Dry burning control method for film heater of new energy vehicle

Abstract

A dry burning control method for a film heater of a new energy vehicle. Three water temperature sensors located at different positions are arranged in a film heater (2) having a film heating plate (1), all the water temperature sensors are connected into a same control system, and on the basis of feedback signals of the three water temperature sensors, the control system conducts dry burning fault diagnosis and conducts corresponding treatment on the basis of diagnosis content. According to the control method, when the film heater undergoes dry burning, in the shortest time, on the basis of the feedback signals of the water temperature sensors, the control system determines to cut off a high-voltage circuit of the heater, so that the dry burning of the film heater is effectively prevented, and the dry burning problem is solved from the control source of the heater; in addition, the detection and control modes are reasonable and effective, and detection information is subjected to specific processing such that information detection is accurate, thereby avoiding the problem of false alarm caused by information detection errors, and greatly improving the use reliability.

Description

A new energy vehicle membrane heater anti-dry burning control method Technical Field

[0001] The present invention relates to a thermal management system for a water heater of a new energy vehicle, and in particular to a dry-burning prevention control method for a membrane heater of a new energy vehicle. Background Art

[0002] At present, the water heating method of the air-conditioning heater of new energy vehicles mainly includes two types of heating elements, PTC heating sheets or membrane heating plates. The heating elements are arranged in the liquid flow channel of the component, and the heat is brought to the heat exchanger in the air outlet channel by circulating heated liquid. The air flows directly through the heat exchanger and is heated before being blown into the car cabin. Among them, the membrane heater has the characteristics of high heat exchange efficiency, small size, and light weight due to its simple structure and few heat exchange interfaces. It has the advantages of stable resistance, no power attenuation, and low thermal capacity and thermal resistance. Its electrical performance of good controllability and no starting current shock is obviously better than PTC heating. However, its disadvantage is that the membrane heating plate has poor resistance to dry burning. In the absence of protective measures, the surface temperature of the membrane heating plate will reach more than 500°C after 10S, causing damage to the membrane heating plate circuit and the risk of membrane explosion, thereby losing the heater function. Even if there are technical measures for detection using temperature sensors, due to the limitations of the equipment structure, it is easy for the temperature sensor to generate erroneous detection information, and reliable temperature detection cannot be effectively achieved.

[0003] Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a new energy vehicle membrane heater anti-dry burning control method that can accurately detect information and thus effectively prevent the membrane heater from dry burning.

[0005] In order to solve the above technical problems, the new energy vehicle membrane heater anti-dry burning control method of the present invention arranges three water temperature sensors at different positions in a membrane heater with a membrane heating plate and connects each water temperature sensor to the same control system. The feedback signals of the three water temperature sensors enable the control system to make a dry burning fault diagnosis and perform corresponding processing according to the diagnosis content.

[0006] The film heater is provided with a water inlet and a water outlet, and the water temperature sensor includes a water inlet sensor arranged at the water inlet of the film heater, a water outlet sensor arranged at the water outlet of the film heater, and an intermediate sensor arranged at the middle position of the inner end of the film heater.

[0007] The film heating plate is provided with a film temperature sensor for monitoring the temperature of the film heating plate. The film temperature sensor is also connected to the control system.

[0008] The diagnosis content of the control system is dry-burn fault judgment and dry-burn fault recovery.

[0009] The dry-boiling fault determination condition is set as intermediate water temperature minus outlet temperature and intermediate water temperature minus inlet water temperature greater than 3°C, lasting for 200-700ms.

[0010] The time for fault determination is set to 0.1-1s; the actual heating power request of the film heater is greater than 200W.

[0011] The dry-burn fault recovery condition is set as the temperatures of the three water temperature sensors are all less than 70°C, the temperature difference between the three water temperature sensors is less than 2.5°C, the first protection time is 10-20S, and the protection time for continuous fault detection is N*(10-20)S. After ten consecutive times, the fault is locked and the control system needs to be powered on again to clear the fault.

[0012] The monitoring temperature of the film temperature sensor is set to 90-100°C. When the monitored film temperature exceeds the set temperature, it is determined to be a dry burning fault.

[0013] The advantages of the present invention are:

[0014] When the membrane heater burns dry, the control system makes a judgment in the shortest possible time through the feedback signal of the water temperature sensor and cuts off the power to the high-voltage circuit of the heater, thereby effectively preventing the membrane heater from burning dry and solving the dry burning problem from the control source of the heater. In addition, its detection and control methods are reasonable and effective. Through specific processing of various detection information, the information detection is accurate, avoiding the false alarm problem caused by information detection errors, and greatly improving the reliability of use. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] FIG1 is a schematic structural diagram of a film heater according to the present invention;

[0016] FIG2 is a schematic diagram of the arrangement structure of the water temperature sensor in the present invention. DETAILED DESCRIPTION

[0017] The anti-dry burning control method of the new energy vehicle film heater of the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0018] As shown in the figure, the anti-dry burning control method of the new energy vehicle film heater of the present invention is achieved by arranging three water temperature sensors at different positions in a film heater 2 having a film heating plate 1 and connecting each water temperature sensor to the same control system. As can be seen from Figure 2, the film heater 2 is provided with a water inlet 3 and a water outlet 4, and the water temperature sensors include a water inlet sensor 5 arranged at the water inlet of the film heater, a water outlet sensor 6 arranged at the water outlet of the film heater, and an intermediate sensor 7 arranged at the middle position of the inner end of the film heater. Through the feedback signals of the water inlet sensor 5, the water outlet sensor 6 and the intermediate sensor 7, the control system makes a dry burning fault diagnosis and performs corresponding processing according to the diagnosis content.

[0019] Among them, the diagnosis content of the control system is dry-burning fault judgment and dry-burning fault recovery. The judgment condition of dry-burning fault is set as the intermediate water temperature - the outlet temperature and the intermediate water temperature - the inlet water temperature is greater than 3°C, lasting 200-700ms, preferably 500ms, and the time for dry-burning fault judgment is set to 0.1-1S, preferably 0.5S; the actual heating power request of the membrane heater is greater than 200W, and the dry-burning fault recovery condition is set as the temperatures of the three water temperature sensors are all less than 70°C, and the temperature difference between the three water temperature sensors is less than 2.5°C. The first protection time is 10-20S, preferably 15S, and the protection time for continuous fault detection is N*(10-20)S (for example: when the first protection time is 15S, the protection time for continuous fault detection is N*15S). After ten consecutive times, the fault is locked, and the control system needs to be powered on again to clear the fault. Fault handling: turn off the IGBT, stop power output, and report the dry-burning fault.

[0020] Furthermore, a film temperature sensor 8 for monitoring the temperature of the film heating plate can be provided on the film heating plate 2. The film temperature sensor 8 is also connected to the control system. The monitoring temperature of the film temperature sensor 8 is set to 90-100°C. When the film temperature is detected to exceed the set temperature, it is determined to be a dry burning fault.

[0021] Its working principle is:

[0022] In the enclosed space of the water chamber of the heater 2, the temperature of the membrane heating plate 1 rises. Under the normal working condition of the membrane heater, the water temperature of the water inlet sensor is less than 2-3, and the water temperature of the intermediate water temperature sensor is less than the water temperature of the water outlet sensor. When the membrane heater is dry-burned, the temperature of the intermediate water temperature sensor rises the fastest, followed by the water inlet sensor and the water outlet sensor. Through the temperature rise difference of the three water temperature sensors, this characteristic is utilized to perform judgment logic through the control system (controller). In addition, in order to prevent individual failure of the three water temperature sensors, the main body temperature of the membrane heating plate is monitored by the set membrane temperature sensor. When the temperature exceeds a specified temperature, the controller is judged logically to achieve a double anti-dry-burning function.

[0023] Taking the preferred numerical value as an example, during the application process, when a dry-burning fault occurs in the membrane heater, the three water temperature sensors arranged in the membrane heater report the temperature, and the controller makes a judgment within 0.5S to detect whether the water temperature of the intermediate water temperature sensor minus the water temperature of the water outlet sensor and the water temperature of the 2-3 intermediate water temperature sensors minus the water temperature of the water inlet sensor exceeds 3°C. For example: the water temperature of the water inlet sensor is 40°C; the water temperature of the intermediate water temperature sensor is 50°C; the water temperature of the water outlet sensor is 45°C; that is: 50°C-45°C=5°C and 50°C-40°C=10°C, 5°C and 10°C>3°C, the membrane heating controller determines it as a dry-burning fault, turns off the IGBT in the control circuit, and stops power output.

[0024] In addition, under normal circumstances, the temperature of the heating plate is below 100°C. When the membrane temperature exceeds 100°C, the control system determines it as a dry-burning fault, turns off the IGBT in the control circuit, and stops power output.

Claims

1. A method for preventing dry burning of a new energy vehicle membrane heater, characterized in that: By arranging three water temperature sensors at different positions in a film heater (2) having a film heating plate (1) and connecting each water temperature sensor to the same control system, the control system makes a dry-burning fault diagnosis through feedback signals from the three water temperature sensors and performs corresponding processing according to the diagnosis content.

2. The method for preventing dry burning of a new energy vehicle film heater according to claim 1, characterized in that: The membrane heater (2) is provided with a water inlet (3) and a water outlet (4), and the water temperature sensor comprises a water inlet sensor (5) arranged at the water inlet of the membrane heater, a water outlet sensor (6) arranged at the water outlet of the membrane heater, and an intermediate sensor (7) arranged at the middle position of the inner side end of the membrane heater.

3. The method for preventing dry burning of a new energy vehicle film heater according to claim 2 is characterized in that: The film heating plate (2) is provided with a film temperature sensor (8) for monitoring the temperature of the film heating plate. The film temperature sensor (8) is also connected to the control system.

4. The method for preventing dry burning of a new energy vehicle film heater according to claim 2 is characterized in that: The diagnosis content of the control system is dry-burning fault judgment and dry-burning fault recovery.

5. The method for preventing dry burning of a new energy vehicle film heater according to claim 4 is characterized in that: The judgment condition for the dry-burning fault is set as the intermediate water temperature-the water outlet temperature and the intermediate water temperature-the inlet water temperature are greater than 3°C and last for 200-700ms.

6. The method for preventing dry burning of a new energy vehicle film heater according to claim 5 is characterized in that: The time for fault determination is set to 0.1-1S; the actual heating power request of the film heater is greater than 200W.

7. The method for preventing dry burning of a new energy vehicle film heater according to claim 4, 5 or 6, characterized in that: The dry-burning fault recovery condition is set as the temperatures of the three water temperature sensors are all less than 70°C, the temperature difference between the three water temperature sensors is less than 2.5°C, the first protection time is 10-20S, and the protection time for continuous fault detection is N*(10-20)S. After ten consecutive times, the fault is locked and the control system needs to be powered on again to clear the fault.

8. The method for preventing dry burning of a new energy vehicle film heater according to claim 7, characterized in that: The monitoring temperature of the film temperature sensor (8) is set to 90-100°C, and when the monitored film temperature exceeds the set temperature, it is determined to be a dry burning fault.

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