the current acquisition time is less than or equal to the parallel allowable value and the output current direction is not from the common DC bus to the target high-power charging module, the target high-power charging module is marked as allowing parallel output, and the output contactor remains open, the current limiting and voltage equalization path is connected, and the active output command is disabled. If the current switching process is a re-entry switching, then when the absolute value of the residual voltage difference at the current acquisition time is less than or equal to the parallel allowable value and the output current direction is not from the common DC bus to the target high-power charging module, the active output command remains disabled, and the current limiting and voltage equalization path remains connected. If the output contactor state at the current acquisition time is open, a closing action is written to the output contactor; if the output contactor state at the current acquisition time is a change from open to closed, the output contactor state at subsequent acquisition times is read; if the output contactor state at the current acquisition time is closed, the closing action is not written again. The output contactor closure confirmation method involves maintaining the level of the output contactor feedback contact within the allowable deviation of the same acquisition time, and ensuring that the output contactor status is closed for at least two consecutive acquisition times. After the output contactor closes within the allowable operation time, the first controllable switch is disconnected, the current-limiting and voltage-equalizing path is exited, and the target high-power charging module is marked as allowing parallel output. If the output contactor fails to close within the allowable operation time, the allowing parallel output status is canceled, and the corresponding target high-power charging module is marked as abnormal reverse-feeding before proceeding to step S6. The allowing parallel output status is linked to the high-power charging module identifier, the allowable parallel output status acquisition time, the normal switching transition state, the residual voltage difference at the current acquisition time, the output current direction at the current acquisition time, the parallel allowable value, the output contactor status, and the current-limiting and voltage-equalizing path access status.

[0047] S6. When the abnormal backflow status is marked, disconnect the output contactor of the target high-power charging module and connect the output discharge path. After discharge, return to S1, including: When an abnormal backflow state is marked, the system reads the high-power charging module identifier, time window start point, time window end point or temporary time window end point, identification result of exiting or re-entering switching, the sampling moment that caused the residual voltage difference not to decrease continuously or the last sampling moment that caused the direction conversion not to be completed, the residual voltage difference at the corresponding sampling moment, the output current direction at the corresponding sampling moment, and the output contactor status at the corresponding sampling moment. Based on the high-power charging module identifier, the system locates the target high-power charging module in the newly formed state sampling group. After confirming that the target high-power charging module has been marked as an abnormal backflow state and has not been marked as a state where parallel output is allowed, the active output command of the target high-power charging module is kept as "prohibited from active output". Before the target high-power charging module is demarked as an abnormal backflow state, each sampling moment is only allowed to write "prohibited from active output" and not "prohibited from active output". If any sampling moment reads an active output command as "prohibited from active output", then "prohibited from active output" is rewritten and the abnormal backflow state processing procedure continues.

[0048] When the output contactor of the target high-power charging module is disconnected, the state of the output contactor at the current acquisition time is read. If the output contactor is closed, a disconnection action is written to the output contactor, and the output contactor state is continuously read at subsequent acquisition times. If the output contactor state changes from closed to open, the disconnection action is not repeated, and the output contactor state is read again. If the output contactor is open, a confirmation is performed before connecting the output discharge path. If the output contactor state changes from open to closed, a disconnection action is rewritten to the output contactor, and the output contactor state is read again. The output contactor disconnection confirmation method is that the level state of the output contactor feedback contact remains open within the allowable deviation at the same acquisition time, and the output contactor state is read as open for no less than two consecutive acquisition times. The allowable time for output contactor disconnection is determined based on the maximum operating time of the output contactor from closed to open within the rated control voltage and the allowable operating temperature range of the target high-power charging module, and is superimposed with the acquisition cycle of no less than two state sampling groups as a confirmation margin.

[0049] After the output contactor is in the open state, connect the output discharge path. Before connecting the output discharge path, confirm that the current limiting and voltage equalization path is not connected; if the current limiting and voltage equalization path is connected, first disconnect the first controllable switch, then close the second controllable switch, so that the output discharge path is connected to both ends of the output contactor. The output discharge path is used to make the module output voltage of the target high-power charging module approach the common DC bus voltage through the controlled discharge path when the target high-power charging module is kept prohibited from active output and the output contactor is in the open state. When the residual voltage difference is positive, the output terminal of the target high-power charging module releases charge to the common DC bus side through the discharge resistor; when the residual voltage difference is negative, the common DC bus side transfers charge to the output terminal of the target high-power charging module through the discharge resistor; when the residual voltage difference is zero, the output discharge path does not generate an equalization current driven by the residual voltage difference. The value of the bleeder resistor is determined based on the equivalent capacitance of the output terminal of the target high-power charging module, the initial absolute value of the residual voltage difference at the corresponding acquisition time in the abnormal reverse flow status mark, the allowable bleeder value, the allowable bleeder time, and the allowable power of the bleeder resistor. First, the nominal capacitance of the equivalent capacitance of the output terminal of the target high-power charging module is obtained. Then, the initial absolute value of the residual voltage difference at the corresponding acquisition time in the abnormal reverse flow status mark is read. Next, the amount of charge required for voltage equalization is determined based on the nominal capacitance of the equivalent capacitance of the output terminal of the target high-power charging module and the initial absolute value of the residual voltage difference. Finally, a bleeder resistor value is selected that can reduce the absolute value of the residual voltage difference to below the allowable bleeder value within the allowable bleeder time and ensure that the instantaneous power borne by the bleeder resistor at the moment of connection does not exceed the allowable power of the bleeder resistor.

[0050] After the output discharge path is connected, the module output voltage, common DC bus voltage, and output current direction of the target high-power charging module are continuously read according to the acquisition time, and the residual voltage difference is recalculated at each acquisition time. A discharge tracking record is generated at each acquisition time, which includes the high-power charging module identifier, acquisition time, output discharge path connection status, module output voltage, common DC bus voltage, residual voltage difference, output current direction, output contactor status, and active output command. When updating the residual voltage difference according to the acquisition time, the module output voltage and common DC bus voltage at the latest acquisition time are used to recalculate the residual voltage difference, and the residual voltage difference at the latest acquisition time is used as the current residual voltage difference. At the same time, the residual voltage difference at the previous acquisition time is retained to determine the direction of change of the residual voltage difference during the discharge process. If the absolute value of the current residual voltage difference is less than or equal to the absolute value of the residual voltage difference at the previous sampling time, the output discharge path will remain connected. If the absolute value of the current residual voltage difference is greater than the absolute value of the residual voltage difference at the previous sampling time and the increase is greater than the voltage sampling resolution, the active output command of the target high-power charging module will remain in the "prohibit active output" state. The output contactor status will be reconfirmed as open, and the output discharge path connection status will be reconfirmed as connected.

[0051] The discharge allowance value is used to determine whether the target high-power charging module has reached the voltage condition to remove the output discharge path and abnormal backflow status marker. The allowable discharge value is determined jointly based on the voltage sampling resolution, the allowable residual voltage range when the target high-power charging module re-enters the state sampling group, and the allowable voltage rebound range at the output of the target high-power charging module after the output discharge path is disconnected. The voltage sampling resolution, the upper limit of the allowable residual voltage range when the target high-power charging module re-enters the state sampling group, and the upper limit of the allowable voltage rebound range at the output of the target high-power charging module after the output discharge path is disconnected are obtained respectively. The upper limit of the allowable voltage rebound range at the output of the target high-power charging module after the output discharge path is disconnected is subtracted from the upper limit of the allowable residual voltage range when the target high-power charging module re-enters the state sampling group to obtain the candidate allowable discharge value. When the candidate allowable discharge value is not less than the voltage sampling resolution, the candidate allowable discharge value is used as the allowable discharge value. When the candidate allowable discharge value is less than the voltage sampling resolution, the allowable discharge time is extended or the upper limit of the allowable voltage rebound range at the output of the target high-power charging module after the output discharge path is disconnected is reduced until the candidate allowable discharge value is not less than the voltage sampling resolution. When determining that the residual voltage difference is not greater than the allowable discharge value, the judgment object of the residual voltage difference is the absolute value of the residual voltage difference. If the absolute value of the residual voltage difference at the current acquisition time is less than or equal to the allowable discharge value, the voltage release condition is met. If the absolute value of the residual voltage difference at the current acquisition time is greater than the allowable discharge value, the output terminal discharge path is kept connected and the discharge tracking record at the subsequent acquisition time is read. The allowable discharge time is determined based on the equivalent capacitance of the target high-power charging module output terminal, the resistance value of the discharge resistor, and the initial absolute value of the residual voltage difference at the corresponding acquisition time in the abnormal backflow status mark. The discharge duration that can reduce the absolute value of the residual voltage difference to below the allowable discharge value is selected, and the acquisition cycle of no less than 2 status sampling groups is superimposed as a confirmation margin.

[0052] When the output current direction is not from the common DC bus to the target high-power charging module, the output current direction can be positive or zero current. If the output current direction is from the common DC bus to the target high-power charging module, even if the absolute value of the residual voltage difference at the current acquisition time is less than or equal to the discharge allowable value, the output discharge path and abnormal backflow status flags will not be removed, and the residual voltage difference and output current direction at subsequent acquisition times will continue to be read. If the output current direction is positive or zero current, and the absolute value of the residual voltage difference at the current acquisition time is less than or equal to the discharge allowable value, then the target high-power charging module simultaneously meets the voltage release condition and the current direction release condition. If the duration of the output discharge path connection reaches the discharge allowable time and the absolute value of the residual voltage difference at the current acquisition time is still greater than the discharge allowable value, then the abnormal backflow status flag will not be removed, and the active output command of the target high-power charging module will remain set to prohibit active output.

[0053] If the absolute value of the residual voltage difference at the current acquisition moment is less than or equal to the allowable discharge value, and the output current direction is not from the common DC bus to the target high-power charging module, first disconnect the second controllable switch, and then read the output discharge path connection status at subsequent acquisition moments to confirm that the output discharge path connection status is not connected. After confirming that the output discharge path connection status is not connected, remove the abnormal backflow status flag. When removing the abnormal backflow status flag, bind and save the high-power charging module identifier, the acquisition moment when the abnormal backflow status is removed, the residual voltage difference at the last acquisition moment before removal, the output current direction at the last acquisition moment before removal, the allowable discharge value, the output discharge path connection status, and the output contactor status. After removing the abnormal backflow status flag, do not write "allow active output", and keep the active output command of the target high-power charging module "disable active output".

[0054] After removing the output discharge path and abnormal backflow status flag, the system returns to S1 to form a new status sampling group. Upon returning to S1, the module output voltage and common DC bus voltage of each high-power charging module connected in parallel to the common DC bus are reacquired at the same acquisition time. The output current direction is determined again with the flow from the high-power charging module to the common DC bus as the positive direction. The output contactor status and active output command are re-read synchronously, and a new status sampling group is formed according to the correspondence between each high-power charging module and the acquisition time. The new status sampling group does not use the previously removed abnormal backflow status flag, but only retains the high-power charging module identifier, acquisition time, module output voltage, common DC bus voltage, output current direction, output contactor status, and active output command, enabling the target high-power charging module to participate again in the exit or re-entry switching identification.

[0055] The above embodiments are only used to illustrate the technical methods of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical methods of the present invention without departing from the spirit and scope of the technical methods of the present invention.

Claims

1. A method for controlling the output state of a high-power charging module, characterized in that, Includes the following steps: S1. Collect the module output voltage, common DC bus voltage, output current direction, output contactor status and active output command of each high-power charging module connected in parallel to the common DC bus, and form a status sampling group; S2. Identify the target high-power charging module that is exiting or re-entering the switching based on the status sampling group, and calculate the residual voltage difference between the target high-power charging module and the common DC bus. S3. Within the time window of exiting or re-entering switching, the residual voltage difference, output current direction and output contactor status are associated in a timing sequence to form a differential voltage current timing sequence. S4. Determine whether the reverse current converges with the residual voltage difference based on the differential voltage current timing sequence. If it converges, mark it as a normal transition state; if it does not converge, mark it as an abnormal reverse current state. S5. When the mark is in the normal switching transition state, control the target high-power charging module to maintain non-active output and connect to the current limiting and voltage equalization path. After the residual voltage difference is not greater than the parallel allowable value, mark the parallel output state. S6. When the abnormal backflow status is marked, disconnect the output contactor of the target high-power charging module and connect the output discharge path. After discharge, return to S1.

2. The output state control method for a high-power charging module according to claim 1, characterized in that, S1, specifically: The module output voltage and the common DC bus voltage of each high-power charging module connected in parallel to the common DC bus are acquired at the same acquisition time. The output current direction is determined by the flow from the high-power charging module to the common DC bus, and the output contactor status and active output command are read simultaneously. Based on the correspondence between each high-power charging module and the acquisition time, the module output voltage, common DC bus voltage, output current direction, output contactor status, and active output command are combined to form a status sampling group.

3. The output state control method for a high-power charging module according to claim 2, characterized in that, S2, specifically: Compare the current state sampling group with the state sampling group of the adjacent previous sampling time according to the high-power charging module correspondence. When the active output command changes from enabling active output to disabling active output and the output contactor state changes from closed to open, the corresponding high-power charging module will be identified as the target high-power charging module that is exiting the switching process. When the active output command changes from prohibiting active output to allowing active output and the output contactor remains open, the corresponding high-power charging module will be identified as the target high-power charging module in the re-entry switching state. The residual voltage difference is the difference between the output voltage of the target high-power charging module and the voltage of the common DC bus.

4. The output state control method for a high-power charging module according to claim 3, characterized in that, S3, specifically: The time window starts when the target high-power charging module is identified as being in the exit switching or re-entry switching state, and ends when the output contactor reaches the preset state corresponding to the exit switching or re-entry switching state. Within the time window of exiting or re-entering the switching, extract the residual voltage difference, output current direction, and output contactor status of the target high-power charging module according to the acquisition time. Based on the order of data acquisition, the residual voltage difference, output current direction, and output contactor status are combined accordingly, and the identification results of exiting or re-entering switching are retained to form a differential voltage current timing sequence.

5. The output state control method for a high-power charging module according to claim 4, characterized in that, S4, specifically: The residual voltage difference, output current direction, and output contactor status are continuously read from the differential voltage current timing sequence at the acquisition time. When the output current flows from the common DC bus to the target high-power charging module, the corresponding acquisition time is recorded as the reverse current acquisition time. Based on the order of reverse current acquisition, determine whether the residual voltage difference decreases continuously, and determine whether the output current direction changes from flowing from the common DC bus to the target high-power charging module to flowing from the target high-power charging module to the common DC bus. If yes, mark it as a normal transition state; otherwise, mark it as an abnormal backflow state.

6. The output state control method for a high-power charging module according to claim 5, characterized in that, S5, specifically: After marking the normal transition state, keep the active output command of the target high-power charging module in the "prohibit active output" state and connect it to the current limiting and voltage equalization path; The current-limiting and voltage-equalizing path is used to make the output voltage of the target high-power charging module change towards the common DC bus voltage, and the residual voltage difference and output current direction are continuously read according to the acquisition time. The residual voltage difference is updated according to the acquisition time. When the residual voltage difference is not greater than the parallel allowable value and the output current direction is not from the common DC bus to the target high-power charging module, the target high-power charging module is marked as allowing parallel output.

7. The output state control method for a high-power charging module according to claim 6, characterized in that, S6, specifically: After marking the abnormal reverse feed status, keep the active output command of the target high-power charging module in the "disable active output" state and disconnect the output contactor of the target high-power charging module. After the output contactor is in the open state, connect the output discharge path and continue to read the residual voltage difference and output current direction according to the acquisition time. When the residual voltage difference is not greater than the allowable discharge value and the output current direction is not from the common DC bus to the target high-power charging module, the output discharge path and abnormal backflow status flag are removed, and S1 is returned to form a new status sampling group.

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