Controllable anti-inrush energy-saving management system and method

Abstract

The application discloses a controllable anti-surge energy-saving management system and method, relates to the technical field of variable frequency energy-saving control, and comprises the following parts: an energy storage battery cluster used for storing and releasing electric energy; a loop protection unit connected between the energy storage battery cluster and a plurality of DC bus branches of a plurality of variable frequency devices outside, used for realizing independent on-off control and overcurrent protection of the DC bus branches; an anti-surge control module used for inhibiting surge voltage and surge current in the transient process of branch connection or disconnection; and an energy-saving management unit used for reducing the loss when the system is in steady operation. Through the time-sharing multiplexing control strategy, the bypass switch is closed to realize micro-ohm direct connection in the steady operation, the inherent contradiction between surge suppression and low loss is solved, the voltage peak when the fault branch is disconnected is inhibited through the soft removal technology, the single-point fault diffusion is prevented, and the system reliability, safety and electrical life are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of frequency conversion energy-saving control technology, and in particular to a controllable surge-proof energy-saving management system and method. Background Technology

[0002] In energy-saving retrofits of variable frequency drives (VFDs) for elevators, lifts, and other similar equipment, a parallel architecture connecting energy storage units to the DC bus is often used to recover regenerated energy. Existing technology proposes an energy recovery method based on voltage and voltage difference coordinated control (e.g., CN121417428A), which determines the timing of charging and discharging by monitoring the absolute value and rate of change of the bus voltage, thus solving the problem of false triggering.

[0003] However, this solution has the following drawbacks: First, it only focuses on the control logic and does not address the physical impact at the moment of switching: when the energy storage unit is directly connected in parallel with the bus, it will generate a surge current of thousands of amperes, which will cause the contactor to weld and the equipment to be damaged. Second, it does not take into account the contradiction between transient suppression and steady-state loss: if semiconductor devices are used for control, the steady-state conduction loss will be large, and if only the contactor is directly connected, the surge cannot be suppressed. Third, for multi-branch parallel scenarios, when a branch is disconnected due to a fault, the reverse peak voltage generated will propagate along the bus and break down other normally operating equipment, which poses a risk of single-point fault propagation. Summary of the Invention

[0004] The main objective of this invention is to provide a controllable surge-protected energy-saving management system and method. This aims to solve the technical problems of: while permanently connecting surge suppression devices in series in the DC bus main circuit can suppress switching surges, it leads to continuous conduction voltage drop and additional losses during steady-state operation, increasing the thermal management burden and contradicting energy-saving goals; and without any suppression measures, the instantaneous switching of the energy storage battery cluster and the inverter DC bus generates a surge current of thousands of amperes, causing contactor contact welding, equipment electrical stress overload, or even damage, failing to effectively meet the dual technical requirements of transient surge suppression and steady-state low loss.

[0005] To achieve the above objectives, this invention proposes a controllable surge-protected energy-saving management system, comprising: DC bus, used to connect DC bus branches of multiple frequency converters; Energy storage battery clusters are used to store and release electrical energy; The circuit protection unit is connected in series between the energy storage battery cluster and the DC bus. It is used to control the disconnection of the energy storage battery cluster and the DC bus branch when a branch fault occurs or when disconnection is required according to the energy-saving management strategy. The surge protection control module is connected in the main circuit between the energy storage battery cluster and the circuit protection unit; The energy-saving management unit is connected to the energy storage battery cluster, the surge protection control module, and the circuit protection unit respectively. The energy-saving management unit is configured to: control the surge protection control module to enter the surge suppression mode before any branch contactor in the control circuit protection unit performs a closing or opening operation; and control the surge protection control module to enter the low-loss mode after the transient process ends.

[0006] Furthermore, the surge protection control module includes a surge suppression branch and a bypass switch connected in parallel; The surge suppression branch consists of a power switch and its driving circuit, used to suppress surge voltage and surge current during the transient process of the branch being turned on or off; the drain of the power switch is connected to the positive terminal of the energy storage battery cluster, and its source is connected to one end of the bypass switch and the loop protection unit. The energy-saving management unit is also configured to: disconnect the bypass switch when the surge protection control module enters the surge suppression mode, so that the surge suppression branch can be put into operation; and close the bypass switch when the surge protection control module enters the low-loss mode, so as to bypass the surge suppression branch and reduce the loss during steady-state operation of the system.

[0007] Furthermore, the surge suppression branch also includes: An RC soft-start circuit is connected between the gate and source of a power switch to control the turn-on rate of the power switch and achieve soft start. A voltage divider resistor network is connected between the positive terminal of the energy storage battery cluster and the gate of the power switch to provide a steady-state operating voltage for the gate. A Zener diode is connected in parallel between the gate and source of a power switching transistor to clamp the gate-source voltage and protect the MOSFET.

[0008] Furthermore, the energy management unit is also configured as follows: Real-time acquisition of operating parameters of energy storage battery clusters, including total voltage, individual cell voltage, temperature and branch current; Real-time acquisition of voltage and current of each DC bus branch; When the voltage difference |VTi-Vbat| between the DC bus voltage VTi of the i-th branch and the real-time voltage Vbat of the energy storage battery cluster is less than or equal to the preset closing threshold, a closing command is generated and output to the surge protection control module so that the surge protection control module responds to the closing command and disconnects the bypass switch; then a signal is sent to the loop protection unit to close the corresponding branch contactor, and after a first preset time delay, a signal is sent again to close the bypass switch.

[0009] Furthermore, the energy management unit is also configured as follows: When the operating parameters of the energy storage battery cluster are detected to exceed the preset fault threshold, a disconnect command is generated and output to the surge protection control module to send a signal so that the surge protection control module responds to the disconnect command and disconnects the bypass switch; then a signal is sent to the loop protection unit to disconnect the corresponding branch contactor, and after a second preset time delay, a signal is sent again to close the bypass switch.

[0010] The energy management unit is also configured as follows: When the current Ik of the kth DC bus branch is detected to exceed the preset overcurrent fault threshold, an emergency disconnect command is generated and output to the surge protection control module to send a signal so that the surge protection control module responds to the emergency disconnect command and disconnects the bypass switch; then a signal is sent to the loop protection unit to disconnect the branch contactor corresponding to the kth branch, and after a third preset time delay, a signal is sent again to close the bypass switch, while maintaining the connection status of other non-faulty branches.

[0011] This invention also proposes a controllable surge-protected energy-saving management method, comprising the following steps: S10 monitors the status parameters of the energy storage battery cluster and the electrical parameters of each frequency converter branch connected to the DC bus, and determines whether it is necessary to close or open the frequency converter branch. S20, when it is necessary to close or open the frequency converter branch, the bypass switch in the surge protection control module is opened, so that the parallel surge suppression branch is connected to the main circuit; S30, performs the contactor closing or opening operation of the frequency converter branch, and uses the surge suppression branch to absorb the surge energy generated at the moment of switching. S40: After the contactor in the frequency converter branch completes its operation, the bypass switch is closed to bypass the surge suppression branch and restore the main circuit to a low impedance state.

[0012] Furthermore, the specific steps for branch closure include: When the voltage difference between the DC bus voltage VTi of the i-th branch and the real-time voltage Vbat of the energy storage battery cluster is less than or equal to a preset threshold. First disconnect the bypass switch, then close the contactor of the i-th branch; After a delay, wait for the surge suppression branch to complete soft start and surge absorption before closing the bypass switch.

[0013] Furthermore, the specific steps for branch disconnection include: When the total voltage, individual cell voltage, or temperature of the energy storage battery cluster exceeds the safety threshold, or the current of the kth branch exceeds the overcurrent threshold, a disconnect command is generated. First disconnect the bypass switch, then disconnect the corresponding branch contactor; After the surge suppression branch absorbs the inductor energy stored at the moment of disconnection, the bypass switch is closed to allow other normal branches to continue working.

[0014] The present invention also proposes an elevator, including a controllable surge-proof energy-saving management system, wherein its DC bus terminal is electrically connected to the DC bus, and its energy storage battery cluster is used to absorb regenerative energy when the elevator is in braking mode and to release electrical energy to provide auxiliary power to the elevator when the elevator is in electric mode.

[0015] This invention employs a time-division multiplexing control strategy to limit inrush current to below 50A during switching transients using MOSFET soft-start, eliminating the risks of voltage sag and contact welding. During steady-state operation, it closes the bypass switch to achieve micro-ohm-level shoot-through, completely eliminating conduction losses. This solution not only resolves the inherent contradiction between surge suppression and low loss but also suppresses voltage spikes when a faulty branch is disconnected through soft-severance technology, preventing the propagation of single-point faults and significantly improving system reliability, safety, and electrical lifespan. Attached Figure Description

[0016] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the module structure of the controllable surge-proof energy-saving management system of the present invention; Figure 2 This is a schematic diagram of the topology of the controllable surge-protected energy-saving management system of the present invention; Figure 3 This is a flowchart illustrating the controllable surge-protected energy-saving management method of the present invention; Figure 4 This is a schematic diagram illustrating an example of energy-saving mode control in the controllable surge-proof energy-saving management method of the present invention.

[0019] The objectives, features, and advantages of this invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0020] It should be understood that the specific embodiments described herein are merely illustrative of the technical solutions of the present invention and are not intended to limit the present invention.

[0021] To better understand the technical solution of the present invention, a detailed description will be provided below in conjunction with the accompanying drawings and specific embodiments.

[0022] like Figure 1 As shown, Figure 1 This is a schematic diagram of the module structure of the controllable surge protection energy-saving management system of the present invention.

[0023] Reference Figure 1 This invention proposes a controllable surge-protected energy-saving management system, comprising: DC bus, used to connect DC bus branches of multiple frequency converters; Energy storage battery clusters are used to store and release electrical energy; The circuit protection unit is connected between the energy storage battery cluster and multiple DC bus branches of multiple external frequency converters to realize independent on / off control and overcurrent protection of the DC bus branches; A surge protection control module is connected in the main circuit between the energy storage battery cluster and the circuit protection unit; the surge protection control module includes a surge suppression branch and a bypass switch connected in parallel; the surge suppression branch is composed of a power switch and its driving circuit, and is used to suppress surge voltage and surge current during the transient process of the branch being turned on or off; An energy-saving management unit is connected to the energy storage battery cluster, the surge protection control module, and the circuit protection unit, respectively. The energy-saving management unit is configured to: disconnect the bypass switch before controlling any branch contactor in the circuit protection unit to perform a closing or opening operation, so as to put the surge suppression branch into operation; after the transient process ends, close the bypass switch to bypass the surge suppression branch, so as to reduce the loss during steady-state operation of the system.

[0024] like Figure 2 As shown, Figure 2 This is a schematic diagram of the topology of the controllable surge protection energy-saving management system of the present invention.

[0025] Reference Figure 2 The controllable surge-protected energy-saving management system of the present invention is mainly composed of three parts in its overall topology: the energy-saving management system area, the DC common bus area, and the external frequency converter area.

[0026] Energy-saving management system area: including energy storage battery clusters, surge protection control modules, loop protection units and energy-saving management units, which is the core control and energy storage part of the system.

[0027] DC common bus area: Composed of DC bus positive and negative busbars, serving as a common channel for energy exchange between the energy storage battery cluster and each elevator inverter.

[0028] External frequency converter equipment area: includes N elevator traction machine frequency converters and their loads (traction machine M), and the DC side of each frequency converter is connected to the DC common bus through an independent branch.

[0029] The connection is as follows: the positive and negative terminals (DC+, DC-) of the energy storage battery cluster are connected to the DC common bus positive and negative busbars after passing through the surge protection control module; the positive and negative terminals of the DC side of each elevator frequency converter are connected to the DC common busbars through independent circuit protection branches (contactors, fuses, circuit breakers, etc.); the energy management unit is connected to the energy storage battery cluster, surge protection module, circuit protection unit and each frequency converter through control signal lines and communication lines respectively to realize global monitoring and coordinated control.

[0030] Furthermore, the energy storage battery cluster is composed of multiple individual battery cells connected in series. In this embodiment, 100 series lithium iron phosphate batteries are used, with a rated total voltage of 320V, a rated capacity of 10Ah, and support for 3C (30A) charging and discharging. The battery cluster has a built-in BMS (Battery Management System) that communicates with the energy-saving management unit via a CAN bus, reporting operating parameters such as total voltage, individual cell voltage, SOC, SOH, temperature, and fault status in real time. The positive and negative output terminals of the battery cluster are connected to the input terminal of the surge protection control module after passing through the main fuse.

[0031] Furthermore, the surge protection control module is connected in series between the energy storage battery cluster and the DC common bus, and its internal structure is as follows: Figure 2 As shown, it mainly includes the following components: Power switch (Q1): Model IXFH50N60P. Its drain (D) is connected to the positive terminal (DC+) of the energy storage battery cluster, and its source (S) is connected to one end of the bypass switch (PK) and the input terminal of the circuit protection unit. It is used to suppress surge current during switching transients.

[0032] RC soft-start circuit (C1): Connected between the gate (G) and source (S) of the power switch. In this embodiment, C1 = 2.2μF. It is used to control the conduction rate of the power switch to achieve soft start and limit the surge current to below 50A.

[0033] The voltage divider resistor network (R1, R2): R1=3.9kΩ, R2=100kΩ, is connected between the positive terminal of the energy storage battery cluster and the gate of the power switch to provide a steady-state -12V operating voltage to the gate and ensure reliable conduction of the power switch.

[0034] Zener diode (D1): Zener voltage is 18V. It is connected in parallel between the gate and source of the power switch to clamp the gate-source voltage and prevent overvoltage damage to the power device.

[0035] Bypass switch (PK): A DC 500V, 50A DC contactor is used, connected in parallel with the power switching tube branch. During steady-state operation of the system, the bypass switch closes to bypass the surge suppression branch and eliminate its conduction losses; during branch switching operations, the bypass switch opens, allowing the surge suppression branch to operate.

[0036] Surge protector (SPD): It adopts a varistor design, with a maximum continuous operating voltage Uc=385VDC and a voltage protection level Up≤1.2kV. It is connected in parallel between the positive and negative terminals of the DC bus to discharge transient surge voltage and protect system equipment.

[0037] In this embodiment, the circuit protection unit configures an independent branch for each elevator inverter, and the structure of each branch is as follows: Figure 2 As shown, it mainly includes: Branch contactors (K1, K2...Kn): used to control the on / off state of the corresponding branch, realizing independent control function of multiple branches.

[0038] Fuse (F1, F2...Fn): Connected in series in the branch circuit to provide overcurrent and short-circuit protection for the branch circuit.

[0039] Current detection unit: connected in series in the branch circuit, used to collect the branch circuit current in real time, providing the energy management unit with the basis for overcurrent judgment.

[0040] The input terminals of all branches converge and are connected to the output terminal of the surge protection control module; the output terminals of all branches are respectively connected to the positive and negative terminals of the DC side of the corresponding elevator frequency converter.

[0041] In this embodiment, the energy-saving management unit adopts an industrial-grade ARM controller, which has multiple analog inputs (AI), digital inputs / outputs (DI / DO), and a CAN communication interface. It collects analog quantities such as branch current, DC bus voltage, and total battery cluster voltage through AI; controls the opening and closing of bypass switches (PK) and branch contactors (K1~Kn) through DO; and interacts with the battery cluster BMS and each inverter through CAN communication for data exchange and fault diagnosis, thereby achieving intelligent management of the entire system.

[0042] This embodiment uses an energy-saving system with a 320V rated voltage energy storage battery cluster and multiple elevator inverters sharing a DC bus as the application scenario. It describes in detail the specific implementation process, hardware selection calculation, and parameter matching of the controllable surge protection energy management method. This method is applicable to energy recovery scenarios of electromechanical equipment with inverter DC buses, such as elevators, lifts, and oil pumps. The core is to achieve the dual technical goals of transient surge suppression and steady-state low loss by time-sharing the surge protection module.

[0043] The implementation of this method is based on a pre-configured surge protection control module. Its core components have all been precisely selected and their parameters calculated to be compatible with energy storage and energy-saving systems with a system voltage of 320V and a rated operating current of 30A. The specific selection and calculation are as follows: The selection and parameter calculation of the power switch are as follows: As the core power device in the surge suppression branch, the selection must take into account voltage withstand capability, current carrying capacity, low conduction loss, and drive compatibility. The key parameter calculation and selection results are as follows: Breakdown voltage Vds: The system rated DC voltage is 320V. Considering a 30% margin for surge and voltage fluctuation, the calculated value is 320V×1.3=416V. A standard voltage withstand rating of 600V is selected to meet the voltage withstand redundancy requirements; Rated current Id: The system continuous operating current is 30A. Considering a 1.5 times overload capacity, the calculated value is 30A. ×1.5=45A, select a device with Id≥50A@25℃; On-resistance Rds(on): To control conduction loss, the voltage drop under 50A current is required to be less than 2% of the system voltage, i.e. 320V×0.02=6.4V. The maximum allowable Rds(on) is calculated to be 6.4V / 30A=0.213Ω, so select a device with Rds(on)<0.2Ω@Vgs=-10V; Gate charge Qg: To adapt to the RC drive circuit, select a medium Qg value of 50-150nC to ensure switching speed and drive stability. Ultimately, the IXFH50N60P (IXYS) was selected, with key parameters: Vdss=-600V, Id=-50A@25℃, Rds(on)=0.15Ω@Vgs=-10V, Tj=25℃, Qg=110nC (typical value), Vgs(th)=-2V~-4V, and a TO-247 package, which perfectly matches the above calculation requirements.

[0044] The RC network includes a voltage divider resistor network (R1, R2) and a soft-start capacitor C1, used to provide a steady-state gate voltage for the power switch and control the conduction rate to achieve soft start. The design requirements for this embodiment are: soft-start time t_soft = 20ms, surge current I_inrush < 50A, and steady-state gate voltage Vgs = -12V. The voltage divider resistors R1 and R2 are calculated as follows: In steady state, the source voltage Vs = 320V, Vgs = -12V, therefore the gate voltage Vg = Vs - |Vgs| = 308V. According to the voltage divider relationship Vg = Vs × R2 / (R1 + R2), assuming R2 = 100kΩ (standard value, low power consumption), we get R1 = (320V × 100kΩ / 308V) - 100kΩ ≈ 3.9kΩ.

[0045] The calculation method for the soft-start capacitor C1 is as follows: Gate equivalent resistance R_eq = R1∥R2 ≈ 3.75kΩ. For the RC charging circuit, the time to reach 95% voltage is 3τ (τ is a time constant). Let 3τ = 20ms, then τ = 6.67ms. From τ = R_eq × C1, we get C1 = 6.67ms / 3.75kΩ ≈ 1.78μF, and the standard value of 2.2μF is selected.

[0046] Soft start time verification: Actual τ = 3.75kΩ × 2.2μF = 8.25ms, actual soft start time ≈ 3τ = 24.75ms, which meets the design requirement of 20-30ms.

[0047] Power and voltage rating matching: R1 power consumption P_R1=(Vs-Vg)² / R1=(12V)² / 3.9kΩ=0.037W, select a 1 / 4W resistor; R2 power consumption P_R2=Vg² / R2=(308V)² / 100kΩ=0.95W, select a 1W resistor; C1 voltage rating ≥1.5×Vs=480V, select a 630VDC film capacitor.

[0048] The Zener diode is used to clamp the gate-source voltage of the power switch to prevent overvoltage damage. In this embodiment, the gate-source withstand voltage of the power switch is ±20V~±30V, so a Zener diode with a Zener voltage of 18V@Izt=5mA and a maximum power of 1W, packaged in DO-41, is selected. Its connection method is as follows: the cathode is connected to the source of the power switch, and the anode is connected to the gate, to achieve gate-source voltage overvoltage clamping protection.

[0049] The surge protector (SPD) provides passive surge voltage discharge capability for the system and is suitable for transient surge protection of DC bus. Maximum continuous operating voltage Uc: Uc≥1.2×320V=384V, standard value 385VDC is selected. Voltage protection level Up: Up≤inverter withstand voltage (typically 500-800V), Up≤1.2kV@20kA is selected. Discharge current: Nominal discharge current In≥20kA (8 / 20μs), maximum discharge current Imax=40kA. Other characteristics: Response time <25ns, built-in thermal trip and fault indication, 35mm DIN rail mounting, suitable for industrial site layouts.

[0050] The bypass contactor (PK) is used to bypass the surge suppression branch in steady state, eliminating conduction losses. Voltage rating: The system voltage is 320VDC. Considering a 1.5 times overload, 320V × 1.5 = 480V, a DC 500V or DC 750V platform DC contactor is selected. Current rating: The system rated current is 30A. Considering a 1.5 times overload, 30A × 1.5 = 45A, a 50A or higher current platform is selected. Control parameters: The control coil voltage is selected as DC 24V, compatible with the standard voltage of industrial control systems.

[0051] like Figure 3 As shown, Figure 3 This is a flowchart illustrating the controllable surge protection energy-saving management method of the present invention.

[0052] Reference Figure 3 The present invention also proposes a controllable surge-protected energy-saving management method, comprising the following steps: S10 monitors the status parameters of the energy storage battery cluster and the electrical parameters of each frequency converter branch connected to the DC bus, and determines whether it is necessary to close or open the frequency converter branch. S20, when it is necessary to close or open the frequency converter branch, the bypass switch in the surge protection control module is opened, so that the parallel surge suppression branch is connected to the main circuit; S30, perform the contactor closing or opening operation of the frequency converter branch, and use the surge suppression branch to absorb the surge energy generated at the moment of switching; S40, after the contactor of the frequency converter branch completes its operation, the bypass switch is controlled to close, bypassing the surge suppression branch and restoring the main circuit to a low impedance state.

[0053] like Figure 4 , Figure 4 This is a schematic diagram illustrating an example of energy-saving mode control in the controllable surge-proof energy-saving management method of the present invention.

[0054] In this embodiment, S10, monitoring the status parameters of the energy storage battery cluster and the electrical parameters of each frequency converter branch connected to the DC bus, and determining whether it is necessary to close or open the frequency converter branch, includes the following steps: S11, System Power-On Self-Test: After the system is powered on, the energy-saving management unit first executes the power-on self-test procedure to comprehensively test the status of the energy storage battery cluster, surge protection module, and circuit protection unit.

[0055] If S12 detects any fault (such as battery cell overvoltage, abnormal temperature, contactor sticking, etc.), it will immediately perform protection actions, disconnect all DC contactors, cut off the main circuit, and report the fault information; if there is no fault, the system will enter standby mode and monitor various operating parameters in real time.

[0056] In this embodiment, the real-time status monitoring energy-saving management unit continuously monitors the following parameters via CAN communication and analog signal acquisition: Energy storage battery cluster: total voltage Vbat, individual cell voltage Vcell, cell temperature Tbat, branch current, etc. DC bus: DC side voltage VTi and branch current Ik of each elevator branch. Contactor status: open / closed status of each branch contactor (K1~Kn) and bypass contactor (PK). The contactor status is automatically identified through auxiliary contacts or voltage / current detection.

[0057] The branch closure condition is determined based on the voltage difference between the actual voltage VTi on the monitored DC bus and the real-time voltage Vbat of the energy storage battery cluster. Specifically, when |VTi-Vbat|≤λ, i represents any one of the internal frequency converters, VTi is the branch voltage implemented by the i-th frequency converter, Vd is the real-time voltage of the energy storage battery cluster, and λ is the preset loop closure voltage difference coefficient. In this embodiment, λ=10. The overcurrent condition refers to the current Ik on the DC branch of each frequency converter being ≤Ithk-β, where Ithk is the overcurrent fault threshold of the k-th frequency converter, and β is the overcurrent dead zone coefficient. In this embodiment, β=1.5.

[0058] In this embodiment, S20, when it is necessary to close or open the frequency converter branch, controlling the bypass switch in the surge protection control module to open, so that the parallel surge suppression branch is connected to the main circuit includes: When the system needs to connect the i-th elevator frequency converter to the energy storage system for energy recovery, the following steps are performed: S21, Closure Condition Judgment: The energy-saving management unit determines in real time whether the branch closure condition is met: Battery cluster status is normal: total voltage Vbat∈[280V,360V], individual cell voltage Vcell∈[2.8V,3.6V], temperature Tbat∈[25℃,40℃]. Voltage difference satisfies: the voltage difference |VTi-Vbat| between the DC side voltage VTi of the i-th elevator inverter and the battery cluster voltage Vbat ≤ 10V (preset closure threshold). When all the above conditions are met, a closure command is generated.

[0059] S22, the surge suppression branch energy-saving management unit sends a control signal to the surge protection control module, disconnecting the bypass contactor PK, and putting the surge suppression branch (power switch Q1) into the main circuit. At this time, the RC soft-start circuit, composed of equivalent resistors R1 and R2 and capacitor C1, is used to control the conduction rate of Q1. The soft-start time is approximately 25ms, limiting the surge current to below 50A.

[0060] S23, the closed-circuit contactor energy-saving management unit sends a signal to the circuit protection unit to close the contactor Ki of the i-th branch. At this time, the surge suppression branch absorbs the surge energy generated at the moment of switching, effectively suppressing surge voltage and surge current, and protecting the contactor contacts and power devices.

[0061] S24, after a delay of T seconds (first preset time, such as 200ms) to restore steady-state operation, the energy-saving management unit sends a signal to close the bypass contactor PK after the transient process ends, bypassing the surge suppression branch, and the system resumes low-impedance steady-state operation, eliminating the conduction loss of the power switching transistor.

[0062] In this embodiment, S30, the contactor of the frequency converter branch is closed or opened, and the surge suppression branch absorbs the surge energy generated during switching, including: In this embodiment, the branch disconnection operation is divided into the following two cases according to different triggering conditions: Battery cluster fault disconnection: When the operating parameters of the energy storage battery cluster are detected to exceed the preset fault threshold (such as total voltage Vbat < 280V or > 360V, single cell voltage Vcell < 2.8V or > 3.6V, temperature Tbat < 25℃ or > 40℃), the following steps are executed: S31a, the energy-saving management unit generates a disconnect command, first disconnecting the bypass contactor PK and then engaging the surge suppression branch.

[0063] S32a controls the disconnection of all branch contactors (K1~Kn), cutting off the connection between the energy storage battery pack and all elevator frequency converters.

[0064] S33a, after a second preset time delay, close the bypass contactor PK, and the system enters a safe standby state.

[0065] This embodiment sets a relatively strict temperature window (25℃-40℃) for specific application scenarios to ensure optimal performance. In actual applications, the threshold can be adjusted according to battery characteristics.

[0066] When the current Ik of the kth DC bus branch exceeds the preset overcurrent fault threshold (e.g., Ik > Y × 30A, where Y is the overcurrent setting coefficient, taken as 1.5), the following steps are executed: S31b, the energy-saving management unit generates an emergency disconnect command, first disconnecting the bypass contactor PK and engaging the surge suppression branch.

[0067] S32b controls the disconnection of contactor Kk of the kth branch, isolating the faulty branch from the system.

[0068] S33b, after a third preset time delay, closes the bypass contactor PK to restore the system to steady-state operation. During this process, other unfaulty branches remain connected to ensure that the overall system operation is not affected by a single point of failure.

[0069] Where k is the sequence number of the DC bus branch whose current Ik exceeds the preset overcurrent fault threshold.

[0070] In this embodiment, S40, after the contactor of the frequency converter branch completes its operation, the bypass switch is then controlled to close, bypassing the surge suppression branch and restoring the main circuit to a low impedance state. Specifically, this involves: In this embodiment, during normal system operation, the bypass contactor PK is always in a closed state to bypass the surge protection module, thereby reducing the conduction loss during steady-state operation of the system.

[0071] Meanwhile, the system has the following real-time protection functions: Passive surge voltage discharge: The surge protector (SPD) connected in parallel between the DC bus is a passive device, using a varistor design; when a surge voltage exceeds its discharge threshold (Uc=385VDC), it can discharge the surge voltage within microseconds, limiting the voltage protection level to Up≤1.2kV, protecting the system equipment. Active predictive protection: The energy-saving management unit monitors the voltage and current on the DC side of each inverter in real time, predicts that the system is about to reach the fault threshold point, and actively executes protection actions. Before the branch contactor operates, the bypass relay is first disconnected, and the power switch is slowly turned on, allowing the surge protection module to be put into the system first, effectively suppressing the surge current; after the branch contactor closes or opens, the bypass contactor is closed after a delay, ensuring that the system safely and smoothly transitions to a steady state.

[0072] The above description is only a part of the embodiments of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made under the technical concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A controllable surge-protected energy-saving management system, characterized in that, include: DC bus, used to connect DC bus branches of multiple frequency converters; Energy storage battery clusters are used to store and release electrical energy; A circuit protection unit is connected in series between the energy storage battery cluster and the DC bus to control the disconnection of the energy storage battery cluster from the DC bus branch when a branch fault occurs or when disconnection is required according to the energy-saving management strategy. A surge protection control module is connected in the main circuit between the energy storage battery cluster and the circuit protection unit; An energy-saving management unit is connected to the energy storage battery cluster, the surge protection control module, and the circuit protection unit, respectively. The energy-saving management unit is configured to: control the surge protection control module to enter surge suppression mode before controlling any branch contactor in the circuit protection unit to perform a closing or opening operation; and control the surge protection control module to enter low-loss mode after the transient process ends.

2. The controllable surge protection energy-saving management system according to claim 1, characterized in that, The surge control module includes a surge suppression branch and a bypass switch connected in parallel. The surge suppression branch includes a power switch and its driving circuit, used to suppress surge voltage and surge current during the transient process of the branch being turned on or off; wherein, the drain of the power switch is connected to the positive terminal of the energy storage battery cluster, and its source is connected to one end of the bypass switch and the circuit protection unit. The energy-saving management unit is also configured to: disconnect the bypass switch when the surge control module enters the surge suppression mode, so that the surge suppression branch is put into operation; and close the bypass switch when the surge control module enters the low-loss mode, so as to bypass the surge suppression branch and reduce the loss during steady-state operation of the system.

3. The controllable surge-protected energy-saving management system according to claim 2, characterized in that, The surge suppression branch also includes: An RC soft-start circuit is connected between the gate and source of the power switch to control the conduction rate of the power switch and achieve soft start. A voltage divider resistor network is connected between the positive terminal of the energy storage battery cluster and the gate of the power switch to provide a steady-state operating voltage for the gate. A Zener diode is connected in parallel between the gate and source of the power switch to clamp the gate-source voltage and protect the MOSFET.

4. The controllable surge protection energy-saving management system according to claim 1, characterized in that, The energy-saving management unit is also configured to: Real-time acquisition of the operating parameters of the energy storage battery cluster, including total voltage, individual cell voltage, temperature and branch current; Real-time acquisition of voltage and current of each DC bus branch; When the voltage difference |VTi-Vbat| between the DC bus voltage VTi of the i-th branch and the real-time voltage Vbat of the energy storage battery cluster is less than or equal to a preset closing threshold, a closing command is generated and output to the surge protection control module, so that the surge protection control module responds to the closing command, disconnects the bypass switch, and then sends a signal to the circuit protection unit to close the corresponding branch contactor. After a first preset time delay, a signal is sent again to close the bypass switch.

5. The controllable surge-protected energy-saving management system according to claim 1, characterized in that, The energy-saving management unit is also configured to: When the operating parameters of the energy storage battery cluster are detected to exceed the preset fault threshold, a disconnect command is generated and output to the surge protection control module to send a signal so that the surge protection control module responds to the disconnect command and disconnects the bypass switch; then a signal is sent to the circuit protection unit to disconnect the corresponding branch contactor, and after a second preset time delay, a signal is sent again to close the bypass switch.

6. The controllable surge-protected energy-saving management system according to claim 1, characterized in that, The energy-saving management unit is also configured to: When the current Ik of the kth DC bus branch is detected to exceed the preset overcurrent fault threshold, an emergency disconnect command is generated; and a signal is sent to the surge protection control module to make the surge protection control module respond to the emergency disconnect command and disconnect the bypass switch; then a signal is sent to the circuit protection unit to disconnect the branch contactor corresponding to the kth branch, and after a third preset time delay, a signal is sent to close the bypass switch, while maintaining the connection status of other non-faulty branches.

7. A controllable surge-protected energy-saving management method, characterized in that, The method is applied to the controllable surge-protected energy-saving management system as described in any one of claims 1 to 6, characterized in that the controllable surge-protected energy-saving management system includes a DC bus, an energy storage battery cluster, a circuit protection unit, a surge protection control module, and an energy-saving management unit, and the method includes the following steps: S10 monitors the status parameters of the energy storage battery cluster and the electrical parameters of each frequency converter branch connected to the DC bus, and determines whether it is necessary to close or open the frequency converter branch. S20, when it is necessary to close or open the frequency converter branch, the bypass switch in the surge protection control module is opened, so that the parallel surge suppression branch is connected to the main circuit; S30, perform the contactor closing or opening operation of the frequency converter branch, and use the surge suppression branch to absorb the surge energy generated at the moment of switching; S40, after the contactor of the frequency converter branch completes its operation, the bypass switch is controlled to close, bypassing the surge suppression branch and restoring the main circuit to a low impedance state.

8. The controllable surge-protected energy-saving management method according to claim 7, characterized in that, The specific steps of the branch closure operation include: When the voltage difference between the DC bus voltage VTi of the i-th branch and the real-time voltage Vbat of the energy storage battery cluster is less than or equal to a preset threshold. First disconnect the bypass switch, then close the contactor of the i-th branch; After a delay, wait for the surge suppression branch to complete soft start and surge absorption before closing the bypass switch.

9. The controllable surge-protected energy-saving management method according to claim 7, characterized in that, The specific steps of the branch disconnection operation include: When the total voltage, individual cell voltage, or temperature of the energy storage battery cluster exceeds the safety threshold, or the current of the kth branch exceeds the overcurrent threshold, a disconnect command is generated. First disconnect the bypass switch, then disconnect the corresponding branch contactor; After the surge suppression branch absorbs the inductor energy stored at the moment of disconnection, the bypass switch is closed to allow other normal branches to continue working.

10. An elevator, characterized in that, The system includes a controllable surge-protected energy-saving management system as described in any one of claims 1 to 6, wherein its DC bus terminal is electrically connected to the DC bus, and its energy storage battery cluster is used to absorb regenerative energy when the elevator is in braking mode and to release electrical energy to provide auxiliary power to the elevator when the elevator is in electric mode.

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