A grid-connected control method of a dual high-voltage power supply system

Abstract

This invention discloses a grid-connected control method for a dual high-voltage power supply system. It constructs two physically isolated independent buses: the first bus is connected to a generator and a long-term working load, while the second bus is connected to a supercapacitor and a short-term working load. The two buses are selectively electrically connected only through a grid-connected contactor, and hardware blocks invalid discharge paths from the supercapacitor to the long-term working load. The controller uses only the generator's effective enabling condition and the voltage difference across the grid-connected contactor meeting a preset threshold as the sole grid-connection trigger condition to control the on / off state of the grid-connected contactor. This invention solves problems such as power supply and load characteristic mismatch and complex grid-connection logic, significantly simplifies the control logic, and improves the system's power supply reliability, energy utilization, and adaptability to multiple scenarios.

Description

Technical Field

[0001] This invention relates to the field of vehicle high-voltage power supply control technology, and in particular to a grid-connected control method for a dual high-voltage power supply system. Background Technology

[0002] In high-voltage DC power supply scenarios for special vehicles, the system has stringent requirements for power supply reliability, operating condition adaptability, emergency response speed, and energy utilization efficiency. To balance the continuous and stable power supply needs of long-term workloads with the instantaneous peak power supply needs of short-term workloads, the industry commonly adopts a dual-power grid-connected distribution system combining a generator and a supercapacitor. The generator, with its continuous and stable power generation capacity, adapts to the power supply needs of long-term workloads, while the supercapacitor, with its high power density and rapid charge / discharge response characteristics, adapts to the peak energy replenishment needs of short-term workloads. However, limited by its own energy storage capacity, it is crucial to strictly avoid ineffective discharge to long-term workloads. Existing dual-power grid-connected control strategies suffer from multiple fatal architectural and logical flaws, making them fundamentally incapable of meeting the stringent requirements of high-voltage power supply systems for special vehicles.

[0003] Existing dual-power grid-connected architectures generally adopt a single-bus centralized topology, where long-duration loads, short-duration loads, generators, and supercapacitors are all mixed together on the same high-voltage bus. This completely fails to achieve the characteristic binding design between loads and power sources, resulting in a fundamental architectural flaw. This flaw directly leads to the supercapacitor's limited energy storage being continuously and ineffectively consumed by long-duration loads when connected to power, rapidly depleting its energy reserves. At critical nodes such as the start-up of the operating system and the activation of emergency protection systems, it is completely unable to provide sufficient power support for short-duration impact loads, seriously threatening the operational safety of special vehicles.

[0004] Existing grid-connected control strategies suffer from severe logical redundancy and reliability defects. Due to the fundamental differences in output characteristics and energy response speed between generators and supercapacitors, and the highly random nature of power supply operating states, the grid connection sequence directly determines system operational safety. Existing solutions must strictly distinguish the power-on sequence of the two power supplies, identify multi-dimensional power supply operating states, and match complex and ever-changing vehicle operating conditions to complete grid-connected control, resulting in extremely cumbersome and complex control logic. This defect not only significantly consumes the core computing power of the on-board controller but also easily leads to fatal faults such as timing disorders, grid connection failures, and accidental closing in scenarios with drastic changes in special vehicle operating conditions. This can further cause serious safety accidents such as high-voltage system short circuits and high-current surges that burn out core components, making it unsuitable for the complex and ever-changing operating conditions of special vehicles.

[0005] In summary, existing dual-power grid-connected control strategies cannot fundamentally solve the core problems of power supply and load characteristics mismatch and complex grid-connection logic with poor reliability. They also have shortcomings such as insufficient emergency power supply capacity and lack of pre-charging safety management, making it difficult to meet the stringent usage requirements of high-voltage power supply systems for special vehicles. There is an urgent need for improvement and optimization. Summary of the Invention

[0006] The purpose of this invention is to provide a grid-connected control method for a dual high-voltage power supply system, which solves problems such as power supply and load characteristic mismatch and complex grid-connection logic, significantly simplifies the control logic, and improves the system's power supply reliability, energy utilization, and adaptability to multiple scenarios. The specific technical solution is as follows: A grid-connected control method for a dual high-voltage power supply system includes the following steps: The system is equipped with physically isolated first and second buses. The first bus is electrically connected to the generator and long-term working load, while the second bus is electrically connected to the supercapacitor and short-term working load. A grid-connected contactor is connected in series between the first and second buses. The first and second buses are selectively electrically connected only through the grid-connected contactor, thereby blocking the power supply path from the supercapacitor to the long-term working load on the first bus in a hardware manner. The controller uses only the generator enable signal and the bus voltage difference across the grid-connected contactor meeting a preset threshold as the sole grid-connected trigger conditions. When both conditions are met, the controller closes the grid-connected contactor to achieve dual-bus grid-connected operation. When the generator enable is invalid, the controller keeps the grid-connected contactor open, and the second bus is powered independently by the supercapacitor for short-term working loads.

[0007] Furthermore, an internal contactor is provided between the supercapacitor and the second busbar. When the controller detects that the voltage of the supercapacitor reaches the rated value and the voltage difference between the supercapacitor and the second busbar meets the preset access threshold, it controls the internal contactor to close, so that the supercapacitor is connected to the second busbar.

[0008] Furthermore, the supercapacitor has a built-in charger, which is electrically connected to the vehicle's low-voltage battery. After the low-voltage battery is powered on, the charger converts the electrical energy of the low-voltage battery into high-voltage electrical energy to replenish the supercapacitor until the supercapacitor voltage reaches the rated value. When the supercapacitor voltage is lower than the preset replenishment threshold, the charger automatically starts to replenish the supercapacitor.

[0009] Furthermore, when the first bus and the second bus are connected to the grid, the generator supplies power to both long-term and short-term working loads simultaneously through the first bus, the closed grid-connected contactor, and the second bus; when the grid-connected contactor is open, the supercapacitor can only supply power to the short-term working load on the second bus and cannot supply power to the long-term working load on the first bus.

[0010] Furthermore, a first pre-charge circuit is connected in parallel across both ends of the grid-connected contactor. The trigger condition for the first pre-charge circuit is that the generator is enabled. When the generator is enabled, the controller first starts the first pre-charge circuit to pre-charge the second bus and the short-term working load until the bus voltage difference across both ends of the grid-connected contactor meets the preset threshold, and then controls the grid-connected contactor to close.

[0011] Furthermore, the long-term working load includes a controlled long-term working load, and a second pre-charge circuit is connected in parallel across the two ends of the second power distribution contactor of the controlled long-term working load; the trigger condition of the second pre-charge circuit is that the load working command is valid and the generator is enabled. The controller starts the second pre-charge circuit to pre-charge the controlled long-term working load until the voltage difference across the second power distribution contactor meets the preset threshold, then closes the second pre-charge circuit and connects the second power distribution contactor.

[0012] Furthermore, the long-duration workload also includes an uncontrolled long-duration workload, which is directly electrically connected to the generator output terminal and pre-charged by the gently rising ramp voltage output by the generator.

[0013] Furthermore, a third pre-charge circuit is connected in parallel across the two ends of the third distribution contactor of the short-time working load; the triggering condition of the third pre-charge circuit is that the load working command is valid and the generator is enabled or the supercapacitor has been connected to the second bus; the controller starts the third pre-charge circuit to pre-charge the short-time working load until the voltage difference across the third distribution contactor meets the preset threshold, then closes the third pre-charge circuit and connects the third distribution contactor.

[0014] Furthermore, a current-limiting resistor is connected in series in the first pre-charge circuit, the second pre-charge circuit, and the third pre-charge circuit to suppress the inrush current during the pre-charge process.

[0015] Furthermore, each precharge circuit is equipped with an overtime protection mechanism. If the precharge duration exceeds the preset time and the precharge completion condition is not met, the controller will shut down the corresponding precharge circuit, stop power distribution, and report a precharge fault.

[0016] The grid-connected control method for the dual high-voltage power supply system of the present invention has the following advantages: 1. By constructing a dual-physical-isolated independent bus architecture, the generator and long-term workload, and the supercapacitor and short-term workload are rigidly bound by characteristics. A single grid-connected contactor serves as the electrical connection path between the two buses, completely blocking the ineffective discharge path of the supercapacitor to the long-term workload from the hardware level. This fundamentally solves the core pain points of the existing single-bus architecture, namely the mismatch between power supply and load characteristics and the ineffective consumption of supercapacitor energy by the long-term workload. At the same time, it abandons the complex grid connection logic that relies on power-on timing and multi-condition identification in existing technologies. It uses only the effective enabling of the generator and the standard voltage difference across the grid-connected contactor as the sole grid connection trigger conditions, which greatly simplifies the control logic, reduces the computing power requirements of the vehicle controller, and completely avoids the risk of timing disorder and incorrect grid connection when the operating conditions change suddenly. It also realizes the independent emergency power supply of the supercapacitor to the short-term workload when the generator is not working, which significantly improves the system's power supply reliability, energy utilization rate and multi-scenario adaptability.

[0017] 2. By setting a controllable internal contactor between the supercapacitor and the second busbar, and using the supercapacitor voltage reaching its rated value and the voltage difference between the supercapacitor and the second busbar meeting a preset access threshold as dual constraints for contactor closure, the unique control of the supercapacitor's access to the busbar is achieved. This completely avoids the problem of inrush current during closing caused by random voltage fluctuations and excessive voltage difference between the two sides during access. It effectively protects the supercapacitor cells, contactors, and other core high-voltage components, significantly improving the safety and stability of the supercapacitor access process. At the same time, it provides a stable and reliable power supply foundation for independent power supply of the supercapacitor and grid-connected operation of the dual busbars.

[0018] 3. By configuring a built-in charger that is electrically connected to the vehicle's low-voltage battery for the supercapacitor, and setting up a closed-loop control logic that automatically starts when low-voltage power is applied, automatically stops when rated voltage is applied, and automatically replenishes power when the voltage is below a threshold, the supercapacitor obtains a power replenishment path that is completely independent of the high-voltage generator. This completely solves the pain point of existing technologies where supercapacitor power replenishment is completely dependent on the generator, and the supercapacitor loses its power replenishment and emergency power supply capabilities when the generator stops or fails. Even if the high-voltage generator is in an abnormal state, the supercapacitor can autonomously replenish power through the low-voltage battery and maintain a fully charged standby state, which greatly improves the system's power supply redundancy and adaptability to extreme operating conditions, and meets the stringent requirements of vehicle high-voltage systems for multiple power supply backups.

[0019] 4. By clearly defining the power supply authority control rules under two operating conditions—dual busbar grid-connected operation and grid-connected contactor disconnection—a dual guarantee of hardware topology constraints and software logic control is formed. In grid-connected mode, the generator's continuous power supply capability is fully utilized, achieving full coverage power supply of long-term and short-term full loads by a single power source, maximizing the generator's power supply efficiency. When the grid-connected contactor is disconnected, it is logically clarified that the supercapacitor can only supply power to short-term working loads on the second busbar, completely blocking the path of ineffective discharge of the supercapacitor to long-term working loads. This achieves precise allocation and efficient utilization of vehicle energy, while ensuring clear and unambiguous power supply control logic boundaries, avoiding safety risks caused by erroneous power supply.

[0020] 5. By connecting the first pre-charge circuit in parallel across the grid-connected contactor and effectively binding the triggering condition of the pre-charge circuit with the generator enable, deep linkage between grid-connected pre-charge and the main power supply readiness state is achieved. This fundamentally eliminates the problem of "pre-charge circuit engaging prematurely" in existing technologies, which occurs before the power supply is powered on and voltage is built up. This avoids faults such as reverse discharge and high-current surges. At the same time, by charging the supporting capacitors of the second busbar and short-term working load in advance through the pre-charge circuit, it ensures that the voltage difference between the two sides reaches the standard when the grid-connected contactor is closed. This completely eliminates the surge current at the moment of grid connection, effectively protects core components such as the grid-connected contactor and high-voltage supporting capacitors, and significantly improves the safety and reliability of the dual-busbar grid connection process.

[0021] 6. A second pre-charge circuit is configured in parallel across the two ends of the distribution contactor for the controlled long-duration workload. The pre-charge trigger condition is set to a dual constraint of the load working command being valid and the generator being enabled. This achieves on-demand triggering of pre-charge for the controlled long-duration workload, initiating pre-charge only when the load has a clear power-on requirement, thus avoiding energy loss caused by invalid pre-charge. Furthermore, the pre-constraint of the generator being enabled ensures that the main power supply is ready when pre-charge starts, eliminating the risk of invalid pre-charge and reverse discharge when there is no effective power supply. At the same time, the pre-charge process eliminates the inrush current at the moment of load power-on, ensuring the safety of the controlled long-duration workload during power-on. This forms a complete logical closed loop with the rigid binding architecture of the generator-long-duration workload. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a dual high-voltage power supply system.

[0023] Figure 2 This is a flowchart of the grid connection control method for a dual high-voltage power supply system. Detailed Implementation

[0024] To better understand the purpose, structure, and function of this invention, the grid-connected control method of the dual high-voltage power supply system of this invention will be described in detail below with reference to embodiments and accompanying drawings.

[0025] The present invention provides a grid-connected control method for a dual high-voltage power supply system, which is applied to the on-board DC microgrid of a hybrid electric drive system for special vehicles. It can adapt to the differentiated power supply requirements of long-term and short-term working loads, while meeting the requirements of high-voltage power supply systems for safety, reliability and control simplicity.

[0026] like Figure 1 and Figure 2 As shown, the dual high-voltage power supply system based on this embodiment includes a generator as the first high-voltage power supply, a supercapacitor 1 as the second high-voltage power supply, at least one long-term working load, at least one short-term working load 11, a grid-connected contactor 2, and a controller for executing control logic. In this embodiment, the controller is a vehicle controller. The generator, the long-term working load, and the short-term working load 11 are all equipped with supporting capacitors for filtering and voltage stabilization at their front ends. The supercapacitor 1 has an internal contactor for controlling its connection and disconnection with the bus, and a charger 3 for autonomous power replenishment. The system is also equipped with multiple pre-charge circuits, which correspond to the pre-charge requirements of the grid connection process, the power-on of the long-term working load, and the power-on of the short-term working load.

[0027] In this embodiment, two physically isolated independent high-voltage buses are first constructed to form a dual-zone hardware topology. The first bus serves as a dedicated power supply circuit for the generator, electrically connected to the generator's output and all long-term operating loads; the second bus serves as a dedicated power supply circuit for the supercapacitor 1, electrically connected to the supercapacitor 1's output and all short-term operating loads 11; the two buses are selectively electrically connected only through a grid-connected contactor 2, with no other electrical pathways.

[0028] It should be noted that this topology achieves a rigid binding of power supply and load characteristics at the hardware level. Based on the generator's continuous and stable power generation capacity, it adapts to the continuous power demand of long-term workloads. Simultaneously, based on the high power density and rapid charging / discharging characteristics of supercapacitor 1, it adapts to the instantaneous peak power demand of short-term workloads 11, fundamentally solving the pain point of load-power mismatch in existing single-bus architectures. Furthermore, this topology, through the on / off control of a single grid-connected contactor 2, and through the dual independent bus architecture and grid-connected contactor 2, completely blocks the ineffective discharge path of supercapacitor 1 to long-term workloads at the hardware level in off-grid conditions. In grid-connected conditions, the generator acts as the main power source to continuously supply power to long-term workloads, logically preventing supercapacitor 1 from continuously discharging to long-term workloads. This avoids the limited energy storage of supercapacitor 1 being ineffectively consumed by long-term workloads, ensuring that it can provide sufficient power support for short-term impact loads when needed by the vehicle, fundamentally solving the problem of power supply failure at critical moments caused by the depletion of supercapacitor 1's energy storage.

[0029] Based on the above dual independent bus architecture, this embodiment has optimized the grid connection control logic to a very simple level. The vehicle controller uses only two parameters as the sole triggering conditions for grid connection: the effective enable signal of the generator and whether the bus voltage difference across the grid connection contactor 2 meets the preset threshold. The bus voltage difference is the voltage difference between the first bus and the second bus. Only when both conditions are met simultaneously will the controller output a control signal to close the grid connection contactor 2 and realize the grid connection operation of the dual buses. When the generator is not enabled, regardless of the state of the supercapacitor 1, the controller controls the grid connection contactor 2 to remain open. At this time, the second bus is only supplied with independent power by the supercapacitor 1 for the short-term working load 11.

[0030] It is important to emphasize that the grid connection logic in this embodiment abandons the complex judgment of power supply power-on sequence, multiple operating scenarios, and the working state of supercapacitor 1. It only uses generator enablement as the core pre-constraint for grid connection, establishing the generator as the core entity of grid-connected power supply. Grid connection is only allowed when the main power supply is ready, logically avoiding the risk of erroneous grid connection in the absence of a main power supply. At the same time, the bus voltage difference is used as a safety constraint for grid connection, ensuring that the potentials of the two buses are basically consistent at the moment of grid connection, avoiding the generation of large current surges. This setting simplifies the grid connection control logic, reduces the computing power requirements of the vehicle controller, and will not cause timing disorder even if the vehicle's operating conditions change drastically. This improves the reliability and response speed of grid connection control, and also enables supercapacitor 1 to provide independent emergency power supply for short-term workloads when the generator is not working, covering the power supply needs of more extreme operating conditions.

[0031] Preferably, to ensure the safety of supercapacitor 1 when connected to the second bus, this embodiment sets up an internal contactor between supercapacitor 1 and the second bus. The vehicle controller collects the current voltage of supercapacitor 1 and the real-time voltage of the second bus in real time. Only when the voltage of supercapacitor 1 reaches the rated operating value and the voltage difference between supercapacitor 1 and the second bus meets the preset connection threshold will a control signal be output to control the internal contactor to close, allowing supercapacitor 1 to connect to the second bus. When high-voltage devices are connected, if the voltage difference on both sides is too large, a momentary large current surge will be generated, which may shorten the service life of the device or even directly burn out core components such as the contactor and supercapacitor 1. This embodiment, through a dual-constraint connection logic, ensures that supercapacitor 1 is only allowed to connect to the bus when it is fully charged and the voltage difference with the bus meets the standard. This achieves unique control over the connection state of supercapacitor 1, completely avoiding the surge current at the moment of connection, and avoiding the connection safety hazards caused by random fluctuations in the voltage state of supercapacitor 1, thus ensuring the absolute safety of the connection process of supercapacitor 1.

[0032] In this embodiment, the supercapacitor 1 has a built-in bidirectional charger 3. The input end of the charger 3 is electrically connected to the vehicle's 28V low-voltage battery, and the output end is electrically connected to the cell assembly of the supercapacitor 1, forming an autonomous closed-loop energy replenishment system for the supercapacitor 1. After the vehicle is powered on at low voltage, the charger 3 automatically starts working, converting the low-voltage electrical energy of the vehicle's low-voltage battery into high-voltage electrical energy that matches the supercapacitor 1, replenishing the supercapacitor 1's energy until the supercapacitor 1's voltage reaches its rated operating value, at which point the charger 3 automatically stops working. During vehicle operation, when the charger 3 detects that the supercapacitor 1's voltage is lower than a preset energy replenishment threshold, it will automatically restart working to replenish the supercapacitor 1, ensuring that it is always in a fully charged standby state.

[0033] In this embodiment, the supercapacitor 1 is powered by a built-in charger 3, making its recharge path completely independent of the high-voltage generator. Based on the low-voltage battery that keeps the vehicle powered at all times, it achieves autonomous recharge without relying on the generator's operating status. Even if the generator stops or fails, the supercapacitor 1 can still recharge autonomously and maintain effective power supply capability. This enables independent emergency power supply for short-term workloads, significantly improving the system's power redundancy and adaptability to multiple scenarios, and meeting the requirements of special vehicles for multiple power source backups.

[0034] Based on a hardware topology with dual independent buses, this embodiment achieves precise power supply authority control. When the grid-connected contactor 2 is closed and the dual buses are running in grid-connected mode, the electrical energy output by the generator flows through the first bus, the closed grid-connected contactor 2, and the second bus, simultaneously supplying power to the long-term working load on the first bus and the short-term working load 11 on the second bus, achieving full load power supply coverage from a single power source. When the grid-connected contactor 2 is open, the two buses are completely electrically isolated, and the electrical energy output by the supercapacitor 1 can only flow within the circuit of the second bus, supplying power only to the short-term working load 11 on the second bus, and cannot supply power to the long-term working load on the first bus at all. This power supply authority control forms a dual guarantee through the physical constraints of the hardware topology and the software constraints of the control logic. It achieves full load power supply coverage by the generator in grid-connected mode, making full use of the generator's continuous power supply capability, and blocks the ineffective discharge path of the supercapacitor 1 in non-grid-connected mode, ensuring that its stored energy is used entirely for peak energy replenishment of short-term impact loads, thereby maximizing energy utilization.

[0035] To ensure the safety of the grid connection process, this embodiment has a first pre-charge circuit 4 connected in parallel across the two ends of the grid connection contactor 2. The trigger condition for this pre-charge circuit is that the generator is enabled. When the generator is enabled and the main power supply is ready, the vehicle controller first starts the first pre-charge circuit 4. The high-voltage power from the first bus is used to pre-charge the second bus and the supporting capacitor at the front end of the short-term working load 11 on the second bus through the first pre-charge circuit 4 until the bus voltage difference across the grid connection contactor 2 meets the preset threshold. After the pre-charge is completed, the controller controls the grid connection contactor 2 to close, completing the grid connection operation of the two buses. In the high-voltage system, the supporting capacitor at the front end of the load is approximately in a short-circuit state when it is not charged. If the grid connection contactor 2 is closed directly, a huge inrush current will be generated at the moment of closing, damaging the contactor, supporting capacitor and other core components. Therefore, the supporting capacitor must be slowly charged through the pre-charge circuit, and the main contactor is closed only after the voltage difference on both sides reaches the standard.

[0036] This embodiment effectively binds the triggering condition of the first pre-charge circuit 4 to the generator enable. Pre-charge is only allowed to start after the main power supply is ready, which avoids the problem of "pre-charge preemptive start" when the power supply is not powered on and the pre-charge contactor is engaged in advance. It also avoids the occurrence of faults such as reverse discharge and high current surge. At the same time, the pre-charge process ensures that the potential of the second bus is basically consistent with that of the first bus before grid connection, further avoiding the impact risk at the moment of grid connection and ensuring the safety of the grid connection process.

[0037] In this embodiment, the long-term working load includes two types: controlled long-term load 8 and uncontrolled long-term load 9. The controlled long-term load 8 is a load that is powered on demand. Its power supply circuit has an independent second distribution contactor 5 connected in series, and the two ends of the second distribution contactor 5 are connected in parallel to a second pre-charge circuit 6. The triggering condition of the second pre-charge circuit 6 is as follows: when the controller receives the working command of the controlled long-term load 8 and the generator is enabled, the controller starts the second pre-charge circuit 6 to pre-charge the supporting capacitor at the front end of the controlled long-term load 8 until the voltage difference across the second distribution contactor 5 meets the preset threshold. After the pre-charge is completed, the controller closes the second pre-charge circuit 6 and simultaneously connects the corresponding second distribution contactor 5 to complete the power-on operation of the load. This setting triggers the pre-charge of the controlled long-term load 8 and is strongly tied to the load's power-on requirements and the generator's ready state. Pre-charging will only be initiated when the load has a clear power-on requirement and the main power supply is ready. This achieves on-demand triggering of load pre-charging, avoiding energy loss caused by invalid pre-charging, and logically avoids pre-charging operations when there is no effective power supply, thus avoiding safety risks such as reverse discharge. At the same time, the pre-charging process eliminates the inrush current at the moment of load power-on, ensuring the safety of powering on long-term working loads.

[0038] For the uncontrolled long-term load 9, which lacks an independent power distribution control switch and is directly connected to the generator output and the first bus, pre-charging cannot be completed through an independent pre-charging circuit. In this embodiment, the generator controller outputs a gradually increasing ramp voltage. During the generator's voltage build-up process, the supporting capacitor at the front end of the uncontrolled long-term load 9 is pre-charged simultaneously. This setup utilizes the generator's controllable voltage build-up characteristics, replacing the need for additional pre-charging circuit hardware. By charging the supporting capacitor with a slowly increasing voltage during voltage build-up, it avoids the large current surge caused by direct full-voltage power-on, ensuring the pre-charging safety of loads without independent power distribution switches. Furthermore, it simplifies the system's hardware topology, eliminating the need for an additional pre-charging circuit for this type of load, thus reducing system hardware complexity and cost.

[0039] For the short-time workload 11, in this embodiment, a third pre-charge circuit 7 is connected in parallel across the third distribution contactor 12 in its power supply circuit. Since the power sources of the short-time workload 11 include a generator in grid-connected mode and a supercapacitor 1 in off-grid mode, the triggering condition of the third pre-charge circuit 7 is set as follows: the controller receives the working command of the short-time workload 11 and meets either the generator being enabled or the supercapacitor 1 being connected to the second bus via an internal contactor. After the triggering condition is met, the controller starts the third pre-charge circuit 7 to pre-charge the supporting capacitor at the front end of the short-time workload 11 until the voltage difference across the third distribution contactor 12 meets the preset threshold. After the pre-charge is completed, the controller closes the third pre-charge circuit 7 and simultaneously connects the corresponding third distribution contactor 12 to complete the power-on operation of the short-time workload. This setting uses "effective power supply readiness" as the core constraint for pre-charge triggering, adapting to two different operating conditions: grid-connected power supply and independent power supply from supercapacitor 1. Regardless of whether the generator is in operation, as long as there is effective power supply connected to the second bus, safe pre-charge and power-on of short-term workloads can be completed, realizing safe power-on control of short-term workloads in all scenarios. At the same time, the pre-charge triggering is strongly bound to the power supply readiness state, eliminating invalid pre-charge when there is no effective power supply, further improving the system's safety.

[0040] In this embodiment, the first pre-charge circuit 4, the second pre-charge circuit 6, and the third pre-charge circuit 7 are all connected in series with current-limiting resistors 10 that match the electrical characteristics of the corresponding circuits. As the core current-limiting component of the pre-charge circuit, the current-limiting resistor 10's core function is to limit the current rise rate of the pre-charge circuit through series impedance, controlling the circuit current during the pre-charge process within a safe range that the high-voltage devices can withstand. This effectively suppresses the inrush current generated during the pre-charge process, preventing damage to supporting capacitors, contactors, high-voltage cables, and other devices caused by large currents, further improving the safety of each pre-charge process and extending the service life of the core high-voltage devices.

[0041] Furthermore, to prevent device damage caused by abnormalities during the pre-charging process, this embodiment includes a timeout protection mechanism for all pre-charging circuits. After the pre-charging circuit starts, the controller times the circuit in real time. If the pre-charging duration exceeds a preset time and the differential pressure condition for pre-charging completion is not reached, the controller immediately shuts down the corresponding pre-charging circuit, stops the power distribution operation of that circuit, and reports a pre-charging fault to the vehicle control system. During pre-charging, problems such as circuit wiring faults, short circuits in the supporting capacitor, or abnormal power output can prevent pre-charging from completing within the normal time. If the pre-charging circuit continues to operate under load, the current-limiting resistor 10 may overheat and even burn out, leading to a high-voltage safety accident. The timeout protection mechanism in this embodiment monitors the pre-charging process in real time using a time threshold. It promptly cuts off the circuit when an abnormality occurs, avoiding the risk of the current-limiting resistor 10 overheating and burning out, and promptly reporting the fault. This facilitates rapid problem location by maintenance personnel, constructing a closed-loop fault protection mechanism for the pre-charging process and improving the reliability and safety of the high-voltage system.

[0042] In this embodiment, the preset access threshold for supercapacitor 1 is set to 5V, the preset differential voltage threshold for grid-connected contactor 2 and each load distribution contactor is set to 10V, and the preset duration for the precharge circuit timeout protection is set to 10 seconds. These parameters are optimal values ​​set based on the rated voltage level of the vehicle-mounted multi-volt high-voltage system, the withstand voltage and current characteristics of the core components, and the RC time constant of the precharge circuit. The 5V access threshold ensures that the voltage difference between the two sides is sufficiently small when supercapacitor 1 is connected to the second bus, completely eliminating the access impact. The 10V differential voltage threshold ensures proper precharge, controlling the inrush current at the moment of closing within a safe range, while avoiding excessively long precharge time and low efficiency due to an excessively small differential voltage threshold. The 10-second timeout protection duration covers the normal precharge time requirements of all precharge circuits and can promptly disconnect the circuit in case of precharge abnormalities, preventing device damage. It is understood that the above parameters can be adaptively adjusted according to the rated voltage level of the system, the capacitance value of the load supporting capacitor, and the electrical characteristics of the pre-charge circuit, all of which fall within the protection scope of this invention.

[0043] The terms “above,” “below,” and “within” as used above include the number itself; the terms “exceeding” and “excluding” do not include the number itself.

[0044] The present invention has been further described above with reference to specific embodiments. However, it should be understood that the specific descriptions herein should not be construed as limiting the substance and scope of the present invention. Various modifications made to the above embodiments by those skilled in the art after reading this specification are all within the scope of protection of the present invention. The various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the embodiments of the present invention will not further describe various possible combinations.

[0045] If the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

Claims

1. A parallel grid control method of a dual high-voltage power supply system, characterized by, Includes the following steps: The system is equipped with physically isolated first and second buses. The first bus is electrically connected to the generator and long-term working load, while the second bus is electrically connected to the supercapacitor and short-term working load. A grid-connected contactor is connected in series between the first and second buses. The first and second buses are selectively electrically connected only through the grid-connected contactor, thereby blocking the power supply path from the supercapacitor to the long-term working load on the first bus in a hardware manner. The controller uses only the generator enable signal and the bus voltage difference across the grid-connected contactor meeting a preset threshold as the sole grid-connected trigger conditions. When both conditions are met, the controller closes the grid-connected contactor to achieve dual-bus grid-connected operation. When the generator enable is invalid, the controller keeps the grid-connected contactor open, and the second bus is powered independently by the supercapacitor for short-term working loads.

2. The method according to claim 1, characterized in that, An internal contactor is provided between the supercapacitor and the second bus. When the controller detects that the voltage of the supercapacitor reaches the rated value and the voltage difference between the supercapacitor and the second bus meets the preset access threshold, it controls the internal contactor to close, so that the supercapacitor is connected to the second bus.

3. The method according to claim 2, characterized in that, The supercapacitor has a built-in charger, which is electrically connected to the vehicle's low-voltage battery. After the low-voltage battery is powered on, the charger converts the electrical energy of the low-voltage battery into high-voltage electrical energy to replenish the supercapacitor until the supercapacitor voltage reaches the rated value. When the supercapacitor voltage is lower than the preset replenishment threshold, the charger automatically starts to replenish the supercapacitor.

4. The method according to claim 1, characterized in that, When the first busbar and the second busbar are connected to the grid, the generator supplies power to both long-term and short-term working loads simultaneously through the first busbar, the closed grid-connection contactor, and the second busbar. When the grid-connection contactor is open, the supercapacitor can only supply power to the short-term working load on the second busbar and cannot supply power to the long-term working load on the first busbar.

5. The method according to claim 1, characterized in that, The grid-connected contactor has a first pre-charge circuit connected in parallel at both ends. The trigger condition for the first pre-charge circuit is that the generator is enabled. When the generator is enabled, the controller first starts the first pre-charge circuit and pre-charges the second bus and short-term working load through the first pre-charge circuit until the bus voltage difference at both ends of the grid-connected contactor meets the preset threshold, and then controls the grid-connected contactor to close.

6. The method according to claim 1, characterized in that, The long-term working load includes a controlled long-term working load, and a second pre-charge circuit is connected in parallel across the two ends of the second distribution contactor of the controlled long-term working load. The trigger condition for the second pre-charge circuit is that the load working command is valid and the generator is enabled. The controller starts the second pre-charge circuit to pre-charge the controlled long-term working load until the voltage difference across the second distribution contactor meets the preset threshold, then closes the second pre-charge circuit and connects the second distribution contactor.

7. The method according to claim 6, characterized in that, The long-duration workload also includes an uncontrolled long-duration workload, which is directly electrically connected to the generator output and pre-charged by a gradually rising ramp voltage output from the generator.

8. The method according to claim 1, characterized in that, A third pre-charge circuit is connected in parallel across the two ends of the third distribution contactor of the short-time working load. The triggering condition for the third pre-charge circuit is that the load working command is valid and the generator is enabled or the supercapacitor is connected to the second bus. The controller starts the third pre-charge circuit to pre-charge the short-time working load until the voltage difference across the third distribution contactor meets the preset threshold, then closes the third pre-charge circuit and connects the third distribution contactor.

9. The method according to any one of claims 5, 6, and 8, characterized in that, A current-limiting resistor is connected in series in the first pre-charge circuit, the second pre-charge circuit, and the third pre-charge circuit to suppress the inrush current during the pre-charge process.

10. The method according to any one of claims 5, 6, and 8, characterized in that, Each precharge circuit is equipped with an overtime protection mechanism. If the precharge duration exceeds the preset time and the precharge completion condition is not met, the controller will close the corresponding precharge circuit, stop power distribution, and report a precharge fault.

Images