A safe power-on control method for an electric vehicle air conditioning system

Abstract

The application discloses a kind of electric vehicle air conditioning system safety power-on control method, it is related to electric vehicle technical field, comprising the following steps: receiving power-on instruction, disconnect all load switches in air conditioner controller inside;According to multiple different dimensions state parameters, determine whether the current system meets the safety power-on condition;According to the demand closure target load corresponding load switch;According to electrical parameter, judge whether load switch is closed successfully;If all the load switches that need to be closed are closed successfully, feedback power-on is completed, otherwise execute fault response measures.The application obtains multiple different dimensions state parameters for comprehensive judgment, overcomes the defects that prior art only relies on single electrical parameter to judge power-on condition;After closing load switch, electrical parameter is obtained for closed loop verification, overcomes the deficiency that prior art lacks action verification mechanism.Combination of multi-dimensional comprehensive judgment and closed loop verification significantly improves the safety and reliability of system power-on process.

Description

Technical Field

[0001] This invention relates to the field of electric vehicle technology, and in particular to a method for safe power-on control of an electric vehicle air conditioning system. Background Technology

[0002] With the rapid development of the new energy vehicle industry, the safety and reliability of electric vehicle air conditioning systems, as an important component of the vehicle's high-voltage electrical system, are receiving increasing attention. Electric vehicle air conditioning systems typically include a compressor, a PTC heater, an air conditioning controller, and multiple high-voltage relays and electronic switches connected to the controller. When the vehicle is powered on or the air conditioning is turned on, it is necessary to safely and reliably close the switching devices corresponding to each high-voltage load to establish a high-voltage power supply path.

[0003] Currently, power-on control methods for electric vehicle air conditioning systems generally focus on the judgment and control of the pre-charging process. For example, CN108454407A discloses a power-on control method for an electric vehicle air conditioning system including an air conditioning pre-charging resistor. In this method, the air conditioning control panel sends an A / C request signal to the vehicle controller, the vehicle controller sends a pre-charging command to the battery management system, and the battery management system determines whether the pre-charging resistor voltage is greater than 95% of the total voltage. If the pre-charging is complete, the vehicle controller sends a control signal to the battery management system to turn on the air conditioning high voltage and disconnect the pre-charging resistor, and then turn on the compressor.

[0004] It is evident that the core concept of existing technology lies in using a single condition as the basis for power-on determination, treating power-on as an open-loop process executed in a preset sequence, with completion assumed after each step. However, this control method has the following drawbacks: First, current technologies rely solely on a single electrical parameter to determine power-on conditions, failing to conduct comprehensive multi-dimensional verification of the system status. An anomaly in this single signal could lead to misjudgments and pose safety hazards.

[0005] Secondly, existing technology assumes that the relay has been successfully executed after issuing a relay closing command, without actively checking and verifying the actual closing state of the relay contacts. If the relay fails to close reliably due to contact bounce, insufficient driving force, or poor contact, the system will not be able to detect it in time, affecting the normal operation of subsequent loads.

[0006] In summary, existing power-on control methods for electric vehicle air conditioning systems have significant shortcomings in terms of judgment dimensions and action verification. There is an urgent need for a power-on control method that can perform multi-dimensional safety verification and has a closed-loop verification mechanism after the action. Summary of the Invention

[0007] This invention provides a safe power-on control method for an electric vehicle air conditioning system, aiming to solve the safety hazards of existing power-on methods due to the single dimension of power-on condition judgment and the lack of a closed-loop verification mechanism after the action.

[0008] The present invention adopts the following technical solution: A method for safe power-on control of an electric vehicle air conditioning system includes the following steps executed by the air conditioning controller: Step S1: Receive the power-on command and disconnect all load switches inside the air conditioner controller to establish a safe initial state; Step S2: Obtain multiple status parameters in different dimensions. When all status parameters meet the preset conditions, determine that the current system meets the safe power-on conditions. Step S3: According to the system operating mode command, close the load switch corresponding to the target load as needed; Step S4: Obtain the electrical parameters of the load switch, and determine whether the load switch has been successfully closed based on the electrical parameters; Step S5: If all load switches that need to be closed are closed successfully, the feedback power-on is completed; if a load switch fails to close, the fault response measures are executed.

[0009] Furthermore, the status parameters include the on / off state of the external power supply relay and the circuit voltage V. loop Voltage change rate α, controller low-voltage supply voltage V low When the external power supply relay is in the closed state, the circuit voltage V loop Greater than the dynamic power-on voltage threshold V th The voltage change rate α is less than the preset change rate threshold α th Furthermore, if the controller's low-voltage power supply voltage is within the preset range, the system is determined to meet the safe power-on conditions.

[0010] Furthermore, the dynamic power-on voltage threshold V th Equal to the current bus voltage V bus Multiply by the preset scaling factor.

[0011] Furthermore, the preset proportionality coefficient is 90%, and the preset rate of change threshold α th The low-voltage supply voltage V of the controller is 5V / ms. low The preset range is 24V±1V or 12V±1V.

[0012] Furthermore, in step S2, if not all of the aforementioned status parameters meet the preset conditions, the process returns to re-evaluate and accumulates the waiting time. If the accumulated waiting time exceeds the preset timeout threshold, the power-on failure is determined.

[0013] Furthermore, in step S3, the target load includes a compressor and a PTC heater. The load switch corresponding to the compressor is a compressor relay, and the load switch corresponding to the PTC heater is a PTC electronic switch. When it is determined that the current system meets the safe power-on conditions, the compressor relay is directly closed. When it is determined that the current system meets the safe power-on conditions and a PTC heater closing command is received, the PTC electronic switch is closed.

[0014] Furthermore, in step S4, the electrical parameter is the voltage difference ΔV between the input and output terminals of the load switch; before obtaining ΔV, the process also includes: waiting for a preset debouncing time to avoid the contact bounce period of the mechanical relay.

[0015] Furthermore, the preset de-jitter time is 20ms; if the pressure difference ΔV is less than the preset pressure difference threshold ΔV th If the load switch closes successfully, it is determined that the switch has been closed successfully; otherwise, it is determined that the closure has failed.

[0016] Furthermore, in step S4, after the initial determination that a load switch has failed to close, at least one pulse closure retry is performed on the load switch. If the closure still fails after the retry and the number of retries has been reached, the load switch is ultimately determined to have failed to close.

[0017] Furthermore, in step S5, the fault response measure is to report the fault information of the load switch and prohibit the load switch from closing again within the current power-on cycle.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention overcomes the shortcomings of existing technologies that rely solely on a single electrical parameter to determine power-on conditions by comprehensively judging multiple state parameters from different dimensions; it also overcomes the deficiency of existing technologies that lack post-action verification mechanisms by acquiring electrical parameters after closing the load switch. Through the combination of multi-dimensional comprehensive judgment and closed-loop verification, the safety and reliability of the system's power-on process are significantly improved.

[0019] 2. This invention integrates and judges multiple state parameters from different dimensions, such as the closed state of the external power supply relay, the circuit voltage, the voltage change rate, and the low-voltage power supply voltage of the controller, covering the communication layer, the main circuit layer, the pre-charge process layer, and the controller capability layer. This avoids false closing caused by the failure of a single signal, making the determination of safe power-on conditions more comprehensive and reliable.

[0020] 3. After closing the load switch, this invention waits for the debouncing time to avoid the contact bounce period before acquiring the differential pressure for closure status detection, and introduces a pulse retry mechanism to eliminate occasional closure failures. This rigorous detection process effectively improves the accuracy of closure status judgment and avoids misjudgments caused by instantaneous fluctuations. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the hardware structure of the electric vehicle air conditioning system in this invention.

[0022] Figure 2 This is a block diagram illustrating the algorithm principle of the power-on control method in this invention.

[0023] Figure 3 This is a flowchart of the power-on control method in this invention. Detailed Implementation

[0024] Specific embodiments of the present invention will now be described with reference to the accompanying drawings. Many details are described below to provide a comprehensive understanding of the invention; however, those skilled in the art will be able to implement the invention without these details.

[0025] like Figure 1 As shown, this embodiment discloses a safe power-on control method for an electric vehicle air conditioning system. This control method is designed based on common electric vehicle air conditioning systems in the prior art. The electric vehicle air conditioning system includes a vehicle control unit (VCU), a multi-function controller, and an air conditioning system that work together. To clearly introduce the power-on control method later, the circuit structure of the electric vehicle air conditioning system will be described in detail below.

[0026] 1. Vehicle Controller: The VCU communicates with the multi-function controller and the air conditioning controller via the CAN bus to coordinate the high-voltage power-on and power-off sequence of the vehicle.

[0027] 2. Multi-function controller: The multi-function controller is located outside the air conditioning system and is used to draw power from the vehicle's high-voltage battery pack and provide high-voltage power to the air conditioning system according to the instructions of the VCU.

[0028] The all-in-one controller has an external high-voltage power supply relay KM1 inside. KM1 is a mechanical relay. The first terminal of KM1 is connected to the positive terminal of the high-voltage battery pack, and the second terminal of KM1 serves as the high-voltage output terminal connected to the air conditioner controller.

[0029] A pre-charge circuit is connected in parallel across both ends of KM1. This pre-charge circuit consists of a pre-charge resistor R1 and a pre-charge switch connected in series. Before KM1 closes, the pre-charge switch closes first, allowing the external high voltage to slowly charge the downstream capacitor via the pre-charge resistor R1. After pre-charging is complete, KM1 closes, achieving zero-differential voltage closure and preventing surge current impact. The closing and opening of KM1 is controlled by the VCU via CAN communication commands, and its status is sent to the air conditioning controller via CAN messages. When KM1 is closed, the external high-voltage power supply is connected to the air conditioning system; when KM1 is open, the air conditioning system is physically isolated from the high-voltage power supply.

[0030] 3. Air Conditioning System: The air conditioning system includes an air conditioning controller and various high-voltage loads controlled by it. These high-voltage loads include the compressor, the first PTC heater, and the second PTC heater. The air conditioning controller is the core control unit of the air conditioning system. Internally, it contains a microcontroller (MCU), drive circuits, and multiple internal switches connected to the drive circuits. The MCU communicates with the VCU via a CAN bus, receiving air conditioning operating mode commands and KM1 status messages from the VCU, and sending high-voltage power-on requests and fault status information to the VCU. The types, connections, and functions of the internal switches are as follows: (1) Compressor relay KM2: KM2 is a mechanical relay located inside the air conditioner controller. The input terminal of KM2 is connected to the output terminal of KM1, and the output terminal of KM2 is connected to the input terminal of the compressor controller (DCAC controller). The output terminal of the compressor controller is connected to the compressor. A pre-charging resistor R2 is connected in parallel across the two ends of KM2. This pre-charging resistor R2 is used to pre-charge the high-voltage bus capacitor inside the compressor controller before KM2 closes, to avoid surge current generated at the moment KM2 closes. The coil drive signal of KM2 is controlled by the MCU. KM2 is a dedicated switch for the compressor branch, and its closure only provides high-voltage power to the compressor branch. During the power-on process, KM2 closes first regardless of whether the compressor needs to work. Whether the compressor actually runs is determined by the compressor controller later.

[0031] (2) First PTC electronic switch KM3: KM3 is an electronic switch, specifically an IGBT or MOSFET, and is installed inside the air conditioner controller. The input terminal of KM3 is directly connected to the output terminal of KM1, the output terminal of KM3 is connected to the positive terminal of the first PTC heater, and the negative terminal of the first PTC heater is connected to the high-voltage negative bus. KM3 turns on and off by receiving PWM signals or IO level signals from the MCU.

[0032] (3) Second PTC electronic switch KM4: KM4 is an electronic switch, specifically an IGBT or MOSFET, and is located inside the air conditioner controller. The input terminal of KM4 is directly connected to the output terminal of KM1, and the output terminal of KM4 is connected to the positive terminal of the second PTC heater. The negative terminal of the second PTC heater is connected to the high-voltage negative bus. KM4 and KM3 are connected in parallel, each independently controlling one PTC heater to meet different heating power requirements.

[0033] The input terminals of KM2, KM3, and KM4 are all directly connected to the output terminal of KM1, forming three parallel load branches, each powered independently. The negative terminal of each load branch is connected to the high-voltage negative bus, forming a complete current loop.

[0034] (4) Sampling circuit: To monitor the operation status of each switch and the operating status of the load, the air conditioner controller is also connected to a voltage sampling circuit, a current sampling circuit, and a temperature sampling circuit. Each sampling circuit transmits the collected analog signals to the MCU after analog-to-digital conversion, and the MCU executes the power-on control method provided in this embodiment of the invention. Specifically: ① Voltage Sampling Circuit: Four voltage sampling points are set up, located at the input, output, output, and output terminals of KM2, KM3, and KM4 respectively, to collect the voltage signal relative to ground at each location. The input voltage of KM2 serves as the bus voltage and also acts as the common front-end voltage for KM2, KM3, and KM4. The voltage difference at KM2 is obtained by subtracting the output voltage from the input voltage of KM2; the voltage difference at KM3 is obtained by subtracting the output voltage from the input voltage of KM3; and the voltage difference at KM4 is obtained by subtracting the output voltage from the input voltage of KM2.

[0035] ② Current sampling circuit: Three current sampling points are set up, respectively in the first PTC branch, the second PTC branch and the compressor branch, to collect the real-time current of each branch; ③ Temperature sampling circuit: Three temperature sampling points are set up, which are respectively set on the body of compressor relay KM2, first PTC electronic switch KM3 and second PTC electronic switch KM4, to collect the real-time temperature of each switch body.

[0036] like Figure 1-3 As shown, the following describes in detail the safe power-on control method for an electric vehicle air conditioning system provided by the embodiments of the present invention, in conjunction with the above hardware structure.

[0037] The power-on control method provided in this embodiment is executed by a microcontroller (MCU) in the air conditioner controller. The core concept of this method is to upgrade the traditional "open-loop execution" of the power-on process to "closed-loop verification." Specifically, before closing the load switch, a comprehensive safety check is performed using multiple state parameters from different dimensions; after closing the load switch, the electrical parameters of the switch are actively checked to verify whether the closing action was effectively executed. This power-on control method includes the following steps: Step S1: Receive the power-on command and disconnect all load switches inside the air conditioner controller to establish a safe initial state.

[0038] Specifically, the air conditioning controller receives a power-on command. This power-on command can be a system power-on command sent by the vehicle control unit (VCU) via the CAN bus, or a local start signal sent by the air conditioning control panel.

[0039] Upon receiving the power-on command, the air conditioning controller disconnects all internal load switches (KM2, KM3, KM4) to establish a safe initial state. Regardless of the state of each switch before power-on, it is forced back to the open state to ensure that subsequent closing operations begin from a defined and safe starting point.

[0040] Step S2: The air conditioner controller acquires multiple status parameters from different dimensions. When all status parameters meet the preset conditions, it is determined that the current system meets the safe power-on conditions.

[0041] Specifically, the status parameters include the on / off state of the external power supply relay and the circuit voltage V. loop Voltage change rate α, controller low-voltage supply voltage V low The preset conditions for each state parameter are: (1) External power supply relay is in closed state: The status message that the external high voltage power supply relay KM1 is closed is received through CAN communication; (2) Circuit voltage V loop Greater than the dynamic power-on voltage threshold V th V th The current bus voltage V bus Multiply by a preset scaling factor. In this embodiment, the preset scaling factor is 90%, i.e., V th = V bus × 90%; The reason for introducing a dynamic power-on voltage threshold is that the voltage of an electric vehicle's power battery varies significantly with SOC, temperature, and aging. A fixed threshold may never be reached when the battery voltage is low, causing the air conditioner to fail to power on; at high voltages, it may prematurely determine that the battery is qualified, closing the relay before the pre-charge is fully completed. Using 90% of the current actual bus voltage as a dynamic standard, regardless of changes in the battery state, it can accurately determine that the external high voltage has been established and the pre-charge has reached a reasonable level, achieving adaptive safety verification. (3) The voltage change rate α is less than the preset change rate threshold α th : Indicates that pre-charging is complete. In this embodiment, α th The voltage change rate is 5V / ms. The voltage change rate α is calculated through continuous sampling at the output voltage sampling point of KM2 and is used to monitor the voltage ramp-up rate during pre-charging. Pre-charging is jointly completed by the pre-charging resistor R1 across KM1 and the pre-charging resistor R2 across KM2, where α < α th This indicates that the downstream capacitor is nearly fully charged and the voltage is stabilizing. (4) Controller low-voltage power supply voltage V low Within a preset range. In this embodiment, the preset range is 24V±1V or 12V±1V. low The stability of the power supply voltage for the air conditioner controller MCU and drive circuit is a necessary condition for the reliable operation of the relay.

[0042] The four conditions are logically ANDed; if all four are met, the system is deemed to meet the safe power-on conditions. The reason for introducing multi-dimensional comprehensive judgment is that a single condition may lead to misjudgment due to sensor drift, communication interference, or localized faults. For example, relying solely on loop voltage might mistakenly indicate system readiness when CAN communication is interrupted; relying solely on pre-charge completion might result in unreliable relay engagement when the controller's power supply is insufficient. By comprehensively verifying from four dimensions—communication layer, main circuit layer, pre-charge process layer, and controller capability layer—a complete multi-dimensional decision-making evidence chain is constructed, fundamentally avoiding false closures caused by a single signal failure.

[0043] If any status parameter does not meet the preset conditions, the process returns to reacquire all status parameters and accumulates the waiting time. If the accumulated waiting time exceeds the preset timeout threshold (e.g., 500ms), the power-on is deemed a failure, and the process terminates. The timeout mechanism is set to avoid infinite waiting when the external high voltage is not established or the pre-charge circuit fails.

[0044] Step S3: According to the system working mode instructions, close the load switch corresponding to the target load as needed.

[0045] Specifically, after determining that the safe power-on conditions are met, the air conditioning controller closes the load switch corresponding to the target load as needed, according to the system operating mode command. In this embodiment, the target load includes the compressor, the first PTC heater, and the second PTC heater. The load switch corresponding to the compressor is the compressor relay KM2, and the load switches corresponding to the first PTC heater and the second PTC heater are the first PTC electronic switch KM3 and the second PTC electronic switch KM4, respectively.

[0046] When the system is determined to meet safe power-on conditions, the air conditioning controller directly closes KM2. The closing of KM2 is independent of the compressor's operating requirements; regardless of whether the system is currently in cooling, heating, or ventilation-only mode, KM2 closes first to establish a power supply path for the compressor branch. Whether the compressor actually runs is determined by the compressor controller based on subsequent instructions. As a mechanical relay, KM2 requires pre-charging the internal capacitor of the compressor controller through the pre-charging resistor R2 before closing the main contacts to achieve zero-differential-pressure closure.

[0047] When the system is determined to meet safe power-on conditions and a PTC heater closing command is received, the air conditioning controller closes the corresponding KM3 or KM4. The PTC heater is a purely resistive load, and its power-on and power-off are entirely controlled by an electronic switch. The closing command usually originates from the system's heating demand. The closing of KM3 and KM4 is independent of each other and can be controlled independently to meet different heating power requirements. If the system is currently in cooling mode or ventilation-only mode, with no PTC heating demand, then KM3 and KM4 remain open.

[0048] Step S4: Obtain the electrical parameters of the load switch, and determine whether the load switch is successfully closed based on the electrical parameters.

[0049] After closing any load switch, the air conditioner controller obtains the electrical parameters of the load switch and determines whether the load switch was successfully closed based on the electrical parameters.

[0050] The electrical parameter is the voltage difference ΔV between the input and output terminals of the load switch. ΔV = V in - V out V in V is the voltage between the switch input terminal and ground. out This is the voltage between the switch output terminal and ground.

[0051] For KM2, V in V is obtained through the voltage sampling point at the input terminal of KM2. out The voltage is obtained through the output voltage sampling point of KM2. For KM3, V in The voltage is obtained through the sampling point at the input terminal of KM2 (since the input terminals of KM3 and KM2 are both connected to the output terminal of KM1, it is the same point), V. out The voltage is obtained through the output voltage sampling point of KM3. The same applies to KM4.

[0052] Before acquiring ΔV, the air conditioning controller waits for a preset debouncing time to avoid the contact bounce period of the mechanical relay. In this embodiment, the preset debouncing time is 20ms.

[0053] After the de-shaking time has elapsed, the air conditioning controller acquires ΔV and determines whether it is less than the preset differential pressure threshold ΔV. th In this embodiment, ΔV th The value is 1V. If ΔV < ΔV th This indicates that the voltage at the input and output terminals of the switch is almost equal, the contacts have been reliably closed or the electronic switch has been fully turned on, and the load switch is determined to have closed successfully.

[0054] If the initial determination is ΔV≥ΔV thIf the closure fails, the load switch will be retried at least once using a pulse closure mechanism. A pulse closure means the MCU sends another set of closure drive signals to the switch to attempt to close it again. The purpose of the retry is to eliminate misjudgments caused by intermittent factors (such as momentary bouncing of mechanical contacts or instantaneous fluctuations in the drive signal). If ΔV < ΔV after the retry... th If the closure is successful, then the closure is considered successful; if the maximum number of retries has been reached (e.g., 2 times), then ΔV≥ΔV is still considered successful. th If so, the load switch is ultimately determined to have failed to close.

[0055] Step S5: If all load switches that need to be closed are closed successfully, the feedback power-on is completed; if a load switch fails to close, the fault response measures are executed.

[0056] Specifically, based on the judgment result of step S4, this step performs the following processing: If all load switches that need to be closed ultimately fail to close, a power-on failure is reported. The air conditioning controller reports the power-on failure status to the VCU via the CAN bus, prohibiting all load switches from closing again within the current power-on cycle.

[0057] If some load switches close successfully while others ultimately fail to close, a power-on failure is reported. The branches corresponding to the successfully closed load switches are put into normal operation, while the branches corresponding to the failed load switches are prohibited from closing again within the current power-on cycle.

[0058] For any load switch that ultimately fails to close, the air conditioning controller performs the following fault response measures: reports the fault information of the load switch, records the corresponding fault code (DTC), reports the fault code to the VCU via the CAN bus, and illuminates the malfunction indicator light on the instrument panel to alert the driver. The fault type is a poor contact fault, indicating that although the load switch received a closing command, the contacts failed to reliably engage. This load switch is prohibited from being closed again during the current power-on cycle.

[0059] It should be noted that the failure of KM2 closure only affects the compressor branch and does not affect the normal closure of KM3 / KM4 or the activation of the PTC branch; the failure of KM3 or KM4 closure only affects the corresponding PTC branch and does not affect other branches. The closure verification and fault handling of each load switch are carried out independently and do not interfere with each other.

[0060] This concludes a complete power-on control process.

[0061] The power-on control method provided in this embodiment overcomes the shortcomings of existing technologies that rely solely on a single electrical parameter to determine power-on conditions by acquiring multiple state parameters from different dimensions for comprehensive safety verification. It constructs a multi-dimensional decision-making evidence chain from the communication layer, main circuit layer, pre-charging process layer to the controller capability layer. A dynamic power-on voltage threshold is introduced, adaptively adjusting the judgment standard based on the current bus voltage, avoiding misjudgments that may occur under different battery conditions due to fixed thresholds. After closing the load switch, a post-action closed-loop verification is achieved by acquiring the voltage difference for debouncing and then performing a retest, enabling timely detection of latent faults such as poor relay contact. Pulse retry attempts are used to eliminate intermittent closing failures. If the retry fails, the impact range of the closing failure is used to distinguish between successful and failed power-on feedback, and fault codes are recorded for diagnosis. This ensures system safety locking and provides accurate fault location information. This safety mechanism, combining multi-dimensional comprehensive judgment and closed-loop verification, significantly improves the safety and reliability of the electric vehicle air conditioning system during the power-on process.

[0062] The above are merely specific embodiments of the present invention, but the design concept of the present invention is not limited thereto. Any non-substantial modifications made to the present invention using this concept shall be considered as infringing upon the protection scope of the present invention.

Claims

1. A method for safe power-on control of an electric vehicle air conditioning system, characterized in that: This includes the following steps performed by the air conditioning controller: Step S1: Receive the power-on command and disconnect all load switches inside the air conditioner controller to establish a safe initial state; Step S2: Obtain multiple status parameters in different dimensions. When all status parameters meet the preset conditions, determine that the current system meets the safe power-on conditions. Step S3: According to the system operating mode command, close the load switch corresponding to the target load as needed; Step S4: Obtain the electrical parameters of the load switch, and determine whether the load switch is successfully closed based on the electrical parameters; Step S5: If all load switches that need to be closed are closed successfully, the feedback power-on is completed; if a load switch fails to close, the fault response measures are executed.

2. The method for safe power-on control of an electric vehicle air conditioning system as described in claim 1, characterized in that: The status parameters include the on / off state of the external power supply relay and the circuit voltage V. loop Voltage change rate α, controller low-voltage supply voltage V low When the external power supply relay is in the closed state, the circuit voltage V loop Greater than the dynamic power-on voltage threshold V th The voltage change rate α is less than the preset change rate threshold α th Furthermore, if the controller's low-voltage power supply voltage is within the preset range, the system is determined to meet the safe power-on conditions.

3. The method for safe power-on control of an electric vehicle air conditioning system as described in claim 2, characterized in that: The dynamic power-on voltage threshold V th Equal to the current bus voltage V bus Multiply by the preset scaling factor.

4. The method for safe power-on control of an electric vehicle air conditioning system as described in claim 3, characterized in that: The preset proportional coefficient is 90%, and the preset rate of change threshold α th The low-voltage supply voltage V of the controller is 5V / ms. low The preset range is 24V±1V or 12V±1V.

5. The method for safe power-on control of an electric vehicle air conditioning system as described in claim 1, characterized in that: In step S2, if not all of the aforementioned status parameters meet the preset conditions, the process returns to re-evaluate and accumulates the waiting time. If the accumulated waiting time exceeds the preset timeout threshold, the power-on failure is determined.

6. The method for safe power-on control of an electric vehicle air conditioning system as described in claim 1, characterized in that: In step S3, the target load includes a compressor and a PTC heater. The load switch corresponding to the compressor is a compressor relay, and the load switch corresponding to the PTC heater is a PTC electronic switch. When it is determined that the current system meets the safe power-on conditions, the compressor relay is closed directly; When it is determined that the current system meets the safe power-on conditions and a PTC heater closing command is received, the PTC electronic switch is closed.

7. The method for safe power-on control of an electric vehicle air conditioning system as described in claim 1, characterized in that: In step S4, the electrical parameter is the voltage difference ΔV between the input and output terminals of the load switch; Before obtaining ΔV, the process also includes waiting for a preset debouncing time to avoid the contact bounce period of the mechanical relay.

8. The method for safe power-on control of an electric vehicle air conditioning system as described in claim 7, characterized in that: The preset de-jitter time is 20ms; if the pressure difference ΔV is less than the preset pressure difference threshold ΔV th If the load switch closes successfully, it is determined that the switch has been closed successfully; otherwise, it is determined that the closure has failed.

9. The method for safe power-on control of an electric vehicle air conditioning system as described in claim 1, characterized in that: In step S4, after a load switch fails to close for the first time, at least one pulse closure retry is performed on the load switch. If the closure still fails after the retry and the number of retries has been reached, the load switch is finally determined to have failed to close.

10. The method for safe power-on control of an electric vehicle air conditioning system as described in claim 1, characterized in that: In step S5, the fault response measure is to report the fault information of the load switch and prohibit the load switch from closing again within the current power-on cycle.

Images