Sst control method and system with battery replacement bypass latching and five-phase load recovery

Abstract

The present application provides an SST control method and system with battery replacement bypass locking and five-phase load recovery, and relates to the technical field of power supply control. The method performs bypass capacity checking according to load power, expected battery replacement time window, and available power and energy of the bypass power supply; after the checking, the bypass is locked, and a battery replacement permission is generated after the bypass is stable and the battery branch to be replaced is isolated; after the battery to be replaced is connected, the SST power unit is grouped and put into operation, and the five-phase load is recovered in stages according to the bus voltage, current imbalance, unit temperature, and battery power margin; and after the load is stable, the power is transferred and the bypass is exited. The present application can reduce the risk of bus voltage loss, connection impact, and concentrated recovery, and improve the power supply continuity and battery replacement safety.

Description

Technical Field

[0001] This invention relates to the field of power supply control technology, and in particular to an SST control method and system with power swapping bypass latching and five-phase load recovery. Background Technology

[0002] With the development of battery swapping energy storage stations, mobile power supply platforms, and power supply systems for special vehicles, battery swapping control has gradually shifted from simple mechanical disassembly and assembly to coordinated control of electrical safety access and continuous power supply. Chinese patent application CN114274831A discloses a battery swapping assembly and its control method, a battery swapping vehicle, and a battery swapping system. This method limits the inrush current when the battery is connected via a pre-charging branch and closes the main contactor after the voltage difference between the battery and the load circuit meets certain conditions, thus achieving safe access for the swapped battery. This scheme promotes the evolution of the battery swapping process from direct access to pre-charging access, but it mainly focuses on the circuit structure of the battery swapping assembly and pre-charging control, without addressing the prediction of the continuous power supply capacity of the bypass power supply during battery swapping or the interlocking of mechanical battery swapping permission and electrical isolation status.

[0003] Furthermore, Chinese patent application CN120300653A discloses a solid-state transformer (SST) grid-connected operation and maintenance circuit and method, controller, and storage medium. It achieves uninterrupted power supply (UPS) operation and maintenance through power transmission bypass channels, power module isolation, and shock-free recovery, enabling SST control to evolve from downtime maintenance to continuous operation supported by bypass. However, in battery mechanical swapping scenarios, it is still necessary to address the joint verification of available bypass power, available energy, and swapping time window; the current reduction isolation of the battery branch to be swapped out; the verification and pre-charging of the battery to be swapped in; and the orderly recovery of the SST power unit and five-phase load. Existing technologies have not yet formed a unified closed-loop control scheme covering the above processes and possessing over-limit pause, rollback, and bypass latch-out functions.

[0004] In view of this, there is an urgent need for an SST control method and system with battery swapping bypass latch and five-phase load recovery to at least solve the above-mentioned deficiencies. Summary of the Invention

[0005] One of the objectives of this invention is to provide an SST control method and system with battery swapping bypass latch and five-phase load recovery to solve the problems mentioned in the background art.

[0006] The SST control method with battery swapping bypass latching and five-phase load recovery provided in this embodiment of the invention is applied to a battery swapping power supply system including a DC bus, bypass power supply, bypass switch, battery branch to be swapped out, battery branch to be swapped in, mechanical battery swapping mechanism, multiple SST power units, five-phase load, main contactor for battery to be swapped out, main contactor for battery to be swapped in, and pre-charge branch. The method includes: Obtain the power of the load to be supplied, the available power and energy of the bypass power supply, and verify the bypass capability based on the power of the load to be supplied, the expected battery swapping time window, and the available power and energy of the bypass power supply. When the bypass capability verification is passed, the bypass latch flag is set, which increases the output power of the bypass power supply and decreases the output power of the battery branch to be replaced. When the bypass stability condition is met and the battery branch to be replaced is electrically isolated, a mechanical battery swapping permit is generated. After the mechanical battery swap is completed, the battery to be swapped in is connected, the load demand power and the allowable output power of the battery to be swapped in are obtained, and the SST power unit is grouped and put into operation according to the load demand power, the available power of the SST power unit and the allowable output power of the battery to be swapped in. The five-phase load is restored one phase at a time according to the five-phase load restoration order. The DC bus voltage margin, five-phase current imbalance, SST power unit temperature margin, and battery power margin to be replaced are used as four recovery parameters to determine the load recovery status. When the load recovery status is normal, the current recovery phase is recovered according to the first recovery slope. When the load recovery status is warning, the current recovery phase is recovered according to the second recovery slope, which is less than the first recovery slope, and the release of the next recovery phase is paused. When the load recovery status is severely over-limit, the most recent recovery phase is rolled back to the previous stable reference value. The status update process is performed based on the four recovery parameters reacquired after control. After the five-phase load stabilizes, the load power is transferred from the bypass power supply to the activated SST power unit, and the bypass switch is disconnected and the bypass latch flag is reset when the bypass exit condition is met.

[0007] Preferably, the bypass capability verification includes: The estimated battery swapping time window is determined based on the pre-set mechanical battery swapping time, communication confirmation time, and time margin. The bypass demand power is determined based on the power of the load to be supplied and the preset conversion loss, and the bypass energy demand is determined based on the bypass demand power and the expected battery swapping time window. When the available power of the bypass power supply is not less than the bypass required power, and the available energy of the bypass power supply is not less than the bypass required energy, the bypass capability verification is deemed to have passed. If at least one condition is not met, the pre-configured non-critical load is removed and the bypass capability is re-verified; if the re-verification of the bypass capability fails, the mechanical battery swapping permit is rejected and the branch of the battery to be swapped out is kept powered.

[0008] Preferably, the setting of the bypass latch flag and the generation of mechanical battery swapping permission include: When the bypass capability verification is passed, the output power reference value of the bypass power supply is increased according to the restricted slope, and the output power reference value of the battery branch to be replaced is decreased according to the power balance relationship. The bypass stability condition is defined as the time during which the DC bus voltage deviation, DC bus voltage change rate, and bypass power supply load rate are all within their respective stable ranges and remain stable. After the bypass stability condition is met and the output power of the battery branch to be replaced is reduced to the isolation power range, the drive of the SST power unit corresponding to the battery branch to be replaced is stopped, and the main contactor of the battery to be replaced connected to the battery branch to be replaced is disconnected. The conditions for mechanical battery swapping interlocking are: the current of the battery branch to be swapped is lower than the isolation current threshold, the main contactor of the battery to be swapped is disconnected, the residual voltage of the battery branch to be swapped is lower than the safe residual voltage threshold, and the mechanical battery swapping mechanism is ready. A mechanical battery swapping permit is generated when the mechanical battery swapping interlocking conditions are met; if any condition in the mechanical battery swapping interlocking conditions fails, the mechanical battery swapping permit is revoked while the bypass latching flag is maintained.

[0009] Preferably, the battery to be replaced is connected to the following: After the battery to be replaced in the battery branch is installed and mechanically locked, the identity information, rated parameters, connection polarity and insulation status of the battery to be replaced are verified to obtain the access verification result. When the access verification result is passed, and the voltage, temperature and state of charge of the battery to be replaced are within the corresponding allowable range, the battery to be replaced is precharged through the precharge branch, and the precharge voltage difference between the battery to be replaced and the DC bus and the precharge current flowing through the precharge branch are obtained. When the pre-charge differential voltage is lower than the differential voltage threshold and the pre-charge current is lower than the pre-charge termination current threshold, and the pre-charge confirmation time continues, the main contactor of the battery to be replaced connecting the battery to be replaced and the SST power unit is closed, and the pre-charge branch is disconnected. When the access verification result is unsuccessful or the pre-charging is incomplete, the main contactor of the battery to be replaced must not be closed and the bypass latching flag must be maintained.

[0010] Preferably, the determination of the SST power unit grouping and the five-phase load restoration sequence includes: Obtain the current output power of the bypass power supply, determine the difference between the load demand power and the current output power as the SST to be undertaken power, and determine the number of power units to be put into operation based on the SST to be undertaken power and the available power of each SST power unit after temperature derating and voltage derating. Multiple SST power units are divided into multiple power unit groups. First, the smallest power unit group, determined by the number of power units to be put into operation and capable of meeting the power of the load to be supplied, is put into operation according to the principle of having the fewest power units. After the smallest power unit group completes soft start, the DC side current stabilizes and the temperature does not exceed the limit, the subsequent power unit groups are put into operation in sequence until the total available power of the put-in SST power units is not less than the power to be supplied by the SST. The recovery order of the five-phase load is determined based on the recovery priority, starting impact parameters, and interphase coupling parameters of each phase load. The power reference value or current reference value of the corresponding load is increased phase by phase according to the recovery order of the five-phase load.

[0011] Preferably, the four recovery parameters and load recovery status are determined as follows: The DC bus allowable voltage range is preset, and the difference between the DC bus voltage and the nearest boundary value in the DC bus allowable voltage range is determined as the DC bus voltage margin. Calculate the average current of the five phases of the five-phase load, and determine the unbalance of the five-phase current based on the deviation of each phase current from the average current of the five phases. Obtain the allowable temperature of the SST power unit, and determine the difference between the allowable temperature of the SST power unit and the highest temperature among all SST power unit temperatures as the SST power unit temperature margin. Obtain the current output power of the branch of the battery to be replaced, and determine the difference between the allowable output power of the battery to be replaced and the current output power as the power margin of the battery to be replaced. Set warning thresholds and severe over-limit thresholds for the four recovery parameters respectively. Compare the four recovery parameters with the corresponding warning thresholds and severe over-limit thresholds to obtain the recovery parameter status level for each recovery parameter. Based on the recovery parameter status level with the highest risk, determine the load recovery status as normal status, warning status, or severe over-limit status.

[0012] Preferably, the first recovery slope and the second recovery slope are determined as follows: The direction of parameter change is determined based on the difference between the four recovery parameters of the current control cycle and the four recovery parameters of the previous control cycle. Among them, the direction of increased risk is the decrease in DC bus voltage margin, the increase in five-phase current imbalance, the decrease in SST power unit temperature margin, and the decrease in the power margin of the battery to be replaced. Based on the distance between the four recovery parameters and the corresponding early warning thresholds and severe over-limit thresholds, as well as the direction of parameter change, the risk characterization value corresponding to each recovery parameter is determined, and the slope limit level is determined based on the risk characterization value with the highest risk level. Based on the pre-set base recovery slope, when the slope limit level is normal, a first recovery slope is generated based on the base recovery slope; when the slope limit level is warning level, the base recovery slope is decayed based on the risk characterization value with the highest risk level to generate a second recovery slope; when the slope limit level is severe over-limit level, a load phase rollback command is generated to roll back the most recently recovered phase to the previous stable reference value. Based on the preset slope change limit of adjacent control cycles and the remaining available power of the SST power units that have been put into operation, the first recovery slope or the second recovery slope is limited.

[0013] Preferably, the state update process includes: After changing the power reference value or current reference value of the current recovery phase, the four recovery parameters are reacquired after the operation parameter response confirmation time. The four newly acquired recovery parameters are compared with the four recovery parameters before the power reference value or current reference value of the current recovery phase was changed, so as to obtain the trend of the recovery parameter change corresponding to each recovery parameter. When the DC bus voltage margin, SST power unit temperature margin, or battery power margin to be replaced increases, or the five-phase current imbalance decreases, the corresponding recovery parameter change trend is determined to be a change towards safety; when the change direction is opposite, the corresponding recovery parameter change trend is determined to be a change towards risk. When all recovery parameters change in a safe direction or remain stable, continue to restore the current recovery phase, and release the next recovery phase after the current recovery phase stabilizes; when at least one recovery parameter changes in a risk direction for a preset number of control cycles, maintain the power reference value or current reference value of the current recovery phase; when at least one recovery parameter reaches the corresponding severe over-limit threshold, revert the most recent recovery phase to the previous stable reference value. The load recovery status for the next control cycle is determined based on the four reacquired recovery parameters.

[0014] Preferably, the bypass exit condition and the reset of the bypass latch flag include: After the bypass latch flag is set, maintain the power supply connection between the bypass power supply and the DC bus; After the five-phase load stabilizes, the output power of the SST power units that have been put into operation is increased and the output power of the bypass power supply is reduced according to the power complementarity relationship. The following conditions are defined as bypass exit conditions: the absolute value of the output power of the bypass power supply is lower than the zero power threshold, the parallel circulating current between the bypass power supply and the SST power unit that has been put into operation is lower than the circulating current threshold, there is no reverse power transmitted from the DC bus to the bypass power supply, and the voltage deviation and voltage change rate of the DC bus are both within the corresponding stable range and continue to exit the confirmation time. When the bypass exit condition is met, the bypass switch is disconnected and the bypass latch flag is reset; The bypass latch flag must not be reset when the battery to be replaced is not connected, the SST power unit grouping is not completed, the load recovery status is in a severely over-limit state, or the bypass exit condition is not met.

[0015] The SST control system with battery swapping bypass latch and five-phase load recovery provided in this embodiment of the invention is used to execute any of the above-mentioned SST control methods with battery swapping bypass latch and five-phase load recovery. It includes a controller, a DC bus, a bypass power supply, a bypass switch, a battery branch to be swapped out, a battery branch to be swapped in, a mechanical battery swapping mechanism, multiple SST power units, a five-phase load, a main contactor for the battery to be swapped out, a main contactor for the battery to be swapped in, a pre-charge branch, and a sampling unit. The bypass power supply is connected to the DC bus through a bypass switch. The battery branch to be replaced is connected to the corresponding SST power unit through the main contactor of the battery to be replaced. The battery branch to be replaced is connected to the corresponding SST power unit through the main contactor of the battery to be replaced. The battery branch to be replaced is also connected to the DC bus through a precharge branch. The SST power unit is connected to the DC bus. The five-phase load is powered by the DC bus. The sampling unit is connected to the controller. The sampling unit is used to collect the voltage of the DC bus, the phase current of each phase of the five-phase load, the temperature of the SST power unit, the output power of the bypass power supply, the output power of the battery branch to be replaced, and the voltage, temperature and state of charge of the battery to be replaced in the battery branch. The controller is used to obtain the power of the load to be supplied and the available power and energy of the bypass power supply. Based on the power of the load to be supplied, the expected battery swapping time window, and the available power and energy of the bypass power supply, the bypass capability is checked. When the bypass capability check is passed, the bypass latch flag is set. When the bypass stability condition is met and the battery branch to be swapped out is electrically isolated, the mechanical battery swapping permission is output to the mechanical battery swapping mechanism. The controller is also used to group and activate the SST power units according to the load demand power, the available power of the SST power unit and the allowable output power of the battery to be replaced after the battery is connected, and restore the five-phase load phase by phase according to the five-phase load restoration order. The controller is also used to determine the load recovery status based on the DC bus voltage margin, five-phase current imbalance, SST power unit temperature margin and the power margin of the battery to be replaced, and to control the current recovery phase to continue to recover, reduce the recovery slope or fall back to the previous stable reference value according to the load recovery status. The controller is also used to transfer the load power from the bypass power supply to the activated SST power unit after the five-phase load has stabilized, and to disconnect the bypass switch and reset the bypass latch flag when the bypass exit condition is met.

[0016] The beneficial effects of this invention are as follows: This invention jointly verifies the available power, available energy, and expected battery swapping time window of the bypass power supply before battery swapping to avoid insufficient bypass maintenance time; it improves the safety of mechanical battery swapping through bypass latching and bypass stabilization, battery branch isolation, contactor status, residual voltage, and mechanical readiness interlocking; it reduces access impact, bus fluctuation, current imbalance, and module thermal stress through battery verification and pre-charging, SST power unit grouping and activation, and five-phase load graded slope recovery; it enhances anomaly handling capabilities through parameter status updates and over-limit rollback, and achieves smooth bypass exit by utilizing power complementary transfer, circulating current, and reverse power determination, thereby improving the power supply continuity and control stability throughout the battery swapping process.

[0017] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in this application.

[0018] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0019] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the overall flow of the SST control method with battery swapping bypass latch and five-phase load recovery in an embodiment of the present invention; Figure 2 This is a block diagram of the SST control system with battery swapping bypass latch and five-phase load recovery in an embodiment of the present invention. Figure 3 This is a schematic diagram of the unified control state machine and abnormal rollback relationship in an embodiment of the present invention. Detailed Implementation

[0020] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0021] Example 1: This example provides an SST control method with battery swapping bypass latching and five-phase load recovery, such as... Figure 1 As shown, the battery swapping power supply system includes a DC bus, bypass power supply, bypass switch, battery branch to be swapped out, battery branch to be swapped in, mechanical battery swapping mechanism, multiple SST power units, five-phase load, main contactor for battery to be swapped out, main contactor for battery to be swapped in, and pre-charge branch, comprising: Obtain the power of the load to be supplied, the available power and energy of the bypass power supply, and verify the bypass capability based on the power of the load to be supplied, the expected battery swapping time window, and the available power and energy of the bypass power supply. When the bypass capability verification is passed, the bypass latch flag is set, which increases the output power of the bypass power supply and decreases the output power of the battery branch to be replaced. When the bypass stability condition is met and the battery branch to be replaced is electrically isolated, a mechanical battery swapping permit is generated. After the mechanical battery swap is completed, the battery to be swapped in is connected, the load demand power and the allowable output power of the battery to be swapped in are obtained, and the SST power unit is grouped and put into operation according to the load demand power, the available power of the SST power unit and the allowable output power of the battery to be swapped in. The five-phase load is restored one phase at a time according to the five-phase load restoration order. The DC bus voltage margin, five-phase current imbalance, SST power unit temperature margin, and battery power margin to be replaced are used as four recovery parameters to determine the load recovery status. When the load recovery status is normal, the current recovery phase is recovered according to the first recovery slope. When the load recovery status is warning, the current recovery phase is recovered according to the second recovery slope, which is less than the first recovery slope, and the release of the next recovery phase is paused. When the load recovery status is severely over-limit, the most recent recovery phase is rolled back to the previous stable reference value. The status update process is performed based on the four recovery parameters reacquired after control. After the five-phase load stabilizes, the load power is transferred from the bypass power supply to the activated SST power unit, and the bypass switch is disconnected and the bypass latch flag is reset when the bypass exit condition is met.

[0022] In this embodiment, the bypass latch flag is a logic state bit maintained by the unified state machine controller. When set, the bypass switch enters a holding state, and this flag can only be released by the unified state machine through an explicit reset command when the bypass is out of state. It is not automatically released due to short-term recovery of bus voltage, momentary communication interruption, or local controller reset. This differs from the usual bypass control logic and aims to prevent any accidental event during the power swapping process from causing the bypass to be accidentally disconnected and resulting in bus voltage loss.

[0023] In this embodiment, a five-phase load refers to a five-phase output load driven by a DC bus through five independent conversion channels A, B, C, D, and E. Each phase is configured with an independent current sampling and controlled power / current reference value output channel. There may be start-up impact and inter-phase coupling relationship between the five phases. Therefore, all phases cannot be put into operation at the same time. They need to be restored one phase at a time according to the restoration order.

[0024] In this embodiment, the currently recovering phase refers to the phase that is currently performing a power reference value or current reference value increase operation within the current control cycle; the most recently recovered phase refers to the last phase that has started increasing the power reference value or current reference value in the current five-phase load recovery sequence. Both refer to the same phase during single-phase recovery; when multi-phase parallel recovery is allowed, the most recently recovered phase refers to the last phase to start, while the currently recovering phase may include multiple phases recovering in parallel. When a severe over-limit condition requires rollback, the most recently recovered phase is rolled back instead of all recovered phases to alleviate system stress at minimal cost.

[0025] In this embodiment, the power of the load to be supplied is calculated in real time by the EMS based on the current critical load list of the system. The available power and available energy of the bypass power supply are reported by the bypass power supply management unit through the communication interface. The controller reads the latest value from the above interface after the battery swapping request is triggered.

[0026] The working principle and beneficial effects of the above technical solution: This embodiment organizes the entire battery swapping process into a unified state machine with anomaly rollback capability, realizing end-to-end closed-loop control of "battery swapping request—bypass capacity prediction—bypass latching and voltage regulation—current reduction and isolation of the battery branch to be swapped out—mechanical battery swapping permission—verification and pre-charging of the battery to be swapped in—grouping and activation of SST power units—limited recovery of five-phase load slope—smooth bypass exit." By simultaneously verifying the available power and energy of the bypass before mechanical battery swapping, bus voltage loss caused by insufficient maintenance time despite apparent bypass capacity is avoided; by interlocking bypass latching with battery swapping, mechanical action is strictly delayed after the establishment of bypass steady state and electrical isolation of the battery branch to be swapped out; by adaptively limiting the recovery slope of the five-phase load online through four recovery parameters, bus impact and module overheating caused by concentrated recovery are reduced; by the power complementary slope between the bypass and the activated SST power units, low circulating current and no reverse power bypass exit are achieved, comprehensively improving the safety, continuity, and recoverability of the battery swapping process.

[0027] Example 2: Based on Example 1, the bypass capability verification includes: The estimated battery swapping time window is determined based on the pre-set mechanical battery swapping time, communication confirmation time, and time margin. Based on the preset mechanical battery swapping time Communication confirmation time and time leeway Determine the expected battery swapping time window Its calculation satisfies: Then, a dual constraint check of instantaneous power and energy is performed: assuming the available power of the bypass power supply is... The power of the critical load to be supplied is The conversion loss of a solid-state transformer is The configured power safety margin is Then the instantaneous power should satisfy: Assume the current available energy of the bypass power supply is Then the energy constraint should satisfy: When both the instantaneous power inequality and the energy constraint inequality conditions mentioned above are satisfied, it means that the bypass capability verification has passed. If at least one condition is not met, the pre-configured non-critical load is removed and the bypass capability is re-verified; if the re-verification of the bypass capability fails, the mechanical battery swapping permit is rejected and the branch of the battery to be swapped out is kept powered.

[0028] The expected battery swapping time window is the sum of the mechanical battery swapping time, the communication confirmation time, and the time margin. The mechanical battery swapping time encompasses the total duration of unlocking, removal, insertion, and locking actions, and is calibrated after multiple action measurements of the mechanical battery swapping mechanism during the system debugging phase. The communication confirmation time is the time required for the EMS, BMS, and mechanical battery swapping mechanism to complete a handshake confirmation. The time margin covers fluctuations in mechanical actions and communication retry. All three are preset parameters. In the typical configuration of this embodiment, the mechanical battery swapping time is 45 seconds, the communication confirmation time is 5 seconds, the time margin is 15 seconds, and the expected battery swapping time window is 65 seconds.

[0029] The bypass power requirement is the sum of the power of the load to be supplied and the conversion losses. The load to be supplied refers to the total power of the critical loads that must be continuously powered during the battery swapping period. The conversion losses are pre-calibrated based on the rated power of the bypass power supply and the converter efficiency curve. The bypass energy requirement is the product of the bypass power requirement and the expected battery swapping time window. The available energy of the bypass power supply should not be less than the bypass energy requirement. For scenarios with approximately constant load, this is equivalent to the available energy of the bypass power supply divided by the bypass power requirement, resulting in a sustainable time that is not shorter than the expected battery swapping time window. Both constraints must be met simultaneously.

[0030] In this embodiment, non-critical loads are loads pre-marked as "temporarily disconnectable" in the EMS load priority configuration table. These loads are configured by maintenance personnel according to business needs before system commissioning. Their disconnection does not affect the core operating functions of the battery swapping power supply system. After disconnecting non-critical loads, the power of the loads awaiting power supply is reduced accordingly, and the bypass power and bypass energy requirements decrease, making it possible to pass the capacity verification again.

[0031] The working principle and beneficial effects of the above technical solution: The bypass capability verification covers both instantaneous power constraints and energy constraints, avoiding the shortcomings of only verifying instantaneous power while ignoring the duration of bypass power supply. When the bypass capability is insufficient, non-critical loads are prioritized for recalculation to maximize the use of existing bypass margins; if the recalculation still fails, battery swapping is rejected and the branch to be swapped out is kept powered, preventing the risky initiation of mechanical battery swapping when the bypass capability is insufficient, effectively ensuring the continuous power supply safety of the DC bus.

[0032] Example 3: Based on Example 1, the setting of the bypass latch flag and the generation of mechanical battery swapping permission include: When the bypass capability verification is passed, the output power reference value of the bypass power supply is increased according to the restricted slope, and the output power reference value of the battery branch to be replaced is decreased according to the power balance relationship. The bypass stability condition is defined as the time during which the DC bus voltage deviation, DC bus voltage change rate, and bypass power supply load rate are all within their respective stable ranges and remain stable. After the bypass stability condition is met and the output power of the battery branch to be replaced is reduced to the isolation power range, the drive of the SST power unit corresponding to the battery branch to be replaced is stopped, and the main contactor of the battery to be replaced connected to the battery branch to be replaced is disconnected. The conditions for mechanical battery swapping interlocking are: the current of the battery branch to be swapped is lower than the isolation current threshold, the main contactor of the battery to be swapped is disconnected, the residual voltage of the battery branch to be swapped is lower than the safe residual voltage threshold, and the mechanical battery swapping mechanism is ready. A mechanical battery swapping permit is generated when the mechanical battery swapping interlocking conditions are met; if any condition in the mechanical battery swapping interlocking conditions fails, the mechanical battery swapping permit is revoked and the bypass latching flag is maintained.

[0033] In this embodiment, the restricted slope is the maximum permissible increment per second of the bypass power supply output power reference value. Its purpose is to suppress the charging surge current and voltage overshoot generated on the DC bus capacitor when the bypass power supply is quickly connected. It is calibrated according to the DC bus equivalent capacitance, bypass power supply output impedance and permissible bus voltage overshoot, and is typically taken as 20% / s of the rated bypass power.

[0034] In this embodiment, a "continuous stability confirmation time" is introduced into the bypass stability condition to eliminate the misjudgment scenario where the bus voltage briefly enters the stable range due to interference and then quickly deviates. Without setting a duration threshold, the bus voltage might occasionally meet the deviation threshold during transient oscillations, triggering subsequent actions. This could lead to the generation of a mechanical power swapping permit before the bypass has truly stabilized, posing a safety risk. In the typical configuration of this embodiment, the bus voltage deviation threshold is 1.5% of the rated bus voltage, the bus voltage change rate threshold is 20V / s, the bypass power supply load rate stability upper limit is 95%, and the stability confirmation time is 1.0s.

[0035] In this embodiment, the isolation current threshold is the maximum branch current that the main contactor of the battery to be replaced is allowed to safely disconnect, determined by the disconnecting current specification of the main contactor of the battery to be replaced, with a typical value of 2A. The safe residual voltage threshold is the upper limit voltage at which the residual voltage of the branch of the battery to be replaced drops to allow mechanical personnel to access and operate it, determined by the personnel contact safety voltage standard, with a typical value of 60V. The mechanical battery swapping interlocking conditions require that the above four conditions be met simultaneously. If any condition is not met, a mechanical battery swapping permit is not allowed to be generated; if any condition fails after the permit is generated, the permit is immediately revoked, mechanical operation is suspended and the bypass latch is maintained, and it can only be resumed after the conditions are met again.

[0036] The working principle and beneficial effects of the above technical solution: This invention combines bypass stabilization, battery branch current reduction, main contactor disconnection, residual voltage safety, and mechanical readiness state into a hard interlocking condition, ensuring that the mechanical battery swapping action is strictly delayed after the establishment of electrical steady state and the electrical isolation of the battery branch. This reduces the risk that mechanical unlocking may occur before the electrical safety conditions are met in existing solutions. The design of immediately revoking the mechanical battery swapping permission when any interlocking condition fails further ensures the electrical safety during the battery swapping process.

[0037] Example 4: Based on Example 1, the connection of the battery to be replaced includes: After the battery to be replaced in the battery branch is installed and mechanically locked, the identity information, rated parameters, connection polarity and insulation status of the battery to be replaced are verified to obtain the access verification result. When the access verification result is passed, and the voltage, temperature and state of charge of the battery to be replaced are within the corresponding allowable range, the battery to be replaced is precharged through the precharge branch, and the precharge voltage difference between the battery to be replaced and the DC bus and the precharge current flowing through the precharge branch are obtained. When the pre-charge differential voltage is lower than the differential voltage threshold and the pre-charge current is lower than the pre-charge termination current threshold, and the pre-charge confirmation time continues, the main contactor of the battery to be replaced connecting the battery to be replaced and the SST power unit is closed, and the pre-charge branch is disconnected. When the access verification result is unsuccessful or the pre-charging is incomplete, the main contactor of the battery to be replaced must not be closed and the bypass latching flag must be maintained.

[0038] In this embodiment, the access verification includes the following four items, each of which must pass before entering the pre-charging stage: Identity information verification checks the consistency of the battery pack identification code, communication protocol version, and system configuration of the battery to be replaced; Rated parameter verification checks the matching of the rated voltage and rated capacity of the battery to be replaced with the current battery swapping power supply system configuration; Connection polarity verification confirms that the positive and negative terminals are not reversed through connector coding; Insulation status verification measures the insulation resistance between the positive and negative terminals and the casing using an insulation detection device, and if it is lower than a preset threshold, it is considered a failure. If any of the above items fails, the access verification result is deemed a failure, and entry into the pre-charging stage is prohibited to prevent safety accidents caused by incorrect battery packs, reverse connections, or insulation failures.

[0039] In this embodiment, the pre-charge branch is composed of a pre-charge contactor and a pre-charge resistor connected in series. During the pre-charge process, the pre-charge resistor limits the current. As the voltage on the side of the battery to be replaced tends to be consistent with the DC bus voltage, the current flowing through the pre-charge resistor gradually decreases to near zero.

[0040] According to the well-known physical laws of RC circuits, the analytical model of the current during the pre-charge stage satisfies: ; in, For time The changing real-time precharge current; The duration of precharge flow after the precharge circuit is closed; The initial value of the voltage difference between the battery to be replaced and the DC bus at the instant the pre-charge circuit is closed; The system resistance value of the configured pre-charge resistor; This is the capacitance value of the equivalent capacitance of the system's DC bus; It is a natural constant.

[0041] This analytical model shows that as the bus capacitor charges, the pre-charge current... Over time It exhibits strict exponential decay, and the decay rate is determined by the product of the pre-charge resistance and the bus equivalent capacitance (time constant).

[0042] When the pre-charge differential voltage is lower than the differential voltage threshold and the pre-charge current is lower than the pre-charge termination current threshold, and the pre-charge confirmation time continues, the pre-charge is determined to be complete. The main contactor of the battery to be replaced is then closed, and the pre-charge branch is disconnected. The pre-charge confirmation time is introduced to eliminate momentary misjudgments caused by sensor noise, ensuring that the main contactor closes only after the voltage on the bus side and the battery side is truly balanced, thus eliminating the closing inrush current.

[0043] In the typical configuration of this embodiment, the pre-charge resistance is 20Ω, the differential voltage threshold is 30V, the pre-charge termination current threshold is 1.5A, the pre-charge confirmation time is 100ms, and the pre-charge timeout determination time is 2s. After the timeout, it is determined that the pre-charge is not completed, the main contactor of the battery to be replaced is prohibited from being closed, the system enters the safety holding state and maintains the bypass latching flag.

[0044] The working principle and beneficial effects of the above technical solution: This invention achieves multiple protections through sequential verification of identity, polarity, insulation, voltage, temperature, and state of charge, effectively reducing the risk of safety accidents caused by incorrect packaging, reverse connection, and insulation abnormalities. The current-limiting pre-charge design ensures that the main contactor closes after the bus and battery side voltages are basically balanced, eliminating the closing inrush current. If any verification fails or pre-charge is not completed, the main contactor is prohibited from closing and a bypass latch is maintained, ensuring that the system is always in a bypass protection state when the battery to be replaced has not been fully verified.

[0045] Example 5: Based on Example 1, the determination of the SST power unit grouping and the five-phase load restoration sequence includes: Obtain the current output power of the bypass power supply, determine the difference between the load demand power and the current output power as the SST to be undertaken power, and determine the number of power units to be put into operation based on the SST to be undertaken power and the available power of each SST power unit after temperature derating and voltage derating. Multiple SST power units are divided into multiple power unit groups. First, the smallest power unit group, determined by the number of power units to be put into operation and capable of meeting the power of the load to be supplied, is put into operation according to the principle of having the fewest power units. After the smallest power unit group completes soft start, the DC side current stabilizes and the temperature does not exceed the limit, the subsequent power unit groups are put into operation in sequence until the total available power of the put-in SST power units is not less than the power to be supplied by the SST. The recovery order of the five-phase load is determined based on the recovery priority, starting impact parameters, and interphase coupling parameters of each phase load. The power reference value or current reference value of the corresponding load is increased phase by phase according to the recovery order of the five-phase load.

[0046] The SST's required power is the difference between the load demand power and the current output power of the bypass power supply. It represents the additional power that the SST needs to handle after the battery to be replaced is connected, assuming the bypass power supply has already handled part of the load. It should be noted that the load demand power here refers to the real-time total load demand during the SST's deployment phase, which differs from the meaning of the required power supply load used in the bypass capability verification in Example 2: the latter only refers to critical loads that must be continuously powered during battery swapping, while the former includes all loads that need to be restored after battery swapping (including non-critical loads that were disconnected before battery swapping).

[0047] The usable power of each SST power unit after temperature derating and voltage derating is determined by the following formula: ; in, For the first The current derated available power of each SST power unit; For the first Rated power of each SST power unit; For the first The temperature derating factor of each power unit is determined by a piecewise linear function based on the ratio of the current junction temperature to the rated junction temperature of the power unit. When the junction temperature exceeds the rated value, the derating factor is less than 1. For the first The voltage derating factor of each power unit is determined by a piecewise linear function based on the ratio of the current DC bus voltage to the rated bus voltage.

[0048] Number of power units to be put into operation Determine using the following formula: ; in, The summation is based on the number of power units involved (sorted in descending order of derating available power and then summed sequentially). The power to be undertaken by SST; The minimum number of power units required to ensure that the total available power is not less than the power to be undertaken by SST is determined.

[0049] In this embodiment, the five-phase load restoration order is determined according to the following three-level rules: First, the restoration priority indicates the service importance level of each phase load, which is preset by the maintenance personnel during the system configuration phase, and the phase with higher priority is restored first; Second, among phases with the same priority, they are sorted in ascending order of starting impact parameters, with the phase with the smaller starting impact parameter restored first. The starting impact parameter is the ratio of the peak current generated by each phase load at the moment of connection to the rated current of that phase, which is determined by the type and impedance characteristics of each phase load and can be obtained by step response measurement during the system commissioning phase; In addition, two phases with large interphase coupling parameters are not arranged for restoration adjacently to avoid the superimposed impact of the two phases exceeding the bus's bearing capacity. The interphase coupling parameter is the disturbance amplitude of the DC bus voltage or current of other phases when one phase load is connected, which can be obtained by bus response measurement when each phase is connected separately during the system commissioning phase. When the starting impact parameters of multiple phases are all lower than the preset proportional threshold of the rated phase current, and the bus power margin meets the requirements for parallel connection, multi-phase parallel restoration is allowed to shorten the overall restoration time.

[0050] The order of activation of each power unit group can be rotated according to the cumulative running time, that is, the power unit with the shorter cumulative running time is activated first to balance the aging speed of each module. In the typical configuration of this embodiment, the battery swapping power supply system includes eight SST power units with a rated power of 62.5kW. The five-phase load is restored in the order of A, C, E, B, D. The starting impact of phase E and phase B is less than 20% of the rated phase current. When the bus power margin is greater than 30kW, two phases are allowed to be restored in parallel.

[0051] The working principle and beneficial effects of the above technical solution: In this invention, the grouping of SST power units avoids concentrated overcurrent and thermal stress accumulation caused by the simultaneous startup of all modules. Each group completes soft start and temperature check before releasing the next group, improving the orderliness and safety of the startup process. The five-phase load recovery order is determined according to a three-level rule based on recovery priority, startup impact parameters, and interphase coupling parameters, effectively avoiding bus voltage fluctuations caused by the simultaneous startup of high-impact phases. When the constraints are met, low-impact phases are allowed to recover in parallel, effectively shortening the overall load recovery time.

[0052] Example 6: Based on Example 1, the four recovery parameters and load recovery status are determined as follows: The DC bus allowable voltage range is preset, and the difference between the DC bus voltage and the nearest boundary value in the DC bus allowable voltage range is determined as the DC bus voltage margin. Calculate the average current of the five phases of the five-phase load, and determine the unbalance of the five-phase current based on the deviation of each phase current from the average current of the five phases. Obtain the allowable temperature of the SST power unit, and determine the difference between the allowable temperature of the SST power unit and the highest temperature among all SST power unit temperatures as the SST power unit temperature margin. Obtain the current output power of the branch of the battery to be replaced, and determine the difference between the allowable output power of the battery to be replaced and the current output power as the power margin of the battery to be replaced. Set warning thresholds and severe over-limit thresholds for the four recovery parameters respectively. Compare the four recovery parameters with the corresponding warning thresholds and severe over-limit thresholds to obtain the recovery parameter status level for each recovery parameter. Based on the recovery parameter status level with the highest risk, determine the load recovery status as normal status, warning status, or severe over-limit status.

[0053] The DC bus voltage margin is determined by the following formula: ; in, This is the DC bus voltage margin; This is the current voltage of the DC bus; and These are the lower and upper boundary values ​​of the preset allowable DC bus voltage range, respectively. The smaller value is chosen because the risk of bus voltage comes from approaching either boundary, and the margin should reflect the allowance to the nearest boundary rather than the distance to a fixed end. The smaller the value, the closer the bus voltage is to the boundary of the allowable range, and the higher the risk.

[0054] The five-phase current imbalance is determined by the following formula: ; in, The average current of the five phases; For the first Phase load current; The five-phase current imbalance is measured as a percentage of the absolute value of the difference between the single-phase current with the largest deviation and the average current of the five phases. The maximum deviation is used instead of the root mean square deviation in order to capture the extreme imbalance state of the most dangerous phase.

[0055] The SST power cell temperature margin is the difference between the allowable temperature of the SST power cell and the highest temperature among all current power cell temperatures; the allowable temperature of the SST power cell is determined by the junction temperature limit in the power device datasheet. The highest temperature is used because the power cell with the highest temperature determines the thermal safety margin of the entire SST power cell group. The replacement battery power margin is the difference between the allowable output power of the replacement battery and the current output power of the replacement battery branch; the allowable output power of the replacement battery is calculated in real time by the replacement battery BMS based on its state of charge, temperature, and health status and reported through the communication interface.

[0056] The warning thresholds and severe over-limit thresholds for each recovery parameter are set according to the following principles: the warning threshold is set at the boundary where the system can complete the current recovery operation within the remaining margin without triggering a severe over-limit, and the severe over-limit threshold is set at the critical point where continued operation will lead to irreversible damage or direct pressure loss. The rules for determining the status level of each recovery parameter are as follows: when the recovery parameter is higher than the corresponding warning threshold, the recovery parameter status level is normal; when the recovery parameter is lower than the corresponding warning threshold but higher than the corresponding severe over-limit threshold, the recovery parameter status level is warning; when the recovery parameter is lower than or equal to the corresponding severe over-limit threshold, the recovery parameter status level is severe over-limit. The load recovery status is determined by the highest risk level among the four recovery parameter status levels; that is, if any one reaches the severe over-limit level, the load recovery status is severe over-limit; if any one reaches the warning level and none reaches the severe over-limit level, it is a warning status; and if all four are at the normal level, it is a normal status.

[0057] In the typical configuration of this embodiment, the warning threshold for DC bus voltage margin is 2% of the rated bus voltage, and the severe over-limit threshold is 1% of the rated bus voltage; the warning threshold for five-phase current imbalance is 15%, and the severe over-limit threshold is 25%; the warning threshold for SST power unit temperature margin is 15°C, and the severe over-limit threshold is 5°C; the warning threshold for the power margin of the battery to be replaced is 10% of the rated power of the battery to be replaced, and the severe over-limit threshold is 3% of the rated power of the battery to be replaced.

[0058] The working principle and beneficial effects of the above technical solution: The four recovery parameters comprehensively characterize the system's safety margin during the five-phase load recovery process from four dimensions: bus voltage, current distribution balance, power device thermal state, and battery output capability, covering the main sources of risk that may occur during the recovery process. Through the graded judgment of warning thresholds and severe over-limit thresholds, a three-level response mechanism is realized from normal recovery to speed reduction protection and then to rollback, avoiding control abrupt changes caused by a single threshold and making the load recovery process robust.

[0059] Example 7: Based on Example 6, the first recovery slope and the second recovery slope are determined as follows: The direction of parameter change is determined based on the difference between the four recovery parameters of the current control cycle and the four recovery parameters of the previous control cycle. Among them, the direction of increased risk is the decrease in DC bus voltage margin, the increase in five-phase current imbalance, the decrease in SST power unit temperature margin, and the decrease in the power margin of the battery to be replaced. Based on the distance between the four recovery parameters and the corresponding early warning thresholds and severe over-limit thresholds, as well as the direction of parameter change, the risk characterization value corresponding to each recovery parameter is determined, and the slope limit level is determined based on the risk characterization value with the highest risk level. Based on the pre-set base recovery slope, when the slope limit level is normal, a first recovery slope is generated based on the base recovery slope; when the slope limit level is warning level, the base recovery slope is decayed based on the risk characterization value with the highest risk level to generate a second recovery slope; when the slope limit level is severe over-limit level, a load phase rollback command is generated to roll back the most recently recovered phase to the previous stable reference value. Based on the preset slope change limit of adjacent control cycles and the remaining available power of the SST power units that have been put into operation, the first recovery slope or the second recovery slope is limited.

[0060] In this embodiment, the risk characterization value is only valid when the recovery parameter is within the warning range, i.e., the recovery parameter is lower than the warning threshold and higher than the severe over-limit threshold. When the recovery parameter is higher than the warning threshold (normal range), the corresponding risk characterization value is zero, and the slope limit level is normal. When the recovery parameter is lower than or equal to the severe over-limit threshold, the severe over-limit level determination is directly triggered, and the risk characterization value is not calculated.

[0061] Within the warning interval, let the first... The current value of the item recovery parameter is The corresponding warning threshold is (i.e., in Example 6, the first) The warning threshold set for the recovery parameter), and the corresponding severe over-limit threshold are: (i.e., in Example 6, the first) If the recovery parameter setting exceeds the severe threshold, then the first... Risk characterization value of recovery parameter Determine using the following formula: ; The fractional part represents the normalized distance of the recovery parameter from the severe exceedance threshold within the warning interval, with a value range of [value missing]. The closer the value is to 1, the closer it is to the severe threshold, and the higher the risk. For direction weighting coefficients, when the first... When the direction of change of the recovery parameter is in the direction of increasing risk, take When the direction of change is the direction of risk reduction, take ; The directional amplification factor is pre-calibrated, typically 0.5. Its physical meaning is that, with the same margin, a parameter evolving in the deteriorating direction should produce a stronger slope suppression response than a parameter evolving in the improving direction.

[0062] The maximum value among the four risk characteristics within the current control period is used to determine the slope limit level: when all four recovery parameters are higher than their respective warning thresholds, The slope limit level is normal; when at least one recovery parameter is in the warning range, The slope limit level is a warning level; when at least one recovery parameter is lower than or equal to the severe over-limit threshold, the slope limit level is a severe over-limit level.

[0063] The slope generation rule is determined by the following formula: ; in, The pre-defined base recovery slope; The slope attenuation sensitivity coefficient represents... For each increase of 1, the percentage decrease in the basic recovery slope must satisfy the following condition: When the maximum value within the warning interval is taken, the attenuated slope is not lower than the preset minimum recovery slope, typically ranging from 0.6 to 0.9. At the normal level, the first recovery slope is equal to the base recovery slope, and is output only after being limited by the remaining available power and the slope change limit of adjacent cycles. At the warning level, the calculation result of the above formula is output as the second recovery slope after being limited in the same way. At the severe over-limit level, no recovery slope is output; instead, a load phase back-off command is generated. The controller backs the power reference value or current reference value of the most recently recovered phase to the previous stable reference value, and the completion of the back-off is monitored by the state update process in Example 8.

[0064] The remaining available power of the SST power units already in operation is the difference between the sum of the available power of each power unit and the current actual total output power. This is used to ensure that the single-cycle power increment corresponding to the recovery slope multiplied by the control cycle duration does not exceed the current power supply capacity of the system. The slope change limit between adjacent control cycles is used to prevent drastic fluctuations in the slope between adjacent cycles, ensuring a smooth slope adjustment process.

[0065] In the typical configuration of this embodiment, The minimum recovery slope is taken as 10% of the rated phase power / s, the maximum recovery slope is taken as 2% of the rated phase power / s, and the maximum recovery slope is taken as 15% of the rated phase power / s. , The limit for the slope change between adjacent control cycles is 2% of the rated phase power / s.

[0066] The working principle and beneficial effects of the above technical solution: This invention maps the normalized position and trend of recovery parameters into a risk characterization value, so that the adjustment of the recovery slope responds to both the current margin status and the trend of change. When the margin narrows rapidly, it can slow down in advance and avoid passive regression after exceeding the limit. The directional weighting coefficient produces stronger slope suppression for parameters that change in the direction of deterioration, while not excessively restricting the recovery speed when changing in the direction of improvement, thus achieving a balance between safety and recovery efficiency.

[0067] Example 8: Based on Example 1, the state update process includes: After changing the power reference value or current reference value of the current recovery phase, the four recovery parameters are reacquired after the operation parameter response confirmation time. The four newly acquired recovery parameters are compared with the four recovery parameters before the power reference value or current reference value of the current recovery phase was changed, so as to obtain the trend of the recovery parameter change corresponding to each recovery parameter. When the DC bus voltage margin, SST power unit temperature margin, or battery power margin to be replaced increases, or the five-phase current imbalance decreases, the corresponding recovery parameter change trend is determined to be a change towards safety; when the change direction is opposite, the corresponding recovery parameter change trend is determined to be a change towards risk. When all recovery parameters change in a safe direction or remain stable, continue to restore the current recovery phase, and release the next recovery phase after the current recovery phase stabilizes; when at least one recovery parameter changes in a risk direction for a preset number of control cycles, maintain the power reference value or current reference value of the current recovery phase; when at least one recovery parameter reaches the corresponding severe over-limit threshold, revert the most recent recovery phase to the previous stable reference value. The load recovery status for the next control cycle is determined based on the four reacquired recovery parameters.

[0068] In this embodiment, the operating parameter response confirmation time is the delay required for the DC bus voltage, phase currents, SST power unit temperature, and output power of the branch to be replaced battery to tend towards a new steady state after changing the power reference value or current reference value of the current recovery phase. Setting this delay time is necessary: ​​if the four recovery parameters are sampled immediately after the control action is issued, the collected values ​​will be intermediate values ​​during the transient response process, potentially leading to misjudgments of the actual system state. The operating parameter response confirmation time should be set to no less than 3 to 5 time constants of the slowest-responding physical quantity in the system (usually the SST power unit temperature), typically 3 to 5 control cycles.

[0069] In this embodiment, the method for judging the trend of the recovery parameter change is as follows: the newly acquired recovery parameter value is compared with the recovery parameter value recorded before the power reference value or current reference value is changed item by item. If the new value of the DC bus voltage margin, SST power unit temperature margin or the power margin of the battery to be replaced is greater than the old value, or the new value of the five-phase current imbalance is less than the old value, then the corresponding parameter changes in the safe direction; otherwise, it changes in the risk direction; if the new and old values ​​are equal, it is considered to remain stable.

[0070] In this embodiment, the previous stable reference value is the most recent value recorded after the power reference value or current reference value of the current recovery phase is confirmed to be stable by the state update process before the current recovery phase starts its current round of increase operation; each time the state update process determines that "the current recovery phase is stable", the value is updated and saved as a safe landing point for the rollback operation in case of serious over-limit.

[0071] The reason for setting a threshold for continuous multi-cycle detection instead of single-cycle detection is that a small change in the recovery parameter towards the risk direction within a single control cycle may originate from measurement noise rather than a deterioration of the actual system state; triggering the hold operation only after several consecutive control cycles of continuous change towards the risk direction can filter out noise interference and prevent excessive hysteresis in the response. A typical value for the preset number of consecutive control cycles is 3 control cycles.

[0072] The working principle and beneficial effects of the above technical solution: In this invention, the state update process introduces a waiting mechanism through the response confirmation time of the running parameters to avoid making incorrect judgments based on transient data before the control action has fully taken effect on the physical system; the robustness of the state judgment is improved by filtering measurement noise through detection conditions that change in the direction of risk over multiple consecutive cycles; and the rollback to the previous stable reference value provides a clear safe recovery point for the system in extreme cases, avoiding the infinite loop caused by unlimited load reduction in the recovery process.

[0073] Example 9: Based on Example 1, the bypass exit condition and the reset of the bypass latch flag include: After the bypass latch flag is set, maintain the power supply connection between the bypass power supply and the DC bus; After the five-phase load stabilizes, the output power of the SST power units that have been put into operation is increased and the output power of the bypass power supply is reduced according to the power complementarity relationship. The following conditions are defined as bypass exit conditions: the absolute value of the output power of the bypass power supply is lower than the zero power threshold, the parallel circulating current between the bypass power supply and the SST power unit that has been put into operation is lower than the circulating current threshold, there is no reverse power transmitted from the DC bus to the bypass power supply, and the voltage deviation and voltage change rate of the DC bus are both within the corresponding stable range and continue to exit the confirmation time. When the bypass exit condition is met, the bypass switch is disconnected and the bypass latch flag is reset; The bypass latch flag must not be reset when the battery to be replaced is not connected, the SST power unit grouping is not completed, the load recovery status is in a severely over-limit state, or the bypass exit condition is not met.

[0074] In this embodiment, the power complementarity relationship means that during the bypass shutdown process, the increase in output power of the SST power units already in operation within each control cycle is equal to the decrease in output power of the bypass power supply. This ensures that the total power supply of the DC bus remains constant within each control cycle, avoiding instantaneous power gaps caused by power transfer rate mismatch. The bypass shutdown slope is the maximum decrease per second in the reference value of the bypass power supply output power, typically taken as 20 kW / s; the reference value of the output power of the SST power units already in operation increases at the same rate.

[0075] In this embodiment, parallel circulating current detection and reverse power detection are introduced into the bypass exit condition for the following reasons: There is a parallel power supply relationship between the bypass power supply and the already activated SST power unit. If there is a voltage deviation between the two, circulating current will be generated, indicating that the power distribution has not yet reached balance. If the bypass power supply output voltage is lower than the DC bus voltage, reverse power will flow from the bus to the bypass power supply. Reverse power indicates that the bypass power supply has changed from a power supplier to a power consumer. At this time, forcibly disconnecting the bypass switch will cause an instantaneous power shortage on the bus. All four conditions must be met simultaneously and for a continuous exit confirmation time before it can be determined that the power transfer has been fully completed, allowing the bypass switch to be disconnected. In the typical configuration of this embodiment, the zero power threshold is 4kW, the circulating current threshold is 3A, and the exit confirmation time is 0.5s.

[0076] In this embodiment, four conditions under which the bypass latch flag cannot be reset form a fallback protection: Resetting is prohibited when the battery to be replaced is not yet connected, ensuring that bypass protection is not removed during battery calibration or pre-charging; resetting is prohibited when the SST power unit grouping is not yet completed, ensuring that bypass protection is not removed during the power unit startup surge phase; resetting is prohibited when the load recovery state is in a severely over-limit state, ensuring that the bypass is always online when the system is in its most dangerous state; and resetting is prohibited when the bypass exit condition is not met, ensuring that the bypass is not forcibly exited when power transfer is insufficient.

[0077] The working principle and beneficial effects of the above technical solution: This invention utilizes a power complementary ramp-off mechanism to ensure that the total power supply of the DC bus remains balanced during bypass shutdown, eliminating the power gap caused by hard cut-off. Multiple joint judgment conditions confirm from multiple dimensions that the power transfer between the bypass and SST has been fully completed, avoiding premature disconnection of the bypass switch before the bypass current returns to zero or the system is stable. The strict reset prohibition condition of the bypass latch flag provides full safety assurance for the entire battery swapping control process.

[0078] Example 10: This example provides an SST control system with battery swapping bypass latch and five-phase load recovery, used to execute the SST control method described in any one of Examples 1 to 9, such as... Figure 2 As shown, it includes a controller, DC bus, bypass power supply, bypass switch, battery branch to be swapped out, battery branch to be swapped in, mechanical battery swapping mechanism, multiple SST power units, five-phase load, main contactor for battery to be swapped out, main contactor for battery to be swapped in, precharge branch and sampling unit; The bypass power supply is connected to the DC bus through a bypass switch. The battery branch to be replaced is connected to the corresponding SST power unit through the main contactor of the battery to be replaced. The battery branch to be replaced is connected to the corresponding SST power unit through the main contactor of the battery to be replaced. The battery branch to be replaced is also connected to the DC bus through a precharge branch. The SST power unit is connected to the DC bus. The five-phase load is powered by the DC bus. The sampling unit is connected to the controller. The sampling unit is used to collect the voltage of the DC bus, the phase current of each phase of the five-phase load, the temperature of the SST power unit, the output power of the bypass power supply, the output power of the battery branch to be replaced, and the voltage, temperature and state of charge of the battery to be replaced in the battery branch. The controller is used to obtain the power of the load to be supplied and the available power and energy of the bypass power supply. Based on the power of the load to be supplied, the expected battery swapping time window, and the available power and energy of the bypass power supply, the bypass capability is checked. When the bypass capability check is passed, the bypass latch flag is set. When the bypass stability condition is met and the battery branch to be swapped out is electrically isolated, the mechanical battery swapping permission is output to the mechanical battery swapping mechanism. The controller is also used to group and activate the SST power units according to the load demand power, the available power of the SST power unit and the allowable output power of the battery to be replaced after the battery is connected, and restore the five-phase load phase by phase according to the five-phase load restoration order. The controller is also used to determine the load recovery status based on the DC bus voltage margin, five-phase current imbalance, SST power unit temperature margin and the power margin of the battery to be replaced, and to control the current recovery phase to continue to recover, reduce the recovery slope or fall back to the previous stable reference value according to the load recovery status. The controller is also used to transfer the load power from the bypass power supply to the activated SST power unit after the five-phase load has stabilized, and to disconnect the bypass switch and reset the bypass latch flag when the bypass exit condition is met.

[0079] In this embodiment, the controller can be centrally deployed in the same processing unit, or it can be implemented in a distributed manner by the Energy Management System (EMS), SST controller, BMS, and mechanical battery swapping mechanism controller. In the distributed deployment, each control node shares a unified status number, timestamp, and interlocking word, and achieves status synchronization through a communication bus. The unified status number ensures that each node knows the current stage of the battery swapping process, and the interlocking word enables any node to promptly notify other nodes of changes in interlocking conditions, preventing timing misalignment due to a lack of shared status information.

[0080] In this embodiment, the voltage, temperature, and state of charge of the battery to be replaced in the sampling unit are obtained through a communication interface with the battery management system (BMS) of the battery to be replaced, rather than being directly measured. The BMS calculates the state of charge and the current allowable output power in real time based on its internal battery model and reports it to the controller via a communication bus such as CAN or Ethernet. The time delay for the controller to read the above information must be less than the judgment period for bypass capability verification and battery access verification to ensure data real-time performance.

[0081] In this embodiment, such as Figure 3 As shown, the controller operates according to a unified control state machine, including the normal power supply state. Bypass preparation status Bypass latch status Battery replacement branch exit status Battery to be replaced and pre-charge status SST power recovery status Five-phase load recovery status Bypass exit status and safety maintenance and abnormal rollback status . to This will enter the state if any of the following occurs: DC bus over-limit, insufficient bypass remaining capacity, insulation failure, polarity error, pre-charge timeout, module over-temperature, inconsistent contactor feedback, or abnormal mechanical condition. ; The bypass latch flag remains set while the mechanical power swap permission is frozen, preventing the activation of new SST power units or load phases; after the fault is cleared, the status will return based on the bypass availability. Continue execution or return to restart.

[0082] In this embodiment, the controller also includes an event recording unit for storing the battery swapping request time, bypass capability prediction input and result, bypass lock setting and reset time, the status of each component of the mechanical battery swapping interlock condition, the action sequence of the main contactor of the battery to be swapped out and the main contactor of the battery to be swapped in, the time change process of pre-charge voltage difference and pre-charge current, the grouping and activation sequence of SST power units and the soft start completion time of each group, the five-phase load recovery sequence and the real-time slope of each control cycle, abnormal rollback events and their triggering reasons, and the power transfer sequence during the bypass exit process. The event recording data is used for fault tracing and can be used to self-tun and optimize parameters such as mechanical battery swapping time calibration value, pre-charge resistance value, and basic recovery slope after multiple battery swaps are completed.

[0083] The working principle and beneficial effects of the above technical solution: This system integrates all functional modules required for the entire battery swapping process into a single controller. The modules are coordinated through a unified state machine state number and interlocking word, eliminating timing misalignment and interlocking deficiencies caused by the lack of shared state information between independent controllers. The sampling unit covers the physical quantities required to execute all the above control logic. The event recording unit provides a complete data foundation for fault tracing and parameter self-tuning.

[0084] In a typical application scenario of this embodiment, the battery swapping power supply system has a rated power of 500kW, a DC bus rated voltage of 750V, an SST consisting of eight power units with a rated power of 62.5kW each, a bypass power supply with a rated continuous power of 200kW and available energy of 2.4kWh, and a five-phase load with a rated total power of 200kW. The typical configuration of the key control parameters for this system is as follows: The typical bypass power safety margin is 20kW, used to pre-allocate and cover prediction errors and transient impacts; the battery swapping time margin is 15s; the bus stability deviation threshold is 1.5%; the bus change rate threshold is 20V / s; the branch isolation current threshold is 2A; the safety residual voltage threshold is 60V; the pre-charge resistance is 20Ω; the pre-charge termination voltage difference is 30V; the base recovery slope is 10% of the rated phase power / s; and the bypass exit slope is 20kW / s.

[0085] The specific process of the entire battery swapping process is as follows: During the 0s to 2s phase, the system is in a normal power supply state. The current total load is 160kW, of which 120kW is critical load (load power to be guaranteed), and 40kW is non-critical load that can be reduced. The available bypass power is 200kW, and the available energy is 2.4kWh. The estimated battery swapping time window is the sum of the mechanical swapping time (45s), the communication confirmation time (5s), and the time margin (15s), totaling 65s. Maintaining the full 160kW load, the bypass energy requirement is 160kW multiplied by 65s and converted to kWh, approximately 2.89kWh, which is higher than the available energy of 2.4kWh, so the bypass capability verification fails. After the controller removes the 40kW non-critical load, the bypass energy requirement drops to 120kW multiplied by 65s and converted to kWh, approximately 2.17kWh, which is lower than the available energy of 2.4kWh. Furthermore, the bypass power requirement of 120kW does not exceed the available power of 200kW, so the bypass capability verification passes, and the process proceeds. Parallel setting of bypass latch flag.

[0086] During the 2s to 5s phase, the bypass power supply output power increases from 0 to 120kW at a limited slope (20% / s of rated bypass power). After the output power of the replaced battery branch decreases from 160kW to 0kW, the bus voltage deviation is lower than 1.5% of the rated value, the rate of change is lower than 20V / s, the bypass load rate is lower than 95%, and the system remains stable for 1.0s, thus meeting the bypass stability conditions and entering the system phase. .

[0087] During the 5s to 8s phase, the drive of the SST power unit corresponding to the battery branch to be replaced is stopped, the main contactor of the battery to be replaced is disconnected, the current of the battery branch to be replaced drops below 2A, the auxiliary contact feedback of the main contactor is disconnected, the residual voltage is below 60V, and the mechanical battery swapping mechanism is ready. When all four mechanical battery swapping interlocking conditions are met simultaneously, a mechanical battery swapping permission is generated, and the system enters the process. .

[0088] During the 8s to 55s phase, the mechanical battery swapping mechanism performs unlocking, removal, insertion, and locking actions. The bypass power supply continuously powers the 120kW critical load, and the bypass latch flag remains set. Once the swapped-in battery is inserted and mechanically locked, the process continues... The system sequentially verifies the identity, polarity, insulation, voltage, and state of charge. Once all verifications are passed, pre-charging is initiated. The open-circuit voltage of the battery to be replaced is 780V, the DC bus voltage is 720V, and the pre-charging resistance is 20Ω. The initial pre-charging current is the difference between these two values ​​divided by the pre-charging resistance, which is 3A. As the bus capacitor charges, the pre-charging current decays exponentially according to the RC law. Once the pre-charging voltage difference drops below 30V and the pre-charging current is below 1.5A for 100ms, the main contactor of the battery to be replaced is closed, disconnecting the pre-charging branch.

[0089] During the 55s to 62s phase, two sets of SST power units are first activated, providing a total available power of 125kW to meet the critical load requirement of 120kW. After the two sets complete soft start and temperature checks, subsequent power unit sets are activated sequentially until the total available power meets the power required by the SST system, at which point the system enters its normal operating state. .

[0090] During the 62s to 72s phase, the five-phase load is restored in the order of A, C, E, B, D. The initial slope limit level of phase A is at the normal level, and the first restoration slope is equal to the base restoration slope 10% of the rated phase power / s; as the power of phase A increases, the DC bus voltage margin enters the warning range. The slope limit level is raised to a warning level, and the second recovery slope is calculated by multiplying the base recovery slope by [a certain factor]. The attenuation is approximately 4% of the rated phase power per second; after phase A stabilizes, phase C is released, and then they recover sequentially; the starting impact of phases E and B is less than 20% of the rated phase current, and the bus power margin is greater than 30kW, allowing parallel recovery of two phases; after all five phases stabilize, the system enters... .

[0091] During the 72s to 78s phase, the output power of the activated SST power unit increases by 20kW / s, while the output power of the bypass power supply decreases by an equal amount of 20kW / s, establishing a power complementarity relationship. Once the bypass power drops below 4kW, the parallel circulating current is less than 3A, there is no reverse power, and the bus voltage deviation is below 1.5% of the rated value and remains stable for 0.5s, the bypass exit condition is met. The bypass switch is disconnected, the bypass latch flag is reset, and the system returns to normal. All five-phase loads are powered by the SST power units that have been put into operation, with a total power of 200kW, and the entire battery swapping process is completed.

[0092] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. An SST control method with battery swapping bypass latching and five-phase load restoration, characterized in that, The method, applicable to a battery swapping power supply system including a DC bus, bypass power supply, bypass switch, battery branch to be swapped out, battery branch to be swapped in, mechanical battery swapping mechanism, multiple SST power units, five-phase load, main contactor for the battery to be swapped out, main contactor for the battery to be swapped in, and pre-charge branch, comprises: Obtain the power of the load to be supplied, the available power and energy of the bypass power supply, and verify the bypass capability based on the power of the load to be supplied, the expected battery swapping time window, and the available power and energy of the bypass power supply. When the bypass capability verification is passed, the bypass latch flag is set, which increases the output power of the bypass power supply and decreases the output power of the battery branch to be replaced. When the bypass stability condition is met and the battery branch to be replaced is electrically isolated, a mechanical battery swapping permit is generated. After the mechanical battery swap is completed, the battery to be swapped in is connected, the load demand power and the allowable output power of the battery to be swapped in are obtained, and the SST power unit is grouped and put into operation according to the load demand power, the available power of the SST power unit and the allowable output power of the battery to be swapped in. The five-phase load is restored one phase at a time according to the five-phase load restoration order. The DC bus voltage margin, five-phase current imbalance, SST power unit temperature margin, and battery power margin to be replaced are used as four recovery parameters to determine the load recovery status. When the load recovery status is normal, the current recovery phase is recovered according to the first recovery slope. When the load recovery status is warning, the current recovery phase is recovered according to the second recovery slope, which is less than the first recovery slope, and the release of the next recovery phase is paused. When the load recovery status is severely over-limit, the most recent recovery phase is rolled back to the previous stable reference value. The status update process is performed based on the four recovery parameters reacquired after control. After the five-phase load stabilizes, the load power is transferred from the bypass power supply to the activated SST power unit, and the bypass switch is disconnected and the bypass latch flag is reset when the bypass exit condition is met.

2. The SST control method with battery swapping bypass latching and five-phase load recovery as described in claim 1, characterized in that, Bypass capability verification includes: The estimated battery swapping time window is determined based on the pre-set mechanical battery swapping time, communication confirmation time, and time margin. The bypass demand power is determined based on the power of the load to be supplied and the preset conversion loss, and the bypass energy demand is determined based on the bypass demand power and the expected battery swapping time window. When the available power of the bypass power supply is not less than the bypass required power, and the available energy of the bypass power supply is not less than the bypass required energy, the bypass capability verification is deemed to have passed. If at least one condition is not met, the pre-configured non-critical load is removed and the bypass capability is re-verified; if the re-verification of the bypass capability fails, the mechanical battery swapping permit is rejected and the branch of the battery to be swapped out is kept powered.

3. The SST control method with battery swapping bypass latching and five-phase load recovery as described in claim 1, characterized in that, Setting the bypass latch flag and generating the mechanical battery swapping permission include: When the bypass capability verification is passed, the output power reference value of the bypass power supply is increased according to the restricted slope, and the output power reference value of the battery branch to be replaced is decreased according to the power balance relationship. The bypass stability condition is defined as the time during which the DC bus voltage deviation, DC bus voltage change rate, and bypass power supply load rate are all within their respective stable ranges and remain stable. After the bypass stability condition is met and the output power of the battery branch to be replaced is reduced to the isolation power range, the drive of the SST power unit corresponding to the battery branch to be replaced is stopped, and the main contactor of the battery to be replaced connected to the battery branch to be replaced is disconnected. The conditions for mechanical battery swapping interlocking are: the current of the battery branch to be swapped is lower than the isolation current threshold, the main contactor of the battery to be swapped is disconnected, the residual voltage of the battery branch to be swapped is lower than the safe residual voltage threshold, and the mechanical battery swapping mechanism is ready. A mechanical battery swapping permit is generated when the mechanical battery swapping interlocking conditions are met; if any condition in the mechanical battery swapping interlocking conditions fails, the mechanical battery swapping permit is revoked while the bypass latching flag is maintained.

4. The SST control method with battery swapping bypass latching and five-phase load recovery as described in claim 1, characterized in that, The battery to be replaced includes: After the battery to be replaced in the battery branch is installed and mechanically locked, the identity information, rated parameters, connection polarity and insulation status of the battery to be replaced are verified to obtain the access verification result. When the access verification result is passed, and the voltage, temperature and state of charge of the battery to be replaced are within the corresponding allowable range, the battery to be replaced is precharged through the precharge branch, and the precharge voltage difference between the battery to be replaced and the DC bus and the precharge current flowing through the precharge branch are obtained. When the pre-charge differential voltage is lower than the differential voltage threshold and the pre-charge current is lower than the pre-charge termination current threshold, and the pre-charge confirmation time continues, the main contactor of the battery to be replaced connecting the battery to be replaced and the SST power unit is closed, and the pre-charge branch is disconnected. When the access verification result is unsuccessful or the pre-charging is incomplete, the main contactor of the battery to be replaced must not be closed and the bypass latching flag must be maintained.

5. The SST control method with battery swapping bypass latching and five-phase load recovery as described in claim 1, characterized in that, The determination of the SST power unit grouping and the five-phase load restoration sequence includes: Obtain the current output power of the bypass power supply, determine the difference between the load demand power and the current output power as the SST to be undertaken power, and determine the number of power units to be put into operation based on the SST to be undertaken power and the available power of each SST power unit after temperature derating and voltage derating. Multiple SST power units are divided into multiple power unit groups. First, the smallest power unit group, determined by the number of power units to be put into operation and capable of meeting the power of the load to be supplied, is put into operation according to the principle of having the fewest power units. After the smallest power unit group completes soft start, the DC side current stabilizes and the temperature does not exceed the limit, the subsequent power unit groups are put into operation in sequence until the total available power of the put-in SST power units is not less than the power to be supplied by the SST. The recovery order of the five-phase load is determined based on the recovery priority, starting impact parameters, and interphase coupling parameters of each phase load. The power reference value or current reference value of the corresponding load is increased phase by phase according to the recovery order of the five-phase load.

6. The SST control method with battery swapping bypass latching and five-phase load recovery as described in claim 1, characterized in that, The four recovery parameters and load recovery status are determined as follows: The DC bus allowable voltage range is preset, and the difference between the DC bus voltage and the nearest boundary value in the DC bus allowable voltage range is determined as the DC bus voltage margin. Calculate the average current of the five phases of the five-phase load, and determine the unbalance of the five-phase current based on the deviation of each phase current from the average current of the five phases. Obtain the allowable temperature of the SST power unit, and determine the difference between the allowable temperature of the SST power unit and the highest temperature among all SST power unit temperatures as the SST power unit temperature margin. Obtain the current output power of the branch of the battery to be replaced, and determine the difference between the allowable output power of the battery to be replaced and the current output power as the power margin of the battery to be replaced. Set warning thresholds and severe over-limit thresholds for the four recovery parameters respectively. Compare the four recovery parameters with the corresponding warning thresholds and severe over-limit thresholds to obtain the recovery parameter status level for each recovery parameter. Based on the recovery parameter status level with the highest risk, determine the load recovery status as normal status, warning status, or severe over-limit status.

7. The SST control method with battery swapping bypass latching and five-phase load recovery as described in claim 6, characterized in that, The first and second recovery slopes are determined as follows: The direction of parameter change is determined based on the difference between the four recovery parameters of the current control cycle and the four recovery parameters of the previous control cycle. Among them, the direction of increased risk is the decrease in DC bus voltage margin, the increase in five-phase current imbalance, the decrease in SST power unit temperature margin, and the decrease in the power margin of the battery to be replaced. Based on the distance between the four recovery parameters and the corresponding early warning thresholds and severe over-limit thresholds, as well as the direction of parameter change, the risk characterization value corresponding to each recovery parameter is determined, and the slope limit level is determined based on the risk characterization value with the highest risk level. Based on the pre-set base recovery slope, when the slope limit level is normal, a first recovery slope is generated based on the base recovery slope; when the slope limit level is warning level, the base recovery slope is decayed based on the risk characterization value with the highest risk level to generate a second recovery slope; when the slope limit level is severe over-limit level, a load phase rollback command is generated to roll back the most recently recovered phase to the previous stable reference value. Based on the preset slope change limit of adjacent control cycles and the remaining available power of the SST power units that have been put into operation, the first recovery slope or the second recovery slope is limited.

8. The SST control method with battery swapping bypass latching and five-phase load recovery as described in claim 1, characterized in that, The state update process includes: After changing the power reference value or current reference value of the current recovery phase, the four recovery parameters are reacquired after the operation parameter response confirmation time. The four newly acquired recovery parameters are compared with the four recovery parameters before the power reference value or current reference value of the current recovery phase was changed, so as to obtain the trend of the recovery parameter change corresponding to each recovery parameter. When the DC bus voltage margin, SST power unit temperature margin, or battery power margin to be replaced increases, or the five-phase current imbalance decreases, the corresponding recovery parameter change trend is determined to be a change towards safety; when the change direction is opposite, the corresponding recovery parameter change trend is determined to be a change towards risk. When all recovery parameters change in a safe direction or remain stable, continue to restore the current recovery phase, and release the next recovery phase after the current recovery phase stabilizes; when at least one recovery parameter changes in a risk direction for a preset number of control cycles, maintain the power reference value or current reference value of the current recovery phase; when at least one recovery parameter reaches the corresponding severe over-limit threshold, revert the most recent recovery phase to the previous stable reference value. The load recovery status for the next control cycle is determined based on the four reacquired recovery parameters.

9. The SST control method with battery swapping bypass latching and five-phase load recovery as described in claim 1, characterized in that, The bypass exit conditions and the reset of the bypass latch flag include: After the bypass latch flag is set, maintain the power supply connection between the bypass power supply and the DC bus; After the five-phase load stabilizes, the output power of the SST power units that have been put into operation is increased and the output power of the bypass power supply is reduced according to the power complementarity relationship. The following conditions are defined as bypass exit conditions: the absolute value of the output power of the bypass power supply is lower than the zero power threshold, the parallel circulating current between the bypass power supply and the SST power unit that has been put into operation is lower than the circulating current threshold, there is no reverse power transmitted from the DC bus to the bypass power supply, and the voltage deviation and voltage change rate of the DC bus are both within the corresponding stable range and continue to exit the confirmation time. When the bypass exit condition is met, the bypass switch is disconnected and the bypass latch flag is reset; The bypass latch flag must not be reset when the battery to be replaced is not connected, the SST power unit grouping is not completed, the load recovery status is in a severely over-limit state, or the bypass exit condition is not met.

10. An SST control system with battery swapping bypass latching and five-phase load restoration, used to execute the SST control method with battery swapping bypass latching and five-phase load restoration as described in any one of claims 1 to 9, characterized in that, It includes a controller, DC bus, bypass power supply, bypass switch, battery branch to be swapped out, battery branch to be swapped in, mechanical battery swapping mechanism, multiple SST power units, five-phase load, main contactor for battery to be swapped out, main contactor for battery to be swapped in, precharge branch and sampling unit; The bypass power supply is connected to the DC bus through a bypass switch. The battery branch to be replaced is connected to the corresponding SST power unit through the main contactor of the battery to be replaced. The battery branch to be replaced is connected to the corresponding SST power unit through the main contactor of the battery to be replaced. The battery branch to be replaced is also connected to the DC bus through a precharge branch. The SST power unit is connected to the DC bus. The five-phase load is powered by the DC bus. The sampling unit is connected to the controller. The sampling unit is used to collect the voltage of the DC bus, the phase current of each phase of the five-phase load, the temperature of the SST power unit, the output power of the bypass power supply, the output power of the battery branch to be replaced, and the voltage, temperature and state of charge of the battery to be replaced in the battery branch. The controller is used to obtain the power of the load to be supplied and the available power and energy of the bypass power supply. Based on the power of the load to be supplied, the expected battery swapping time window, and the available power and energy of the bypass power supply, the bypass capability is checked. When the bypass capability check is passed, the bypass latch flag is set. When the bypass stability condition is met and the battery branch to be swapped out is electrically isolated, the mechanical battery swapping permission is output to the mechanical battery swapping mechanism. The controller is also used to group and activate the SST power units according to the load demand power, the available power of the SST power unit and the allowable output power of the battery to be replaced after the battery is connected, and restore the five-phase load phase by phase according to the five-phase load restoration order. The controller is also used to determine the load recovery status based on the DC bus voltage margin, five-phase current imbalance, SST power unit temperature margin and the power margin of the battery to be replaced, and to control the current recovery phase to continue to recover, reduce the recovery slope or fall back to the previous stable reference value according to the load recovery status. The controller is also used to transfer the load power from the bypass power supply to the activated SST power unit after the five-phase load has stabilized, and to disconnect the bypass switch and reset the bypass latch flag when the bypass exit condition is met.

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