Pre-charging current limiting and safety protection system for high-voltage box

Abstract

The invention discloses a pre-charging current limiting and safety protection system for a high-voltage box, relates to a high-voltage box protection device, and aims to solve the problems of low safety and poor adaptability caused by the fact that an existing high-voltage box protection system cannot monitor sudden faults in real time and lacks a current limiting strategy. The main contactor is used for connecting or disconnecting a main loop between a high-voltage source and a high-voltage load; the solid-state pre-charging diagnosis module is used for executing pre-charging and fault diagnosis when the main contactor is in an off state; the high-voltage box control unit is used for controlling the cooperative work of the main contactor and the solid-state pre-charging diagnosis module; the high-voltage box control unit is configured as follows: before the main contactor is switched on, pre-fault diagnosis is started; if the diagnosis result is a healthy state, the high-voltage source is instructed to execute self-adaptive current-limiting pre-charging and state monitoring in charging; and after the pre-charging completion signal is received, the main contactor is controlled to be switched on, and the pre-charging process of the high-voltage box is completed. The method has the beneficial effect that the adaptability of the pre-charging process is improved.

Description

Technical Field

[0001] This invention relates to a high-voltage box protection device. Background Technology

[0002] In high-voltage power supply systems, such as electric vehicles, energy storage power stations, or industrial frequency converters, the high-voltage load side typically contains large-capacity capacitors. To prevent the huge surge current generated by capacitor charging at the moment the main contactor closes from impacting the contactor contacts and load, a pre-charging circuit is usually required to perform current-limited charging of the load capacitor before the main contactor closes.

[0003] Existing pre-charging technologies often employ a current-limiting resistor connected in parallel with the main contactor. However, once the resistance value of this current-limiting resistor is determined, it cannot be changed. This fixed current-limiting method cannot adjust the charging current according to the actual state of the high-voltage load (such as a capacitor), especially its equivalent series resistance or thermal tolerance. This can lead to inappropriate charging current in some cases, posing a risk of overheating the load, or failing to achieve the optimal charging rate, thus lacking adaptability.

[0004] Furthermore, existing pre-charge circuits lack the ability to diagnose circuit conditions before initiating charging. The system cannot know in advance whether a short circuit fault exists at the high-voltage load end or whether the main contactor has become welded together. Initiating pre-charge under these abnormal conditions will cause serious impact or safety hazards to the system, lacking safety guarantees before startup.

[0005] Furthermore, existing current-limiting resistor solutions cannot dynamically monitor the status of high-voltage loads in real time during the pre-charging process. If the load experiences internal breakdown or a sudden change in characteristics during charging, the system will not be able to detect and respond in time, and will continue to execute the pre-charging process, leading to the expansion of the fault and ultimately causing the main contactor to close on a failed load, lacking dynamic protection capabilities during the process. Summary of the Invention

[0006] The purpose of this invention is to solve the problems of low safety and poor adaptability caused by the inability of existing high-voltage box protection systems to monitor sudden faults in real time and the lack of current limiting strategies. A high-voltage box pre-charge current limiting and safety protection system is proposed.

[0007] The high-voltage box pre-charge current limiting and safety protection system of the present invention includes a main contactor, a solid-state pre-charge diagnostic module and a high-voltage box control unit; The main contactor is used to connect or disconnect the main circuit between the high-voltage source and the high-voltage load. A solid-state precharge diagnostic module, connected in parallel with the main contactor, is used to perform precharge and fault diagnosis when the main contactor is open. A high-voltage box control unit is used to control the coordinated operation of the main contactor and the solid-state pre-charge diagnostic module; wherein, the high-voltage box control unit is configured as follows: Before the main contactor is turned on, the solid-state pre-charge diagnostic module is instructed to perform pre-start fault diagnosis; if the diagnosis result is a healthy state, the high-voltage source is instructed to perform adaptive current-limiting pre-charging and charging status monitoring; after receiving the pre-charging completion signal, the main contactor is controlled to turn on to complete the high-voltage box pre-charging process.

[0008] Furthermore, the solid-state precharge diagnostic module includes: Power topology unit for injecting diagnostic signals and performing adaptive current-limiting pre-charge; Sensing and acquisition unit, used to acquire voltage and current data sequences; The local control unit is used to control the power topology unit and process the collected data, and perform pre-start fault diagnosis, adaptive current limiting pre-charging and charging status monitoring. The fault feature library storage unit is used to store comparison benchmark data for fault diagnosis before startup.

[0009] Furthermore, the local control unit is configured to perform the pre-startup fault diagnosis, specifically including: The power topology unit is controlled to inject a high-frequency detection signal into the high-voltage load; Based on the instantaneous voltage data sequence and the instantaneous current data sequence acquired by the sensing and acquisition unit, the complex voltage component and the complex current component at the frequency of the high-frequency detection signal are extracted by frequency domain transformation, and the ratio of the complex voltage component to the complex current component is calculated to obtain the complex impedance characteristics of the high-voltage load, and the actual capacitance value and the actual equivalent series resistance are quantitatively estimated. The complex impedance characteristics, the actual capacitance value, and the actual equivalent series resistance are compared with the comparison benchmark data pre-stored in the fault feature library storage unit to determine whether the high-voltage load has a short-circuit fault and whether the main contactor has a welding fault.

[0010] Furthermore, the local control unit is also configured to perform the adaptive current-limiting pre-charge, specifically including: When the pre-start fault diagnosis results are in a healthy state, the preset maximum capacitor heating power threshold is retrieved. Based on the maximum heating power threshold of the capacitor and the quantified actual equivalent series resistance, the upper limit of the current is calculated, and then the target charging current value required for the adaptive current limiting pre-charging is set.

[0011] Furthermore, the local control unit is configured to perform the adaptive current-limiting precharge, including: The power topology unit is configured to operate in switching converter mode, and the target charging current value is used as the set value. The actual charging current fed back by the sensing and acquisition unit is used as the feedback value. A closed-loop constant current control algorithm is executed to complete the adaptive current limiting pre-charging.

[0012] Furthermore, the local control unit, in order to perform the charging status monitoring, is configured to obtain the dynamic complex impedance during the charging process in real time, specifically including: During the same period of performing the adaptive current-limiting pre-charging, the voltage ripple component and the current ripple component are extracted from the instantaneous voltage data sequence and the instantaneous current data sequence collected by the sensing and acquisition unit using the inherent switching frequency of the power topology unit when operating in the switching converter mode; and the dynamic complex impedance during the charging process is obtained in real time by calculating the ratio of the voltage ripple component to the current ripple component.

[0013] Furthermore, the local control unit is also configured to: The real-time obtained dynamic complex impedance is continuously compared with the reference complex impedance; when a sudden characteristic deviation of the dynamic complex impedance is detected, it is determined that the high-voltage load has an internal breakdown or short circuit fault during the charging process, and the adaptive current limiting pre-charging is immediately stopped to perform instantaneous protection action.

[0014] Furthermore, the reference complex impedance is a theoretical reference complex impedance calculated based on the actual capacitance value and the actual equivalent series resistance obtained by quantification during the pre-start fault diagnosis stage, and for the current switching frequency of the power topology unit.

[0015] Furthermore, the local control unit is also configured to: Based on the target charging current value and the actual capacitance value, the expected charging voltage slope is obtained and stored by calculating the ratio of the target charging current value to the actual capacitance value. During the same period of performing the adaptive current limiting pre-charging, the actual charging voltage at the high-voltage load end is continuously monitored. The rate of change of the actual charging voltage is compared with the expected charging voltage slope, and when the rate of change of the actual charging voltage deviates from the expected charging voltage slope, it is used to determine that the high-voltage load is abnormal.

[0016] Furthermore, the local control unit is also configured to: After determining that the high-voltage load has failed during charging and stopping the adaptive current-limiting pre-charging, the system immediately reports diagnostic status information to the high-voltage box control unit. The diagnostic status information is used to indicate that the charging status monitoring has identified a fault.

[0017] Compared with the prior art, the present invention has the following advantages: This invention injects a high-frequency detection signal before startup and compares the calculated complex impedance characteristics with a pre-stored benchmark. This allows for the identification of serious faults such as short circuits at the high-voltage load end or welding of the main contactor before the pre-charging process begins, preventing the system from being forcibly started under fault conditions and improving the initial safety of equipment operation.

[0018] This invention achieves dynamic monitoring of the load state during charging by using the switching ripple to calculate the dynamic complex impedance in real time during the pre-charging process and continuously comparing it with the reference complex impedance. It can quickly respond to sudden faults such as internal breakdown at the high-voltage load end and immediately stop charging to perform protection, thus preventing the fault from escalating further.

[0019] This invention achieves adaptive current limiting by calculating and setting the target charging current value based on the actual equivalent series resistance obtained from pre-start diagnosis and combined with the preset maximum heat generation power threshold of the capacitor. This breaks away from the limitations of traditional fixed current limiting values, making the setting of the charging current more closely match the actual heat bearing capacity of the load. Through closed-loop control, it is precisely executed, improving the adaptability of the pre-charging process while ensuring pre-charging safety. Attached Figure Description

[0020] Figure 1 This is a block diagram of the overall structure of a high-voltage box pre-charging current limiting and safety protection system as described in Specific Implementation Method 1; Figure 2 This is a schematic diagram of the overall workflow of a high-voltage box pre-charging current limiting and safety protection system in Specific Implementation Method 1; Figure 3 This is a functional block diagram of the solid-state pre-charge diagnostic module in the second specific implementation method. Detailed Implementation

[0021] Specific Implementation Method 1: Combination Figures 1 to 2 This embodiment describes a high-voltage box pre-charge current limiting and safety protection system, which includes a main contactor 1, a solid-state pre-charge diagnostic module 2, and a high-voltage box control unit 3. Main contactor 1 is used to connect or disconnect the main circuit between high voltage source 4 and high voltage load 5; Solid-state precharge diagnostic module 2 is connected in parallel with the main contactor 1 and is used to perform precharge and fault diagnosis when the main contactor 1 is disconnected; The high-voltage box control unit 3 is used to control the coordinated operation of the main contactor 1 and the solid-state pre-charge diagnostic module 2; wherein, the high-voltage box control unit 3 is configured as follows: Before the main contactor 1 is turned on, the solid-state pre-charge diagnostic module 2 is instructed to perform pre-start fault diagnosis; if the diagnosis result is a healthy state, the high-voltage source 4 is instructed to perform adaptive current limiting pre-charging and charging status monitoring; after receiving the pre-charging completion signal, the main contactor 1 is controlled to turn on to complete the high-voltage box pre-charging process.

[0022] In this embodiment, the high-voltage source 4 is a high-voltage battery pack, DC power supply, or fuel cell stack; the high-voltage load 5 is an inverter, converter, or other high-voltage equipment, and the high-voltage load 5 typically has a bus capacitor inside. The main contactor 1 is located in the main circuit between the high-voltage source 4 and the high-voltage load 5, and is used to connect or disconnect the main circuit. The solid-state pre-charge diagnostic module 2 is electrically connected in parallel with the main contactor 1; the solid-state pre-charge diagnostic module 2 is used to perform pre-charging of the high-voltage load 5 when the main contactor 1 is disconnected, and to perform fault diagnosis on the high-voltage load 5 or the main contactor 1 before or during pre-charging. The high-voltage box control unit 3 establishes signal communication with both the solid-state pre-charge diagnostic module 2 and the main contactor 1. The high-voltage box control unit 3 is used to send control commands to the solid-state pre-charge diagnostic module 2 and receive diagnostic status information reported by the solid-state pre-charge diagnostic module 2; the high-voltage box control unit 3 is also used to control the closing and opening of the main contactor 1. The high-voltage box control unit 3 can be a functional module of the vehicle controller, a functional module of the battery management system, or a dedicated high-voltage safety controller. The signal communication between the high-voltage box control unit 3 and the solid-state precharge diagnostic module 2 can be achieved based on the controller area network bus, local interconnection network bus or dedicated discrete I / O signal lines.

[0023] Specific Implementation Method Two: Combination Figure 3 This embodiment further defines the high-voltage box pre-charge current limiting and safety protection system described in Specific Embodiment 1. In this embodiment, the solid-state pre-charge diagnostic module 2 includes: Power topology unit 2-1 is used to inject diagnostic signals and perform adaptive current-limiting pre-charge; Sensing and acquisition unit 2-2 is used to acquire voltage and current data sequences; Local control unit 2-3 is used to control the power topology unit and process the collected data, and to perform pre-start fault diagnosis, adaptive current limiting pre-charging and charging status monitoring. Fault feature library storage units 2-4 are used to store comparison benchmark data for fault diagnosis before startup.

[0024] In this embodiment, after receiving the start command, the high-voltage box control unit 3 first confirms that the main contactor 1 is in the open state and sends a start command to the solid-state precharge diagnostic module 2. The solid-state precharge diagnostic module 2 performs an internal self-test, including checking the status of its internal power switches, sensors, and controllers. After passing the self-test, it sends a ready status back to the high-voltage box control unit 3.

[0025] With the main contactor 1 open, the solid-state pre-charge diagnostic module 2 enters the high-frequency pulse complex impedance detection stage before startup. In this stage, the solid-state pre-charge diagnostic module 2 injects a preset, low-energy high-frequency detection signal into the high-voltage load 5 (i.e., the bus capacitor and its downstream circuit), and simultaneously collects the voltage and current response data corresponding to the high-frequency detection signal.

[0026] Based on the collected voltage and current response data, the solid-state precharge diagnostic module 2 calculates the complex impedance characteristics of the high-voltage load 5 and quantifies and estimates the actual capacitance value of the load from the complex impedance characteristics. and actual equivalent series resistance The electrical parameters. The solid-state precharge diagnostic module 2 compares its calculated complex impedance characteristics and electrical parameters with the locally stored fault feature library to perform fault feature identification. Fault feature identification includes: Determine if there is a short circuit fault in the high-voltage load 5 (e.g., the complex impedance characteristics show extremely low pure resistivity). Determine if the main contactor 1 has a welding (adhesion) fault (e.g., the complex impedance characteristics exhibit the electrical characteristics of high voltage source 4). Confirm that the high-voltage load 5 is in a healthy capacitive state.

[0027] If the identification result is a fault, the solid-state precharge diagnostic module 2 will stop the precharge process and report the specific fault type code to the high-voltage box control unit 3.

[0028] If the screening result is healthy, the solid-state pre-charge diagnostic module 2 will initiate adaptive calibration of the charging curve. During this stage, the solid-state pre-charge diagnostic module 2 uses the actual capacitance value and actual equivalent series resistance value, quantized during the high-frequency pulse complex impedance detection stage before startup, as control parameters to calculate and set the target charging current value for subsequent active constant current pre-charging. and expected charging voltage slope For example, a target current can be set based on the actual equivalent series resistance value to control the heat generated during the pre-charging process.

[0029] Solid-state precharge diagnostic module 2 performs active constant current precharge. The solid-state switch inside the solid-state precharge diagnostic module 2 operates in switch converter mode, charging the bus capacitor with the calibrated target charging current value.

[0030] During the active constant current pre-charge process, the solid-state pre-charge diagnostic module 2 initiates parallel monitoring of charging ripple impedance. The solid-state pre-charge diagnostic module 2 utilizes the high-frequency switching ripple (voltage ripple and current ripple) inherent in the operation of the solid-state switch to calculate the dynamic complex impedance of the load in real time during charging. If an abnormal change occurs in the dynamic complex impedance (e.g., the bus capacitor suddenly breaks down internally during charging), the solid-state pre-charge diagnostic module 2 will immediately stop charging and report a fault.

[0031] When the solid-state precharge diagnostic module 2 detects that the voltage of the high-voltage load 5 has reached the preset threshold (e.g., 90% or 95%) of the voltage of the high-voltage source 4, it sends a precharge completion signal to the high-voltage box control unit 3.

[0032] After receiving the pre-charge completion signal, the high-voltage box control unit 3 sends a closing command to the main contactor 1 to make the main circuit open.

[0033] After confirming that the main contactor 1 is closed, the high-voltage box control unit 3 sends a stop command to the solid-state pre-charge diagnostic module 2. The solid-state pre-charge diagnostic module 2 then shuts down its power topology unit 2-1, completing this pre-charge protection process, and enters a low-power standby state.

[0034] See attached document Figure 3 The solid-state precharge diagnostic module 2 includes a power topology unit 2-1. The input of the power topology unit 2-1 is connected to the high-voltage source 4 (via the precharge branch), and the output is connected to the high-voltage load 5. The power topology unit 2-1 is the hardware actuator that performs precharge current control and diagnostic signal injection.

[0035] In one embodiment, the power topology unit 2-1 is implemented as a non-isolated DC-DC chopper circuit, such as a buck converter topology. Specifically, the power topology unit 2-1 includes: a main solid-state switch arranged in series, a cooperating freewheeling element, and an energy storage inductor arranged in series.

[0036] The main solid-state switch is a high-voltage power semiconductor device, such as a silicon carbide MOSFET or a gallium nitride HEMT, to withstand high-voltage operating environments and support high-frequency switching operation. The freewheeling element can be a diode or a synchronous rectifier solid-state switch. An energy storage inductor is used to smooth the current, enabling continuous current control.

[0037] Power topology unit 2-1 is connected to local control unit 2-3 and receives drive signals from local control unit 2-3. Power topology unit 2-1 is configured to operate in at least two different operating modes: Active constant current pre-charge mode: In this mode, the local control unit 2-3 provides a high-frequency pulse width modulation (PWM) control signal to the power topology unit 2-1 (specifically, the gate driver of the main solid-state switch). The power topology unit 2-1 operates as a switching converter, adjusting the duty cycle of the PWM control signal and combining it with the real-time current value fed back by the sensing and acquisition unit 2-2 to achieve closed-loop control of the charging current, stabilizing it at the calibrated target charging current value. superior.

[0038] High-frequency pulse impedance detection mode: In this mode, the local control unit 2-3 provides a preset pulse train or a modulation signal of a specific frequency to the same power topology unit 2-1. The energy of the modulation signal is controlled within a range insufficient to cause a significant DC voltage rise in the bus capacitor. The power topology unit 2-1 then operates in signal injection mode, converting the received control signal into a voltage or current detection waveform applied to the high-voltage load 5.

[0039] In another embodiment, power topology unit 2-1 employs other solid-state circuit topologies capable of achieving current control and signal injection. For example, a simple chopper circuit consisting of a single solid-state switch and a current-limiting inductor, or a solid-state switch configured to operate in a controlled linear operating region (rather than a switching state), is used to achieve current control.

[0040] Reference Appendix Figure 3 The solid-state precharge diagnostic module 2 also includes a sensing and acquisition unit 2-2. The sensing and acquisition unit 2-2 is used to monitor in real time the voltage at the output terminal of the power topology unit 2-1 (i.e., the voltage of the high-voltage load 5) and the current flowing through the power topology unit 2-1. The output data of the sensing and acquisition unit 2-2 is provided to the local control unit 2-3.

[0041] In one embodiment, the sensing and acquisition unit 2-2 includes a current sensing subunit and a voltage sensing subunit.

[0042] The current sensing subunit measures the instantaneous current flowing to the high-voltage load 5. To support subsequent high-frequency pulse impedance detection and ripple impedance monitoring during charging, the current sensing subunit has a high measurement bandwidth. The measurement bandwidth is configured to respond sufficiently to the frequency of the probe signal injected during the high-frequency pulse impedance detection phase, as well as the switching frequency current ripple generated when the power topology unit 2-1 operates in active constant current pre-charge mode.

[0043] In one specific embodiment, the current sensing subunit is a Hall effect-based current sensor or a magnetoresistive effect-based current sensor. Such sensors can provide electrical isolation between the high-voltage source 4 and the low-voltage circuitry of the local control unit 2-3.

[0044] A voltage sensing subunit is used to measure the instantaneous voltage value of the high-voltage load 5 (i.e., across the bus capacitor). The voltage sensing subunit has a high common-mode rejection ratio to accurately measure the differential voltage signal floating on the high-voltage common-mode level. In one embodiment, the voltage sensing subunit is a high-complex-impedance precision resistor divider network, whose divided signal output is coupled to an isolation amplifier. In another embodiment, the voltage sensing subunit is an integrated isolated differential voltage sensor.

[0045] The sensing and acquisition unit 2-2 also includes a signal conditioning circuit and an analog-to-digital converter. The analog signals output from the current sensing subunit and the voltage sensing subunit are transmitted to the signal conditioning circuit (e.g., for anti-aliasing filtering). The conditioned analog signals are then input to one or more analog-to-digital converters.

[0046] To accurately capture the response waveform and switching ripple dynamics of the high-frequency probe signal, the analog-to-digital converter (ADC) features a high sampling rate and high resolution. The sampling rate of the ADC is set to be much higher than the switching frequency of the power topology unit 2-1 in active constant current precharge mode and the highest probe frequency used in the high-frequency pulse complex impedance detection stage, in order to meet the requirements of the Nyquist theorem and ensure accurate digital acquisition of voltage and current waveforms (including their DC and high-frequency AC components).

[0047] The analog-to-digital converter will collect the instantaneous voltage. Data sequences and instantaneous current The data sequence is provided to the local control unit 2-3 in real time for subsequent complex impedance calculation, fault identification, adaptive calibration, and closed-loop control of the charging process.

[0048] Reference Appendix Figure 3 The solid-state pre-charge diagnostic module 2 also includes a local control unit 2-3. The local control unit 2-3 is connected to the power topology unit 2-1, the sensing and acquisition unit 2-2, and the fault feature database storage unit 2-4. The local control unit 2-3 also includes a communication interface for signal communication with the high-voltage box control unit 3.

[0049] In one embodiment, the local control unit 2-3 is a microcontroller, digital signal processor, or field-programmable gate array, which integrates a processor core, program memory, data memory, and related peripheral interfaces, such as a pulse width modulation signal generator, an analog-to-digital converter control interface, and a serial communication interface.

[0050] Local control unit 2-3 is configured to execute the core control logic and algorithm calculations of solid-state pre-charge diagnostic module 2. The specific functional configuration of local control unit 2-3 is as follows: The power topology unit 2-1 generates and outputs a detection drive signal to the drive circuit of the power topology unit 2-1. During the high-frequency pulse complex impedance detection stage before startup, the power topology unit 2-1 can be controlled to inject a preset detection waveform into the high-voltage load 5.

[0051] Configure and control the analog-to-digital converter of sensing and acquisition unit 2-2 to start sampling, and receive the digitized instantaneous voltage data sequence and instantaneous current data sequence from sensing and acquisition unit 2-2.

[0052] The complex impedance calculation algorithm is executed, which is configured to perform calculations based on the received instantaneous voltage and current data sequences, using time-domain analysis or frequency-domain transformation (e.g., Fast Fourier Transform), to calculate the complex impedance characteristics of the high-voltage load 5, and to quantify and estimate the actual capacitance value from the complex impedance characteristics. and actual equivalent series resistance .

[0053] The fault identification logic is executed. The fault identification logic is configured to retrieve the pre-stored fault feature model from the fault feature library storage unit 2-4, and compare the fault feature model with the calculated complex impedance characteristics and quantization parameters to determine whether the high-voltage load 5 has a short circuit fault, whether the main contactor 1 has a welding fault, or whether the load is in a healthy state.

[0054] The adaptive calibration algorithm for the charging curve is executed. This algorithm is configured to: when the identification result indicates a healthy state, based on the quantized result... and Calculate and set the target charging current value required for the active constant current pre-charge mode. and expected charging voltage slope .

[0055] A pulse width modulation control signal is generated and output to the drive circuit of power topology unit 2-1 to enable power topology unit 2-1 to operate in switching converter mode in active constant current precharge mode.

[0056] Execute a closed-loop constant current control algorithm, such as a proportional-integral (PI) control algorithm, which is configured to: use a calibrated constant current control algorithm. Using the real-time charging current fed back by the sensing and acquisition unit 2-2 as the feedback value, the duty cycle of the pulse width modulation control signal is dynamically adjusted through calculation to achieve closed-loop control of the charging current.

[0057] The charging ripple impedance monitoring algorithm is executed, and the charging ripple impedance monitoring algorithm is configured to: extract the high-frequency ripple component (i.e., ...) from the feedback data of the sensing and acquisition unit 2-2 through digital filtering. and It also calculates the dynamic complex impedance during the charging process in real time. It is used for parallel instantaneous abnormal state monitoring.

[0058] The management communication interface is used to report the module self-test status, fault identification results (including specific fault type codes), pre-charge process status, and final pre-charge completion signal to the high-voltage box control unit 3.

[0059] See attached document Figure 3 The solid-state pre-charge diagnostic module 2 also includes a fault feature library storage unit 2-4. The fault feature library storage unit 2-4 is connected to the local control unit 2-3 and is used to store one or more comparison benchmark data required by the local control unit 2-3 when performing the fault feature identification stage.

[0060] In one embodiment, the fault feature library storage units 2-4 are non-volatile memories, such as flash memory or electrically erasable programmable read-only memory. The use of non-volatile memory ensures that the comparison reference data stored therein is not lost after the solid-state precharge diagnostic module 2 is powered off.

[0061] The comparison benchmark data stored in fault feature library storage units 2-4 can be specifically divided into multiple models or parameter sets, for example: Health State Model: Electrical characteristics of the high-voltage load 5 when it is in a healthy state. The health state model may include: one or more reference complex impedance characteristics characterizing the healthy bus capacitance (e.g., the range of complex impedance amplitude and the range of complex impedance phase angle at a specific probe frequency or band); upper and lower thresholds for acceptable actual capacitance values; and upper thresholds for acceptable equivalent series resistance.

[0062] Load short-circuit model: Electrical characteristics of a high-voltage load 5 when a short-circuit fault occurs. The load short-circuit model can be defined as a purely resistive complex impedance characteristic that exhibits extremely low resistance (e.g., resistance below a preset short-circuit threshold) within the detection frequency band.

[0063] Main Contactor 1 Welding Model: Electrical characteristics of main contactor 1 when a welding (adhesion) fault occurs. The main contactor 1 welding model is defined as the complex impedance characteristics of the high-voltage source 4 itself. The complex impedance characteristics are characterized, for example, by the low DC internal resistance and parasitic inductance of the high-voltage source 4. Its complex impedance characteristics at the detection frequency during the high-frequency pulse complex impedance detection stage are distinguishable from both the healthy state model and the load short-circuit model.

[0064] When performing fault identification, the local control unit 2-3 retrieves one or more model data from the fault feature library storage unit 2-4 and compares them with the complex impedance characteristics and quantization parameters calculated in real time during the high-frequency pulse complex impedance detection stage to complete the judgment of the system state.

[0065] See attached document Figure 2 and attached Figure 3 During the high-frequency pulse impedance detection phase before startup, the local control unit 2-3, after confirming that the main contactor 1 is in the open state, controls the power topology unit 2-1 to inject a preset detection signal into the high-voltage load 5. The detection signal is a low-energy, high-frequency waveform, and the injected energy is controlled within a range that is insufficient to cause a significant increase in the DC voltage of the bus capacitor, thereby distinguishing the detection phase from the subsequent charging phase.

[0066] In one embodiment, the detection signal may be one or more square wave pulse trains at a specific frequency. In another embodiment, the detection signal is at a preset detection frequency. A sinusoidal signal is scanned within a range (e.g., 1 kHz to 100 kHz). The power topology unit 2-1 is driven by the local control unit 2-3 and operates in signal injection mode, applying the probe signal to the high-voltage load 5.

[0067] During the same period that the power topology unit 2-1 injects the detection signal, the sensing and acquisition unit 2-2 simultaneously acquires the instantaneous voltage of the high-voltage load 5 through its internal high-bandwidth sensor and high-sampling-rate analog-to-digital converter. Data sequence and instantaneous current flowing through the load Data sequence. The sensing and acquisition unit 2-2 transmits the acquired digital voltage data sequence and digital current data sequence to the local control unit 2-3 in real time.

[0068] After receiving the digital data sequence of voltage and current, the local control unit 2-3 performs complex impedance calculation and parameter quantization algorithms. In one embodiment, the local control unit 2-3 processes the acquired data... and The data sequence undergoes digital signal processing, such as Fast Fourier Transform, to extract the signal at the probe frequency from the time-domain signal. Complex voltage components and complex current components .

[0069] Subsequently, the local control unit 2-3 calculates the detection frequency based on the complex form of Ohm's law. Complex impedance under : ; in, In order to detect frequency The complex impedance below; In order to detect frequency Below, through signal processing, from instantaneous voltage Complex voltage components extracted from a data sequence; In order to detect frequency Below, through signal processing, from instantaneous current Complex current components extracted from a data sequence.

[0070] Local control unit 2-3 further from complex impedance (Including complex impedance amplitude and complex impedance phase angle), the actual capacitance value of the high-voltage load 5 is quantitatively estimated by fitting or calculating parameters through a preset circuit model (such as a series RC circuit model) during the process. and actual equivalent series resistance .

[0071] In another embodiment, if the detection signal is a square wave pulse, the local control unit 2-3 can also analyze it. and The time-domain response characteristics (e.g., voltage slope and current peak) are used to fit and estimate. and .

[0072] See attached document Figure 2 and attached Figure 3 During the fault characteristic identification phase, the local control unit 2-3 uses the complex impedance characteristics calculated during the detection phase. Actual capacitance value and actual equivalent series resistance The data is compared with the comparison benchmark data pre-stored in the fault feature library storage units 2-4.

[0073] If the local control unit 2-3 makes the following judgment: The complex impedance characteristics conform to the healthy capacitance model pre-stored in the fault feature library storage unit 2-4. It is located between the preset lower and upper threshold values ​​of the health capacitance value; If the voltage is below the preset upper limit threshold of the equivalent series resistance for health, the local control unit 2-3 determines that the high-voltage load 5 is in a healthy state and allows the system to enter the subsequent adaptive charging calibration phase.

[0074] If the local control unit 2-3 makes the following judgment: Within the detection frequency band, the load exhibits an extremely low complex impedance value, with a phase angle close to zero (i.e., exhibiting purely resistive characteristics). This complex impedance value is lower than the load short-circuit complex impedance threshold pre-stored in the fault characteristic library storage unit 2-4. Therefore, the local control unit 2-3 determines that the high-voltage load 5 has a short-circuit fault. At this time, the local control unit 2-3 will abort the pre-charging process, keep the power topology unit 2-1 in the off state, and report a fault code indicating a load short circuit to the high-voltage box control unit 3.

[0075] If the local control unit 2-3 makes the following judgment: The complex impedance characteristics do not match the healthy capacitance model or the load short-circuit model, but instead match the complex impedance model of high-voltage source 4 in the pre-existing fault feature library storage unit 2-4 (for example, exhibiting the low DC internal resistance and parasitic inductance characteristics of high-voltage source 4). Therefore, the local control unit 2-3 determines that the main contactor 1 has a welding fault. At this time, the local control unit 2-3 also stops the pre-charging process and reports a fault code indicating welding of the main contactor 1 to the high-voltage box control unit 3.

[0076] After confirming that the system is in a healthy state, the local control unit 2-3 of the solid-state precharge diagnostic module 2 enters the charging curve adaptive calibration stage. In this stage, the actual equivalent series resistance estimated in the previous stage is used. and actual capacitance value The control parameters in the next stage of the active constant current mode are dynamically calibrated.

[0077] The purpose of this dynamic calibration is to ensure that the power loss (i.e., Joule heating) caused by the charging current flowing through the equivalent series resistance of the bus capacitor during the subsequent active constant current pre-charge process is controlled within a preset safety limit. This is to prevent overheating damage to the bus capacitor (especially capacitors whose equivalent series resistance has increased due to aging or defects) during the pre-charge process.

[0078] See attached document Figure 3 The local control unit 2-3 first retrieves a pre-set maximum capacitor heating power threshold from its internal fault feature database storage unit 2-4 (or a dedicated configuration storage area). Local control units 2-3 are based on the estimated Set the target charging current value. One specific setting method is to... Set as the system default charging current And the smaller of the upper limit of current calculated based on thermal power limitations: ; in, It is the target charging current value used for the next pre-charge stage after adaptive calibration; This represents a function that takes the minimum value and returns the parameter. and parameters The smaller of the; It is the system default charging current value preset in the local control unit 2-3, which serves as the reference charging current when there are no special restrictions; It is a preset threshold for the maximum instantaneous thermal power allowed to be generated across the equivalent series resistance during precharge, measured in watts (W). The local control unit 2-3 uses the measured complex impedance The actual equivalent series resistance estimated by the real part of the value reflects the current actual ohmic loss characteristics. The upper limit of current is calculated based on thermal power limitations.

[0079] The local control unit 2-3 will calculate this. The value is used as the target setting value for the closed-loop control algorithm in the subsequent active constant current pre-charge stage.

[0080] Determine the target charging current value Subsequently, the local control unit 2-3 further calculates the expected charging voltage slope. The expected charging voltage slope is based on the fundamental physical relationships of the capacitor and utilizes calibrated... and the estimated The calculations show that this serves as a monitoring benchmark for the subsequent charging process: ; in, This represents the DC voltage across the busbar. Indicates time The differential operator, therefore Represents bus voltage Rate of change over time; Theoretically, it is based on a target constant current. For capacitors During charging, the bus voltage Over time The expected slope of the changing charging voltage; It is the target charging current value used for the next pre-charge stage after adaptive calibration; The local control unit 2-3 uses the measured complex impedance The actual load-side capacitance value estimated by the imaginary part reflects the actual energy storage capacity of the current bus capacitor.

[0081] Local control unit 2-3 will calibrate the target charging current value and expected charging voltage slope The data is stored as a control input and judgment benchmark for the next stage of active constant current pre-charging and continuous monitoring.

[0082] See attached document Figure 2 and attached Figure 3 After completing the adaptive charging calibration, the local control unit 2-3 of the solid-state pre-charge diagnostic module 2 will enter the active constant current pre-charge stage.

[0083] During the active constant current pre-charge phase, the local control unit 2-3 will call upon the data generated during the adaptive calibration phase, based on... and Calculate and set the target charging current value and will The value is used as the setpoint for the closed-loop constant current control algorithm.

[0084] The local control unit 2-3 configures the power topology unit 2-1 to operate in switching converter mode (e.g., as a buck converter). The processor inside the local control unit 2-3 executes a closed-loop constant current control algorithm, such as a proportional-integral (PI) control algorithm.

[0085] During the active constant current pre-charge phase, the sensing and acquisition unit 2-2 continuously and in real time measures the actual charging current flowing through the power topology unit 2-1 and to the high-voltage load 5 through its current sensing subunit. The sensing and acquisition unit 2-2 provides the measured value of the actual charging current (via analog-to-digital converter) as a feedback value to the local control unit 2-3.

[0086] The closed-loop constant current control algorithm in local control unit 2-3 compares the feedback value (actual charging current) with the set value ( It performs real-time comparisons and dynamically and continuously adjusts the duty cycle of its output pulse width modulation control signal based on the deviation between the two.

[0087] A pulse width modulation (PWM) control signal is sent to the drive circuit of power topology unit 2-1 to control the on / off state of its internal main solid-state switch. Through this closed-loop regulation, local control unit 2-3 drives power topology unit 2-1, ensuring that the actual charging current flowing to the bus capacitor is precisely maintained at a certain level. The system achieves constant current charging of the bus capacitor. The constant current charging process continues until the voltage across the bus capacitor reaches a preset completion threshold.

[0088] During the same period when the solid-state precharge diagnostic module 2 performs the active constant current precharge phase, its local control unit 2-3 is configured to start and perform the charging ripple impedance monitoring phase in parallel.

[0089] Since the active constant current pre-charge stage is achieved through power topology unit 2-1 and a preset switching frequency... This is achieved through high-frequency switching operations (such as pulse width modulation chopping). Therefore, a current equal to the switching frequency will inevitably be superimposed on the DC charging current flowing to the high-voltage load 5. Related periodic current ripple components.

[0090] The current ripple component flowing through the high-voltage load 5 (i.e., the bus capacitor and its downstream circuit) will generate a corresponding voltage ripple component of the same frequency across the load terminals.

[0091] The sensing and acquisition unit 2-2 (equipped with high measurement bandwidth and high sampling rate) continuously acquires the instantaneous voltage of the high-voltage load 5 during the active constant current precharge execution. Data sequences and instantaneous current Data sequences. These acquired data sequences contain both a DC component for constant current control and a high-frequency ripple component for monitoring ripple complex impedance during charging.

[0092] Local control unit 2-3 receives instantaneous voltage Data sequences and instantaneous current After the data sequence is processed, the charging ripple complex impedance monitoring algorithm is executed. The charging ripple complex impedance monitoring algorithm first performs a digital filtering process (e.g., the center frequency is configured to be equal to...). A digital bandpass filter (DBS) is used to extract high-frequency ripple components from a data sequence.

[0093] Local control units 2-3 thus obtain the switching frequency Voltage ripple on and current ripple The amplitude and phase information.

[0094] Subsequently, the local control unit 2-3 calculates the dynamic complex impedance during the charging process in real time based on the extracted ripple component. In one embodiment, the calculation is performed in the following manner: ; in, The calculated dynamic complex impedance during charging; The complex representation of the extracted voltage ripple component (including amplitude and phase). The complex representation of the extracted current ripple component (including amplitude and phase).

[0095] Local control unit 2-3 will calculate in real time The voltage is continuously compared with the preset reference impedance to monitor whether the state of the high-voltage load 5 changes abruptly during the charging process.

[0096] In one embodiment, the reference complex impedance is not the complex impedance measured and stored during the high-frequency pulse complex impedance detection phase before startup. It is not a quantized value obtained during the detection phase, but an actual capacitance value. and actual equivalent series resistance And combined with the switching frequency of power topology unit 2-1 during the active constant current pre-charge stage The recalculated value at the switching frequency The theoretical health complex impedance value is as follows.

[0097] If local control unit 2-3 detects during the comparison If a significant and sudden characteristic deviation occurs (e.g., a sudden and catastrophic decrease in the amplitude of the complex impedance, or a sudden change in the capacitive characteristic of the complex impedance phase angle to a purely resistive characteristic), the local control unit 2-3 will determine that the high-voltage load 5 (e.g., the bus capacitor) has experienced an internal breakdown or short-circuit fault during charging.

[0098] When such a charging fault is detected, the local control unit 2-3 will immediately execute an instantaneous protection action, which includes: immediately shutting down the power topology unit 2-1 (i.e. stopping active constant current pre-charging) to cut off the fault current path, and reporting a specific fault code indicating a load short circuit during charging to the high-voltage box control unit 3.

[0099] Reference Appendix Figure 3 During the ripple impedance monitoring phase of charging, the local control unit 2-3 performs real-time complex impedance calculation and protection logic based on the high-frequency sampling data provided by the sensing and acquisition unit 2-2.

[0100] Local control unit 2-3 uses its internal digital signal processing algorithms (such as digital bandpass filters or fast Fourier transform algorithms) to analyze the instantaneous voltage sampled at high frequencies. Data sequences and instantaneous current From the data sequence, the switching frequency of power topology unit 2-1 is extracted. Voltage ripple component and current ripple component .

[0101] The local control unit 2-3 obtains the dynamic complex impedance during the charging process in real time by calculating the ratio of voltage ripple component to current ripple component. .

[0102] In obtaining real-time calculation Then, the local control unit 2-3 immediately executes the protection discrimination logic. The local control unit 2-3 retrieves the reference complex impedance. In one embodiment, The complex impedance value is not measured during the high-frequency pulse complex impedance detection phase before startup, but rather is the actual capacitance value quantized based on the high-frequency pulse complex impedance detection phase before startup. and actual equivalent series resistance And for the current switching frequency of power topology unit 2-1 The theoretical reference complex impedance is derived from the calculation.

[0103] Local control unit 2-3 real-time calculation and Percentage of deviation between In one embodiment, the percentage deviation is calculated as follows: ; in, The local control unit 2-3 will also calculate the percentage deviation between the dynamic complex impedance and the reference complex impedance; phase angle The load's electrical characteristics are monitored by comparing it to a preset capacitive phase angle range (e.g., -90° to -45°).

[0104] The local control unit 2-3 internally stores a charging fault detection threshold. , is a preset percentage value (e.g., 50%).

[0105] Local control unit 2-3 performs instantaneous protection judgment: if detected It suddenly exceeded within a very short time window (e.g., several switching cycles). ,or It suddenly deviates from the preset capacitive phase angle range (for example, it becomes a purely resistive characteristic close to 0°).

[0106] If any of the above conditions are met, the local control unit 2-3 will immediately determine that the high-voltage load 5 has experienced a sudden serious fault during the charging process, such as internal dielectric breakdown or plate short circuit.

[0107] In this situation, the local control unit 2-3 will trigger a transient protection action, immediately ceasing the transmission of pulse width modulation control signals to the power topology unit 2-1, thus turning off its main solid-state switch. The transient protection action is used to cut off the charging current instantaneously (e.g., on the microsecond scale) when a fault occurs, and its response speed is much faster than traditional overcurrent protection that relies on the accumulation of DC components.

[0108] At the same time, the local control unit 2-3 reports a specific fault code indicating a load short circuit during charging to the high-voltage box control unit 3 via the communication interface.

[0109] During the same period when the solid-state precharge diagnostic module 2 is performing the active constant current precharge phase, the local control unit 2-3 is configured to perform charging voltage slope anomaly monitoring in parallel, in addition to performing ripple impedance monitoring during charging.

[0110] The local control unit 2-3 uses the real-time bus voltage fed back by the sensing and acquisition unit 2-2 (i.e., instantaneous voltage) The rate of change of the actual charging voltage can be obtained by performing real-time differentiation on the DC component of the data sequence, or by calculating its voltage increment within a unit time window. .

[0111] Local control unit 2-3 will provide real-time updates. The expected charging voltage slope calculated and stored during the adaptive calibration phase. Continuous comparisons are conducted.

[0112] If the local control unit 2-3 detects that the rate of change of the actual charging voltage deviates significantly from (e.g., remains consistently lower than) the stored expected charging voltage slope, the local control unit 2-3 determines that the high-voltage load 5 has malfunctioned. This malfunction may indicate, for example, the existence of a previously undiagnosed parallel leakage path in the high-voltage load 5, or an unexpected change in the load capacitance characteristics. In this case, the local control unit 2-3 can be configured to perform protective actions (e.g., stop pre-charging) and report the corresponding abnormal status information to the high-voltage box control unit 3.

[0113] See attached document Figure 2 and attached Figure 3 During the active constant current pre-charge phase, the solid-state pre-charge diagnostic module 2 performs the judgment and switching phases in parallel.

[0114] During the judgment and switching phase, the sensing and acquisition unit 2-2 continuously and in real time monitors the bus voltage of the high-voltage load 5 through its voltage sensing subunit, and transmits this real-time voltage value. Provided to local control unit 2-3.

[0115] In one embodiment, the real-time bus voltage The local control unit 2-3 controls the instantaneous voltage provided by the sensing and acquisition unit 2-2. The DC component of the bus voltage is obtained by performing digital low-pass filtering or averaging on the data sequence.

[0116] The pre-charge completion voltage threshold is pre-stored in the internal memory of the local control unit 2-3 (e.g., fault feature library storage unit 2-4 or dedicated configuration storage area). Precharge completion voltage threshold It is a percentage (e.g., 90% or 95% of the nominal voltage) set according to the nominal voltage of the high voltage source 4, representing the target completion voltage of the pre-charge process.

[0117] During its control cycle of the active constant current pre-charge phase, the local control unit 2-3 continuously transmits the real-time bus voltage fed back by the sensing and acquisition unit 2-2. With pre-stored Thresholds are compared.

[0118] When local control unit 2-3 detects Greater than or equal to At that time, the local control unit 2-3 determines that the active constant current pre-charging stage has been completed.

[0119] Upon completion of the pre-charging determination, the local control unit 2-3 immediately executes a switching action. This switching action includes: the local control unit 2-3 immediately ceasing to send pulse width modulation control signals to the drive circuit of the power topology unit 2-1. This action causes the main solid-state switch of the power topology unit 2-1 to enter the off state, thereby stopping the active constant current pre-charging process.

[0120] Local control unit 2-3 sends a clear pre-charge completion status signal to high-voltage box control unit 3 through its communication interface.

[0121] After receiving the pre-charge completion status signal, the high-voltage box control unit 3 will execute the subsequent main contactor 1 closing operation, that is, command the main contactor 1 to close, so as to connect the high-voltage source 4 and the high-voltage load 5 through the main circuit path. After sending the pre-charge completion signal, the solid-state pre-charge diagnostic module 2 enters the standby state.

[0122] Specific Implementation Method Three: This implementation method further defines the high-voltage box pre-charge current limiting and safety protection system described in Specific Implementation Method Two. In this implementation method, the local control unit 2-3 is configured to perform the pre-start fault diagnosis, specifically including: The power topology unit 2-1 is controlled to inject a high-frequency detection signal into the high-voltage load 5; Based on the instantaneous voltage data sequence and the instantaneous current data sequence acquired by the sensing and acquisition unit 2-2, the complex voltage component and the complex current component at the frequency of the high-frequency detection signal are extracted by frequency domain transformation, and the ratio of the complex voltage component to the complex current component is calculated to obtain the complex impedance characteristics of the high-voltage load 5, and the actual capacitance value and the actual equivalent series resistance are quantitatively estimated. The complex impedance characteristics, the actual capacitance value, and the actual equivalent series resistance are compared with the comparison benchmark data pre-stored in the fault feature library storage unit to determine whether the high-voltage load 5 has a short-circuit fault and whether the main contactor 1 has a welding fault.

[0123] In this embodiment, the health status of the load can be determined without disassembling the system, and the capacitance value and ESR can be quantified to provide a precise parameter basis for subsequent adaptive charging; short circuits / welding can be identified in advance to avoid "starting with defects" and improve system reliability and safety.

[0124] Specific Implementation Method Four: This implementation method further defines the high-voltage box pre-charging current limiting and safety protection system described in Specific Implementation Method Three. In this implementation method, the local control unit 2-3 is further configured to perform the adaptive current limiting pre-charging, specifically including: When the pre-start fault diagnosis results are in a healthy state, the preset maximum capacitor heating power threshold is retrieved. Based on the maximum heating power threshold of the capacitor and the quantified actual equivalent series resistance, the upper limit of the current is calculated, and then the target charging current value required for the adaptive current limiting pre-charging is set.

[0125] In this embodiment, the charging current is dynamically set, taking into account both the capacitor's heat resistance and charging efficiency, avoiding the "overheating or too slow" problems of traditional fixed resistor current limiting; extending the capacitor's lifespan, it is especially suitable for safe pre-charging of aging capacitors or in high-temperature environments.

[0126] Specific Implementation Method Five: This implementation method further defines the high-voltage box pre-charging current limiting and safety protection system described in Specific Implementation Method Four. In this implementation method, the local control unit 2-3 is configured to perform the adaptive current limiting pre-charging, including: The power topology unit 2-1 is configured to operate in switching converter mode, and the target charging current value is used as the set value. The actual charging current fed back by the sensing and acquisition unit 2-2 is used as the feedback value. A closed-loop constant current control algorithm is executed to complete the adaptive current limiting pre-charging.

[0127] In this embodiment, the above settings achieve high-precision constant current control, ensuring stable charging current unaffected by input voltage fluctuations; solid-state switches replace traditional resistors, eliminating heat loss, resulting in high efficiency, small size, and long lifespan; and they support a wide range of load adaptation, suitable for different capacitor capacities and voltage levels.

[0128] Specific Implementation Method Six: This implementation method further defines the high-voltage box pre-charging current limiting and safety protection system described in Specific Implementation Method Five. In this implementation method, the local control unit 2-3 is configured to perform the charging status monitoring and obtain the dynamic complex impedance in real time during the charging process, specifically including: During the same period of performing the adaptive current-limiting pre-charging, the voltage ripple component and the current ripple component are extracted from the instantaneous voltage data sequence and the instantaneous current data sequence collected by the sensing and acquisition unit 2-2 using the inherent switching frequency of the power topology unit 2-1 when operating in the switching converter mode; and the dynamic complex impedance during the charging process is obtained in real time by calculating the ratio of the voltage ripple component to the current ripple component.

[0129] In this embodiment, no additional sensors are required, existing voltage / current sampling channels are reused, resulting in low cost; it reflects changes in load status in real time, and responds to faults such as capacitor breakdown and short circuits in microseconds; it provides online monitoring without interrupting the charging process and offers disturbance-free protection.

[0130] Specific Implementation Method Seven: This implementation method further defines the high-voltage box pre-charge current limiting and safety protection system described in Specific Implementation Method Six. In this implementation method, the local control unit 2-3 is further configured as follows: The real-time dynamic complex impedance is continuously compared with the reference complex impedance; when a sudden characteristic deviation of the dynamic complex impedance is detected, it is determined that the high-voltage load 5 has an internal breakdown or short circuit fault during the charging process, and the adaptive current limiting pre-charging is immediately stopped to perform instantaneous protection action.

[0131] In this embodiment, the above-mentioned settings enable strong identification of sudden faults, detecting early failures such as internal breakdown and plate short circuits; rapid shutdown protection to prevent the accumulation of fault energy and avoid the main contactor closing on the failed load; and reporting fault codes to facilitate remote diagnosis and maintenance.

[0132] Specific Implementation Method Eight: This implementation method further defines the high-voltage box pre-charge current limiting and safety protection system described in Specific Implementation Method Seven. In this implementation method, the reference complex impedance is a theoretical reference complex impedance calculated based on the actual capacitance value and the actual equivalent series resistance obtained by quantification during the pre-start fault diagnosis stage, and for the current switching frequency of the power topology unit 2-1.

[0133] In this implementation, the reference value is personalized to match the actual state of the current load, avoiding misjudgment; the frequency is adaptive, applicable to different switching frequency topologies, improving compatibility; and the protection accuracy is improved, reducing false alarms / missed alarms.

[0134] Specific Implementation Method Nine: This implementation method further defines the high-voltage box pre-charge current limiting and safety protection system described in Specific Implementation Method Five. In this implementation method, the local control unit 2-3 is further configured as follows: Based on the target charging current value and the actual capacitance value, the expected charging voltage slope is obtained and stored by calculating the ratio of the target charging current value to the actual capacitance value. During the same period of performing the adaptive current limiting pre-charging, the actual charging voltage at the high-voltage load terminal is continuously monitored. The rate of change of the actual charging voltage is compared with the expected charging voltage slope. When the rate of change of the actual charging voltage deviates from the expected charging voltage slope, it is used to determine that the high-voltage load 5 has become abnormal.

[0135] In this embodiment, the above-mentioned settings identify hidden faults such as parallel leakage and capacitance characteristic drift; the dual verification mechanism is redundant with the complex impedance monitoring, improving diagnostic coverage; no additional hardware is required, and the software algorithm is used to enhance safety at zero cost.

[0136] Specific Implementation Method Ten: This implementation method further defines the high-voltage box pre-charge current limiting and safety protection system described in Specific Implementation Method Seven. In this implementation method, the local control unit 2-3 is further configured as follows: After determining that the high-voltage load 5 has malfunctioned during charging and stopping the adaptive current-limiting pre-charging, the system immediately reports diagnostic status information to the high-voltage box control unit 3. The diagnostic status information is used to indicate that the charging status monitoring has identified a fault.

[0137] In this implementation, faults are traceable, facilitating system-level fault recording and OTA analysis; fault classification is supported, such as "short circuit during charging" and "capacitor breakdown," guiding precise repairs; the system's intelligence level is improved, adapting to the needs of intelligent connected vehicles / energy storage cloud platforms.

[0138] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A high-voltage tank pre-charge current limiting and safety protection system, characterized in that, The main contactor (1), the solid-state pre-charge diagnostic module (2) and the high-voltage tank control unit (3) are included. The main contactor (1) is used for turning on or turning off the main circuit between the high-voltage source (4) and the high-voltage load (5). The solid-state pre-charge diagnostic module (2) is connected in parallel with the main contactor (1) and is used for performing pre-charge and fault diagnosis in the off state of the main contactor (1). The high-voltage tank control unit (3) is used for controlling the cooperation of the main contactor (1) and the solid-state pre-charge diagnostic module (2); wherein the high-voltage tank control unit (3) is configured to: Before the main contactor (1) is turned on, instruct the solid-state pre-charge diagnostic module (2) to perform pre-start fault diagnosis; if the diagnosis result is healthy, instruct the high-voltage source (4) to perform adaptive current limiting pre-charge and charging state monitoring; after receiving the pre-charge completion signal, control the main contactor (1) to be turned on, and complete the high-voltage tank pre-charge process.

2. The pre-charge current limiting and safety protection system for a high voltage tank according to claim 1, wherein, The solid-state pre-charge diagnostic module (2) includes: The power topology unit (2-1) is used for injecting a diagnostic signal and performing adaptive current limiting pre-charge. The sensing and collecting unit (2-2) is used for collecting voltage and current data sequences. The local control unit (2-3) is used for controlling the power topology unit and processing collected data, performing pre-start fault diagnosis, adaptive current limiting pre-charge and charging state monitoring. The fault feature library storage unit (2-4) is used for storing comparison reference data for pre-start fault diagnosis.

3. The pre-charge current limiting and safety protection system for a high voltage tank according to claim 2, wherein, The local control unit (2-3) is configured to perform the pre-start fault diagnosis, specifically including: Control the power topology unit (2-1) to inject a high-frequency detection signal into the high-voltage load (5); Based on the instantaneous voltage data sequence and the instantaneous current data sequence collected by the sensing and collecting unit (2-2), the complex voltage component and the complex current component at the frequency of the high-frequency detection signal are extracted through frequency domain transformation, and the ratio of the complex voltage component to the complex current component is calculated to obtain the complex impedance characteristic of the high-voltage load (5), and the actual capacitance value and the actual equivalent series resistance are quantitatively estimated; Compare the complex impedance characteristic, the actual capacitance value and the actual equivalent series resistance with the pre-stored comparison reference data in the fault feature library storage unit to determine whether the high-voltage load (5) has a short circuit fault and whether the main contactor (1) has a welding fault.

4. The pre-charge current limiting and safety protection system for a high voltage tank according to claim 3, wherein, The local control unit (2-3) is also configured to perform the adaptive current limiting pre-charge, specifically including: When the pre-start fault diagnosis result is healthy, the preset maximum heating power threshold of the capacitor is called; And based on the maximum heating power threshold of the capacitor and the quantitatively obtained actual equivalent series resistance, the upper limit of the current is calculated, and then the target charging current value required by the adaptive current limiting pre-charge is set.

5. A pre-charge current limiting and safety protection system for a high voltage tank as claimed in claim 4, wherein, The local control unit (2-3) is configured to perform the adaptive current limiting pre-charge, specifically including: The power topology unit (2-1) is configured to work in a switching converter mode, and a closed-loop constant current control algorithm is performed using the target charging current value as a set value and using an actual charging current fed back by the sensing and collecting unit (2-2) as a feedback value, so as to complete the adaptive current-limiting pre-charging.

6. A pre-charge current limiting and safety protection system for a high voltage tank as defined in claim 5, wherein, The local control unit (2-3) is configured to obtain a dynamic complex impedance in a charging process in real time for performing the charging state monitoring, and specifically includes the following steps: In the same period of performing the adaptive current-limiting pre-charging, voltage ripple components and current ripple components are extracted from the instantaneous voltage data sequence and the instantaneous current data sequence collected by the sensing and collecting unit (2-2) by using a switching frequency inherent in the power topology unit (2-1) when working in the switching converter mode; and a dynamic complex impedance in a charging process is obtained in real time by calculating a ratio of the voltage ripple components to the current ripple components.

7. A pre-charge current limiting and safety protection system for a high voltage tank as defined in claim 6, wherein, The local control unit (2-3) is further configured to: The real-time obtained dynamic complex impedance is continuously compared with a reference complex impedance; when a sudden characteristic deviation of the dynamic complex impedance is monitored, it is determined that internal breakdown or short-circuit failure of the high-voltage load (5) occurs in a charging process, and the adaptive current-limiting pre-charging is immediately stopped for performing a transient protection action.

8. The pre-charge current limiting and safety protection system for a high voltage tank according to claim 7, wherein, The reference complex impedance is a theoretical reference complex impedance calculated based on the actual capacitance value and the actual equivalent series resistance quantified in the pre-starting fault diagnosis stage and for the current switching frequency of the power topology unit (2-1).

9. The pre-charge current limiting and safety protection system for a high voltage tank according to claim 5, wherein, The local control unit (2-3) is further configured to: An expected charging voltage slope is obtained and stored by calculating a ratio of the target charging current value to the actual capacitance value based on the target charging current value and the actual capacitance value; in the same period of performing the adaptive current-limiting pre-charging, an actual charging voltage at the high-voltage load end is continuously monitored; and a change rate of the actual charging voltage is compared with the expected charging voltage slope, so as to determine that the high-voltage load (5) is abnormal when the change rate of the actual charging voltage deviates from the expected charging voltage slope.

10. The pre-charge current limiting and safety protection system for a high voltage tank of claim 7, wherein, The local control unit (2-3) is further configured to: After it is determined that the high-voltage load (5) fails in a charging process and the adaptive current-limiting pre-charging is stopped, diagnosis state information is immediately reported to the high-voltage box control unit (3), and the diagnosis state information is used to indicate that the charging state monitoring has identified the failure.

Images