New energy automobile film heater and dry burning prevention control method thereof

Abstract

The invention discloses a new energy automobile film heater which is characterized in that a shell is divided into an electrical cabin and an air cabin on one side by a heating cavity, a component is fixed in the electrical cabin, a connector used for connecting a cable with the component is arranged on the side face of the electrical cabin, a heating plate is arranged in the heating cavity, and the air cabin is arranged in the heating cavity. A cooling medium inlet and a cooling medium outlet which are used for medium circulation are formed in the side face of the air cabin, the electrical cabin is covered with an upper cover plate, and the air cabin is covered with a lower cover plate. The NTC temperature sensors arranged in the middle of the cooling medium outlet and the runner of the heater are omitted, the temperature of the cooling medium outlet is judged through real-time high voltage, high-voltage current and a control model, and therefore the product cost is reduced.

Description

TECHNICAL FIELD

[0001] The application relates to the field of battery heating technology of new energy vehicles. BACKGROUND

[0002] To improve the comfort of the passenger compartment and meet the heating requirements of the power battery in a low-temperature environment, a new energy vehicle is usually equipped with a high-voltage heater product, including a resistance wire type, a ceramic sheet type and a film heater. The film heater has the advantages of high heating rate and stable current, and has been widely used in recent years When the film heater is working, the temperature of the heating film can reach more than 350 DEG C. If the cooling medium cannot take away the heat in time, the heating film is in a dry burning state, and the surface of the heating film is at risk of being burned out. The current dry burning protection strategy of the film heater is mainly to configure an NTC temperature sensor for the film heater, and to compare and judge through the collected temperature signal, such as CN202311269249.8. The dry burning protection method provided in the patent CN202410576811.X is to first judge whether the temperature sensor is invalid through the temperature value collected by the temperature sensor, and if it is determined to be invalid, a first duty cycle is output through a preset temperature model, and a dry burning control strategy is generated according to the first duty cycle and a preset duty cycle threshold. The control strategy has improved reliability compared with the single determination based on the temperature value, but the determination process is relatively complex, and the dry burning may not be protected in time.

[0003] Therefore, when designing the product, the heating film needs to be fully protected to avoid dry burning failure. SUMMARY

[0004] The technical problem to be solved by the application is to realize a film heater of a new energy vehicle battery capable of preventing dry burning.

[0005] To achieve the above purpose, the technical scheme adopted by the application is as follows: a film heater of a new energy vehicle, a shell of the film heater is separated into an electrical cabin and an air cabin on one side by a heating cavity, components are fixed in the electrical cabin, a connector for connecting cables and the components is arranged on the side surface of the electrical cabin, a heating plate is arranged in the heating cavity, a cooling medium inlet and a cooling medium outlet for medium circulation are arranged on the side surface of the air cabin, an upper cover plate covers the outside of the electrical cabin, and a lower cover plate covers the outside of the air cabin.

[0006] The heating plate separates the heating cavity and the air cabin, the components in the electrical cabin have an electrical gap and a creepage distance between the upper cover plate and the heating cavity, the air cabin is the space between the lower cover plate and the heating plate, and the distance between the heating plate and the lower cover plate is greater than or equal to 15 mm.

[0007] The air cabin is provided with a breather valve for balancing the pressure change of the air cabin.

[0008] The connector includes a high-voltage connector for connecting a whole vehicle high-voltage power distribution unit and providing direct-current power for the membrane heater, and a low-voltage connector for connecting a whole vehicle low-voltage power and a superior ECU and providing a low-voltage power source for the membrane heater and a signal connection interface for the membrane heater and the superior ECU.

[0009] The components include a low-voltage power module, signal acquisition and processing, a communication module, a high-voltage power module, signal acquisition and processing, and an IGBT driving module, and the components are core components for controlling the membrane heater.

[0010] A dry burning prevention control method for a new energy vehicle membrane heater: 1) Obtain a heating power request; 2) If the temperature T_PCBA of the components is greater than or equal to 100°C and lasts for greater than or equal to 300 ms, calculate the heating membrane temperature by a preset control model; 3) Drive the heating plate to operate according to the calculated heating membrane temperature; 4) Determine whether there is a dry burning fault, if not, return to 2), if yes, execute 5); 5) Reduce the heating power of the heating plate by 10% to 20% and operate for a set time; 6) Drive the heating plate to operate according to the calculated heating membrane temperature; 7) Determine whether there is a dry burning fault, if not, return to 2), if yes, determine that there is a dry burning fault, and shut down the heating plate and report the dry burning fault.

[0011] According to the TCR characteristics of the heating plate, a cooling medium inlet temperature-cooling medium flow rate-high-voltage voltage-high-voltage current-heating power-heating membrane temperature-cooling medium outlet temperature control model is calibrated in advance.

[0012] The way to determine that there is a dry burning fault is that T_membrane is greater than 120°C and lasts for greater than or equal to 500 ms and △T2' / △t2' is greater than △T1' / △t1'.

[0013] When a suspected dry burning fault is determined, the HVH reduces the power to the initial power, and then the power is increased again. When it is diagnosed that the heating membrane temperature T_membrane is greater than 120°C, the temperature rise rates of any two time lengths are represented by △T2' / △t2' and △T1' / △t1' respectively, △T2' / △t2'= (T_t21-T_t20) / (t21-t20); △T1' / △t1'=(T_t11-T_t10) / (t11-t10); In the 5), the heating power of the heating plate is reduced by 10% to 20% and operated until the heating membrane temperature calculated in the 2) is reached, and then lasts for greater than or equal to 3 min.

[0014] This invention eliminates the need for NTC temperature sensors at the heater cooling medium outlet and in the middle of the flow channel. Instead, it determines the cooling medium outlet temperature by using real-time high voltage, high current, and a control model, thereby reducing product costs. Furthermore, by comparing the real-time temperature value of the PCBA temperature sensor with the PCBA temperature threshold, and by making full use of the TCR (temperature coefficient of resistance) characteristics of the heating film itself, combined with the heater's high voltage and current signals and control model, it is possible to accurately determine whether the heater is dry-burning and to perform safe and effective control. Attached Figure Description

[0015] The following is a brief explanation of the content and markings in each of the accompanying drawings in this specification: Figure 1 This is a schematic diagram of the electrical principle of a membrane heater. Figure 2 Flowchart of the anti-dry-burning control logic for membrane heaters; Figure 3 This is a schematic diagram of the main structure of the membrane heater; Figure 4 This is a cross-sectional view of a membrane heater; The markings in the above figures are as follows: 1-Heating chamber, 101-Electrical compartment, 102-Air compartment, 103-Breath valve, 2-Cooling medium outlet, 3-High voltage connector, 4-Low voltage connector, 5-Cooling medium inlet, 6-PCBA, 7-Upper cover plate, 8-Lower cover plate, 9-Heating plate, 10-Sealing ring. Detailed Implementation

[0016] The following description, with reference to the accompanying drawings, details the specific implementation of the present invention, including the shape and structure of each component, the relative positions and connections between the parts, the function and working principle of each part, the manufacturing process, and the operation and use methods, to help those skilled in the art to have a more complete, accurate, and in-depth understanding of the inventive concept and technical solution of the present invention.

[0017] The membrane heater includes a heating chamber 1, an electrical compartment 101, an air compartment 102, a vent valve 103, a cooling medium outlet 2, a high-voltage connector 3, a low-voltage connector 4, a cooling medium inlet 5, a PCBA 6, an upper cover plate 7, a lower cover plate 8, a heating plate 9, and a sealing ring 10. This membrane heater is used to provide heat energy for the passenger compartment and battery pack of new energy vehicles.

[0018] The heating chamber 1 is made of aluminum alloy and engineering plastics (PEEK+GF30, PI+GF30, PBI+GF30, PSU+GF30, PPS+GF30). On the one hand, it provides installation space for PCBA6 and heating plate 9, and on the other hand, it provides a flow field for the cooling medium, transferring the heat energy converted by the heating plate 9 to the place where heat energy is required through the cooling medium. Electrical compartment 101 refers to the space formed by the upper cover plate 7 and the heating cavity 1. PCBA6 is installed in this space, mainly to provide a place for PCBA6 to be completely isolated from the external environment and cooling medium. The electrical clearance and creepage distance between the electrical components of PCBA6 and the surrounding upper cover plate 7 and heating cavity 1 all meet the requirements of electrical safety regulations. The air chamber 102 is a space formed by the lower cover plate 8 and the heating plate 9 installed in the heating cavity 1. The distance between the heating plate 9 and the lower cover plate 8 is ≥15mm. On the one hand, it reduces the amount of heat loss from the heating plate 9 to the environment. On the other hand, it prevents the lower cover plate 8 from getting too hot due to being too close to the heating plate 9, which could burn the surrounding parts of the vehicle. The vent valve 103 is mainly used to balance the pressure changes in the air chamber 102 and reduce the risk of connection failure between the lower cover plate 8 and the heating chamber 1. Cooling medium outlet 2 and cooling medium inlet 5 are located in heating chamber 1 and connected to the internal flow field of heating chamber 1, providing inlet and outlet channels for the cooling medium. High-voltage connector 3 is used to connect to the vehicle's high-voltage power distribution unit to provide DC power to the membrane heater; The low-voltage connector 4 is used to connect the vehicle's low-voltage electrical system and the upper-level ECU. On the one hand, it provides low-voltage power to the membrane heater, and on the other hand, it provides a signal connection interface between the membrane heater and the upper-level ECU. PCBA6 comprises a low-voltage power supply module (low-voltage power filtering, voltage conversion, isolation power supply, etc.), a signal acquisition and processing module (low-voltage power acquisition, cooling medium outlet 2 temperature acquisition), a communication module (LIN or CAN communication), a high-voltage power supply module (voltage conversion, high-voltage area power filtering, etc.), a signal acquisition and processing module (high-voltage acquisition, high-voltage current acquisition, IGBT drive voltage acquisition, IGBT temperature acquisition), and an IGBT drive module (IGBT drive circuit and protection circuit, etc.), and is the core component for controlling the membrane heater.

[0019] The upper cover plate 7 and the lower cover plate 8 are made of aluminum alloy, cold-rolled hot-dip galvanized steel sheet, engineering plastics (PEEK+GF30, PI+GF30, PBI+GF30, PSU+GF30, LCP+GF30, PPS+GF30, etc.). The upper cover plate 7 and the lower cover plate 8 can be connected to the heating cavity 1 by snap-fit ​​+ sealant (two-component silicone rubber sealant, silicone sealant, ceramic-based sealant, organosilicon sealant, etc.) or bolt connection + sealant (two-component silicone rubber sealant, silicone sealant, ceramic-based sealant, organosilicon sealant, etc.).

[0020] like Figure 2 As shown, the anti-dry-burning control method based on the above-mentioned membrane heater includes the following steps: Step 1: In this invention, the temperature sensor at the cooling medium outlet 2 is eliminated. Based on the TCR (temperature coefficient of resistance) characteristics of the heating film itself, a control model (hereinafter referred to as the control model) is calibrated to control the temperature at the cooling medium inlet 5, the cooling medium flow rate, the high voltage, the high voltage current, the heating power, the heating film temperature, and the temperature at the cooling medium outlet 2. The temperature at the cooling medium outlet 2 is calculated and determined by importing the real-time high voltage and high current signals into the control model. Step 2: The ECU receives the membrane heater operation command sent by the superior. Step 3: The membrane heater starts a self-test. If it is normal, proceed to the next step. If the self-test is abnormal, an alarm will be triggered and the system will return to perform another self-test. If the self-test fails after a set number of times (e.g., 3 times), the heating power request will be turned off. Step 4: Use the signal read by the PCBA6 temperature sensor as a preliminary basis for determining whether a dry burning fault has occurred. If the PCBA6 temperature T_PCBA6 ≥ 100℃ and lasts for ≥ 300ms, proceed to the next step if the requirement is met; otherwise, return to the previous step. Step 5: Calculate the heating film temperature (T_film) using the control model, which is the target heating temperature of the heating plate 9. Step 6: During the execution process, it will continuously check whether there is a dry burning situation. If there is a dry burning situation, it needs to continue to check accurately. If there is no dry burning situation, it will return to step 4 and continue to cycle like this. The method for determining dry burning is as follows: T_film > 120℃ and lasts for ≥ 500ms, and the temperature rise rate ΔT2 / Δt2 > ΔT1 / Δt1 for any continuous duration. T_film is the temperature of heating plate 9. If the above requirements are not met, it is judged as a suspected dry burning fault. The membrane heater controller will no longer respond to the heating power increase request from the upper controller, and the control duty cycle will be reduced by 10%-20% until the initial heating power is reached. After stabilizing for ≥ 3 minutes, it will reload and respond to the heating power request from the upper controller. At the same time, it will diagnose the heating membrane temperature and its increase rate. If T_film > 120℃ and lasts for ≥ 500ms, and ΔT2' / Δt2' > ΔT1' / Δt1', it is judged as a dry burning fault. The membrane heater will shut down the power output and send a dry burning fault to the upper controller.

[0021] The dry-burning fault determination strategy of this invention first reduces the power and then increases the power after detecting a suspected dry-burning fault, and determines the fault by the temperature rise rate. This can avoid the situation where the membrane heater cannot continue to work due to misjudgment of dry-burning fault.

[0022] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other occasions without modification, are all within the protection scope of the present invention.

Claims

1. A membrane heater for new energy vehicles, characterized in that: The housing of the membrane heater is divided into an electrical compartment and an air compartment on one side by a heating chamber. The electrical compartment contains fixed components, and the side of the electrical compartment is provided with a connector for connecting cables and components. The heating chamber contains a heating plate, and the side of the air compartment is provided with a cooling medium inlet and a cooling medium outlet for medium circulation. The electrical compartment is covered by an upper cover plate, and the air compartment is covered by a lower cover plate.

2. The new energy vehicle membrane heater according to claim 1, characterized in that: The heating plate separates the heating cavity and the air chamber. The components in the electrical compartment have electrical clearances and creepage distances with the upper cover plate and the heating cavity. The air chamber is the space between the lower cover plate and the heating plate. The distance between the heating plate and the lower cover plate is ≥15mm.

3. The new energy vehicle membrane heater according to claim 2, characterized in that: The air chamber is equipped with a vent valve to balance changes in air chamber pressure.

4. The new energy vehicle membrane heater according to claim 1, 2 or 3, characterized in that: The connector includes a high-voltage connector and a low-voltage connector. The high-voltage connector is used to connect to the vehicle's high-voltage power distribution unit and provide DC power to the membrane heater. The low-voltage connector is used to connect to the vehicle's low-voltage power supply and the upper-level ECU, and provides low-voltage power to the membrane heater and a signal connection interface between the membrane heater and the upper-level ECU.

5. The new energy vehicle membrane heater according to claim 4, characterized in that: The components include a low-voltage power supply module, a signal acquisition and processing module, and a communication module, as well as a high-voltage power supply module, a signal acquisition and processing module, and an IGBT drive module. These components are the core components for controlling the membrane heater.

6. A method for preventing dry burning of a membrane heater in a new energy vehicle, characterized in that: 1) Obtain heating power request; 2) If the temperature of the component T_PCBA is ≥100℃ and lasts for ≥300ms, the temperature of the heating film is calculated using the preset control model; 3) Drive the heating plate to operate according to the calculated heating film temperature; 4) Determine if there is a dry-burning fault; if not, return to step 2); if so, proceed to step 5). 5) Reduce the heating power of the heating plate and continue for the set time; 6) Drive the heating plate according to the calculated heating film temperature; 7) Determine if there is a dry burning fault. If not, return to step 2. If yes, determine that it is a dry burning fault, turn off the heating plate and report the dry burning fault.

7. The method for preventing dry burning according to claim 6, characterized in that: Based on the TCR characteristics of the heating plate, a control model for the cooling medium inlet temperature, cooling medium flow rate, high voltage, high voltage current, heating power, heating film temperature, and cooling medium outlet temperature is calibrated in advance.

8. The method for preventing dry burning according to claim 6, characterized in that: The method to determine if there is a dry burning fault is: T_film > 120℃ and lasts for ≥ 500ms and △T2' / △t2' > △T1' / △t1'.

9. The method for preventing dry burning according to claim 6, characterized in that: In step 5), the heating power of the heating plate is reduced by 10%-20% until the heating film temperature calculated in step 2) is reached, and then maintained for ≥3 minutes.

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