Automobile air-conditioning PTC electric heater dry burning protection control system and control method

Abstract

The present invention discloses a PTC electric heater dry-burn protection control system for an automotive air conditioner. The control system includes an automotive air conditioner controller, an I / O input terminal of the automotive air conditioner controller connected to a PTC electric heater, a PTC temperature sensor disposed on the surface of the PTC electric heater, and the automotive air conditioner controller electrically connected to a PTC high-voltage contactor, a heating and cooling damper actuator, a blower speed control module, a mode damper actuator, a circulation damper actuator, and an instrument panel alarm. The PTC electric heater dry-burn protection control method of the present invention has good feasibility, is more efficient, has a streamlined operation process, and shortens the controller response time. It solves the problems of existing dry-burn protection methods such as long response time, poor effectiveness, and high cost.

Description

Technical Field

[0001] The present invention belongs to the technical field of pure electric vehicle air conditioners, and relates to a dry-burning protection control system for a PTC electric heater in an automobile air conditioner, and also relates to a dry-burning protection control method for a PTC electric heater in an automobile air conditioner. Background Art

[0002] Currently, the air conditioning and heating systems of A00-class pure electric vehicles mostly use air-heating PTC heaters. When heating, the PTC heater uses a high-voltage contactor to switch the PTC's high-voltage power supply on and off, controlled by the air conditioning controller. The high-voltage contactor's voltage is high when it's energized and disconnected, generating arcing during the disconnection process. This limits the number of times the high-voltage contactor can be switched on and off. After a certain number of cycles, contact adhesion can occur, causing uncontrolled switching of the PTC heater's circuit. This can lead to the PTC heater's dry-burning risk, softening or even burning the plastic casing surrounding the PTC, posing significant risks and potential hazards. Existing dry-burn protection methods typically utilize temperature control instruments such as thermocouples, infrared temperature sensors, and thyristors, which require high precision and are costly. Alternatively, they employ complex logic processing. The controller's response time to the fault directly impacts the final resolution of the fault. The logic processing also detects the maximum operating current during the PTC dry-burn event, increasing the controller's processing time. Summary of the Invention

[0003] An object of the present invention is to provide a dry-burn protection control system for a PTC electric heater in an automobile air conditioner, so as to solve the problems of long response time, poor effect and high cost of existing dry-burn protection methods.

[0004] Another object of the present invention is to provide a dry-burn protection control method for a PTC electric heater in an automobile air conditioner.

[0005] One technical solution adopted by the present invention is a dry-burning protection control system for a PTC electric heater of an automobile air-conditioning system, which includes an automobile air-conditioning controller, wherein the I / O input terminal of the automobile air-conditioning controller is connected to the PTC electric heater, a PTC temperature sensor is arranged on the surface of the PTC electric heater, and the automobile air-conditioning controller is electrically connected to a PTC high-voltage contactor, a heating and cooling air door actuator, a blower speed control module, a mode air door actuator, a circulation air door actuator, and an instrument panel alarm.

[0006] The present invention is also characterized in that:

[0007] The PTC temperature sensor uses an NTC temperature sensor.

[0008] Another technical solution adopted by the present invention is a method for controlling a dry-burn protection of a PTC electric heater for an automobile air conditioner, which adopts a dry-burn protection control system for a PTC electric heater for an automobile air conditioner, and is specifically implemented in the following steps:

[0009] Step 1: The PTC temperature sensor collects the temperature value and transmits it to the car air conditioning controller;

[0010] Step 2: The automobile air-conditioning controller collects the current temperature value of the PTC temperature sensor and performs dry-burning mode determination processing;

[0011] Step 3: After entering the dry-heating mode, the automobile air-conditioning controller collects the current temperature value of the PTC temperature sensor and performs dry-heating protection mode judgment processing.

[0012] The present invention is also characterized in that:

[0013] The specific process of step 1 is to turn on the car air conditioning heating mode normally, and all the circuits of the pure electric vehicle air conditioning are in normal state. The PTC temperature sensor collects the temperature value of the surface of the PTC electric heater in real time as the input of the car air conditioning controller, and feeds it back to the car air conditioning controller in real time.

[0014] In step 2, the specific process of determining whether to enter the dry-burning mode is as follows: preset temperature values A and B are preset in the automobile air-conditioning controller, A is not greater than B, and the preset value A is set to the maximum temperature allowed by the PTC temperature sensor when the automobile air-conditioning is in heating condition and the PTC electric heater is working normally; when the current temperature value collected by the PTC temperature sensor is greater than the preset value A, the automobile air-conditioning controller sends an instruction, the PTC high-voltage contactor stops working, and enters the dry-burning mode. When the temperature value is no greater than the preset value A, the instruction stops sending after the dry-burning mode is executed.

[0015] In step 3, the specific process of judging the entry into the dry-burning protection mode is as follows: when the current temperature value collected by the PTC temperature sensor is greater than the preset value B, the automobile air-conditioning controller is forced to enter the dry-burning protection mode, and the automobile air-conditioning controller sends an instruction to control the cooling and heating air door actuators to run to the full warm position; the blower speed control module controls the blower air volume to be at the maximum wind speed, the mode air door actuator runs to the maximum defrost mode, and the circulation air door actuator is in the external circulation mode instruction; again judge whether the current temperature value collected by the PTC temperature sensor is greater than the preset value B. When it is greater than the preset value B, the instrument panel alarm flashes and displays the PTC fault mark accompanied by an alarm sound as a sign of the end of the process; otherwise, the air conditioner returns to the state before the dry-burning protection. At this time, the dry-burning protection mode does not exit until the current temperature value collected is no greater than the preset value B.

[0016] The input of the automobile air conditioning controller is to collect the current temperature value of the PTC in real time through the NTC temperature sensor arranged on the surface of the pure electric vehicle's PTC electric heater. The NTC temperature sensor is connected to the signal input terminal and GND external pins A1 and A2 of the automobile air conditioning controller through a two-port connector with a length of 310mm.

[0017] In step 1, the car air conditioning controller converts the collected temperature analog value in real time through the RT conversion formula, and calculates the resistance value corresponding to different temperatures, thereby obtaining different currents I generated between the two pins A1 and A2. A1A2 ;

[0018] R t =R0*exp[C(1 / (T1)-1 / (T0))] (1)

[0019] In formula (1), R t is the resistance of the thermistor to be determined at temperature T1; R0 is the known nominal resistance of the thermistor at temperature T0; C is the thermal sensitivity index of the thermistor, usually 3270; exp is the nth power of the known e; T1 and T0 are K degrees, that is, Kelvin degrees Celsius, K degrees = absolute temperature 273.15 + degrees Celsius, which are known quantities.

[0020] The beneficial effects of the present invention are that the automotive air conditioner PTC electric heater dry-burn protection control system does not require major modifications to existing vehicle air conditioner structures, has a simple hardware layout, and is highly compatible with air conditioner controllers. It can effectively shorten the controller's response time to a fault, ultimately resolving the fault. It is universally applicable to pure electric vehicle air conditioners, maximizes PTC operational safety, offers high reliability, effectively prevents dry-burning, and protects the safety of people, vehicles, and property. It is easy, efficient, and cost-effective to implement, making it suitable for industrial production applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the structure of the dry-burning protection control system for the automobile air-conditioning PTC electric heater of the present invention;

[0022] Figure 2 This is a flow chart of a dry-burning protection control method for a PTC electric heater for an automobile air conditioner according to the present invention;

[0023] Figure 3 RT characteristic curves of the embodiment of the present invention with the same B value and different resistance values;

[0024] Figure 4 1 is an RT characteristic curve diagram of an embodiment of the present invention with different B values and the same resistance value.

[0025] In the figure, 1. Automobile air conditioning controller, 2. PTC temperature sensor, 3. PTC electric heater, 4. PTC high-voltage contactor, 5. Heating and cooling air door actuator, 6. Blower speed control module, 7. Mode air door actuator, 8. Circulation air door actuator, 9. Instrument panel alarm. DETAILED DESCRIPTION

[0026] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] The present invention provides a PTC electric heater dry burning protection control system for automobile air conditioners. The structure is as follows: Figure 1 As shown, it includes an automobile air-conditioning controller 1, the I / O input end of the automobile air-conditioning controller 1 is connected to the PTC electric heater 3, the surface of the PTC electric heater 3 is arranged with a PTC temperature sensor 2, and the automobile air-conditioning controller 1 is electrically connected to a PTC high-voltage contactor 4, a heating and cooling air door actuator 5, a blower speed control module 6, a mode air door actuator 7, a circulation air door actuator 8, and an instrument panel alarm 9.

[0028] The PTC temperature sensor 2 is an NTC temperature sensor, which is used to collect the surface temperature of the PTC electric heater 3 in real time.

[0029] The present invention is a method for controlling the dry burning protection of the PTC electric heater of the air conditioner of a pure electric vehicle. The process is as follows: Figure 2 As shown, the implementation is carried out according to the following steps:

[0030] Step 1: The PTC temperature sensor 2 collects the temperature value and transmits it to the automobile air conditioning controller 1;

[0031] The specific process of step 1 is as follows: the car air conditioning heating mode is normally turned on, and all the circuits of the pure electric vehicle air conditioning are in normal state. The PTC temperature sensor 2 collects the temperature value of the surface of the PTC electric heater 3 in real time as the input of the car air conditioning controller 1, and feeds it back to the car air conditioning controller 1 in real time;

[0032] The input of the automobile air conditioning controller 1 is to collect the current temperature value of the PTC in real time through the NTC temperature sensor arranged on the surface of the pure electric vehicle PTC electric heater 3. The NTC temperature sensor is connected to the signal input terminal and GND external pins A1 and A2 of the automobile air conditioning controller 1 through a two-port connector with a length of 310mm.

[0033] The automobile air-conditioning controller 1 converts the collected temperature analog value in real time through the RT conversion formula, and calculates the resistance value corresponding to different temperatures through formula (1), thereby obtaining the different currents I generated between the two pins A1 and A2. A1A2 ;

[0034] R t =R0*exp[C(1 / (T1)-1 / (T0))] (1)

[0035] In formula (1), R tis the resistance of the thermistor to be determined at temperature T1; R0 is the known nominal resistance of the thermistor at temperature T0; C is the thermal sensitivity index of the thermistor, usually 3270; exp is the nth power of the known e; T1 and T0 are K degrees, that is, Kelvin degrees Celsius, K degrees = absolute temperature 273.15 + degrees Celsius, which are known quantities.

[0036] Step 2: the automobile air-conditioning controller 1 collects the current temperature value of the PTC temperature sensor 2 and performs a dry-burning mode determination process;

[0037] In step 2, the specific process of determining whether to enter the dry-heating mode is as follows: preset temperature values A and B are preset in the automobile air-conditioning controller 1, A is not greater than B, and the preset value A is set to the maximum temperature allowed by the PTC temperature sensor 2 when the automobile air-conditioning is in the heating condition and the PTC electric heater 3 is working normally; when the current temperature value collected by the PTC temperature sensor 2 is greater than the preset value A, the automobile air-conditioning controller 1 sends an instruction, the PTC high-voltage contactor 4 stops working, and enters the dry-heating mode. When the temperature value is no greater than the preset value A, the sending stops after the dry-heating mode is completed;

[0038] Step 3: After entering the dry-heating mode, the automobile air-conditioning controller 1 collects the current temperature value of the PTC temperature sensor 2 and performs dry-heating protection mode determination processing;

[0039] In step 3, the specific process of judging the entry into the dry-burning protection mode is as follows: when the current temperature value collected by the PTC temperature sensor 2 is greater than the preset value B, the automobile air-conditioning controller 1 is forced to enter the dry-burning protection mode, and the automobile air-conditioning controller 1 sends an instruction to control the heating and cooling air door actuator 5 to run to the full warm position; the blower speed control module 6 controls the blower air volume to be at the maximum wind speed, the mode air door actuator 7 runs to the maximum defrost mode, and the circulation air door actuator 8 is in the external circulation mode instruction; again judge whether the current temperature value collected by the PTC temperature sensor 2 is greater than the preset value B. When it is greater than the preset value B, the instrument panel alarm 9 flashes and displays the PTC fault mark at the same time as the alarm sound as a sign of the end of the process; otherwise, the air conditioner returns to the state before the dry-burning protection. At this time, the dry-burning protection mode does not exit until the current temperature value collected is not greater than the preset value B.

[0040] An embodiment of the dry-burning protection control method of the PTC electric heater of the pure electric vehicle air conditioner of the present invention is to use an NTC temperature sensor arranged at the center of the outer surface of the electric heating PTC of the A00-class pure electric vehicle to collect the current temperature value of the PTC in real time: when the air conditioner is in heating condition and the PTC electric heater 3 is working normally, the maximum temperature allowed by the PTC temperature sensor 2, the temperature preset value A is 80℃, according to the RT table, if the resistance R between the A1 and A2 pins is A1A2If the resistance is less than 1.211kΩ, the left endpoint of the resistance range [1.211kΩ, 1.288kΩ], then the PTC high-voltage power supply terminal will be sticking, and the controller will enter the dry-boil protection mode and execute the dry-boil protection procedure. Otherwise, the actuators and electrical appliances of the air conditioner will maintain their original operating status.

[0041] The automobile air-conditioning controller 1 executes a PTC high-voltage contactor 4 stop-operation instruction, disconnecting the PTC high-voltage power supply terminal;

[0042] According to the RT table, the temperature preset value B is 100℃. A1A2 When it is still greater than the right endpoint 0.7014kΩ of the resistance range [0.6514kΩ, 0.7014kΩ] and less than the left endpoint 1.211kΩ of the resistance range [1.211kΩ, 1.288kΩ], 0.7014kΩ<R A1A2 <1.211k, that is 80℃<T A1A2 ℃<100℃, the automobile air-conditioning controller 1 sends the PTC high-voltage contactor 4 a stop working instruction in a cycle until R A1A2 When the resistance value is greater than the end point of the resistance range, 1.288kΩ, that is, the PTC temperature value is lower than 80°, the execution of the instruction in step 1 is stopped;

[0043] When R A1A2 When the resistance is less than the resistance range [0.6514kΩ, 0.7014kΩ], that is, less than the left endpoint 0.6514kΩ of the temperature preset value B of 100°C, the human-machine interaction function is disabled. The forced dry-burn protection program of the automobile air-conditioning controller 1 causes the DC servo motor in the heating and cooling door actuator to run to point P1 (17°±2°) for the full heating door position, the maximum blower speed is 2000rpm, the DC servo motor in the mode door actuator to run to point P5 (139°±3°) for the defrost mode, and the DC servo motor in the circulation door actuator to run to point P2 (23°±3°) for the external circulation mode; 10 seconds after the execution is completed, if R A1A2 When it is still less than the endpoint value of 0.6514kΩ, the automobile air conditioning controller 1 sends a low-level signal to keep the PTC fault warning light on, which serves as the end mark of the forced dry-burning protection program. A1A2 The resistance value is greater than the end point of the resistance range 1.288kΩ, otherwise the forced dry-burn protection program will continue to run in a loop. In this case, the driver needs to stop the car immediately and turn off the power, and contact maintenance personnel in time for treatment.

[0044] In this embodiment, the dry-burning protection mode simulation experiment is used to verify the results: a dry-burning experiment simulation of the PTC electric heater 3 is carried out in a simulation laboratory, and a RT performance comparison experiment of three NTC temperature sensors is carried out using the control variable method to verify the dry-burning protection control method of the PTC electric heater 3, such as Figure 3As shown, B1, B2, and B3 are the thermal sensitivity indexes of the NTC temperature sensor. If the B value of the NTC thermistor is kept constant and kept at 25°C, that is, B1=B2=B3, its resistance value is R' 25 >R 25 >R” 25 ,like Figure 4 As shown, only two NTC temperature sensors with the same B value are selected, and the experimental curve yields R 25(1) =R 25(2) At the same temperature, the NTC temperature sensor has a smaller B value. The PTC electric heater dry-burning protection control method of the present invention has good feasibility, higher efficiency, streamlined operation, and shortens the controller's response time by 23%.

[0045] In the automotive air conditioner of the present invention, when the PTC electric heater 3 is operating normally under heating conditions, the PTC temperature sensor 2 inputs the collected data into the automotive air conditioner controller 1. When the temperature value collected by the automotive air conditioner controller 1 exceeds a preset value A, which is the maximum temperature allowed by the PTC temperature sensor 2, the automotive air conditioner controller 1 indicates that the PTC electric heater 3 is in a faulty state. The automotive air conditioner controller 1 sends a command to disconnect the PTC high-voltage power supply, causing the PTC electric heater 3 to stop operating. When the temperature collected by the automotive air conditioner controller 1 exceeds a preset value B, that is, the value of the PTC temperature sensor 2 continues to rise for a certain period of time, it indicates that the PTC electric heater 3 is still operating. To prevent dangerous accidents, the automotive air conditioner controller 1 enters a dry-burn protection mode to take measures to address the fault phenomenon of the PTC electric heater 3. In this mode, the air conditioning system cannot be manually adjusted until the PTC temperature sensor 2 returns to its normal operating temperature range.

Claims

1. A method for controlling dry burning protection of a PTC electric heater for automobile air conditioning, characterized in that: A car air-conditioning PTC electric heater dry-burning protection control system is adopted, wherein the hardware connection includes a car air-conditioning controller (1), an I / O input terminal of the car air-conditioning controller (1) is connected to a PTC electric heater (3), a PTC temperature sensor (2) is arranged on the surface of the PTC electric heater (3), and the car air-conditioning controller (1) is electrically connected to a PTC high-voltage contactor (4), a heating and cooling air door actuator (5), a blower speed control module (6), a mode air door actuator (7), a circulation air door actuator (8), and an instrument panel alarm (9); the PTC temperature sensor (2) adopts an NTC temperature sensor, and is characterized in that the implementation is specifically carried out according to the following steps: Step 1: The PTC temperature sensor (2) collects the temperature value and transmits it to the automobile air conditioning controller (1); Step 2, the automobile air-conditioning controller (1) collects the current temperature value of the PTC temperature sensor (2) and performs dry-burning mode determination processing; Step 3, after entering the dry-burning mode, the automobile air-conditioning controller (1) collects the current temperature value of the PTC temperature sensor (2) to perform dry-burning protection mode judgment processing; The specific process of step 1 is as follows: the automobile air-conditioning heating mode is normally turned on, all circuits of the pure electric vehicle air-conditioning are in a normal state, the PTC temperature sensor (2) collects the temperature value of the surface of the PTC electric heater (3) in real time as the input of the automobile air-conditioning controller (1), and feeds back to the automobile air-conditioning controller (1) in real time; In step 2, the specific process of judging the entry into the dry-burning mode is as follows: preset temperature values A and B are set in the automobile air-conditioning controller (1), A is not greater than B, and the preset value A is set to the maximum temperature allowed by the PTC temperature sensor (2) when the automobile air-conditioning is in a heating condition and the PTC electric heater (3) is working normally; when the current temperature value collected by the PTC temperature sensor (2) is greater than the preset value A, the automobile air-conditioning controller (1) sends a command, the PTC high-voltage contactor (4) stops working, and the dry-burning mode is entered. When the temperature value is no greater than the preset value A, the command stops sending after the execution of the dry-burning mode is completed; In the step 3, the specific process of judging whether to enter the dry-burning protection mode is as follows: when the current temperature value collected by the PTC temperature sensor 2 is greater than the preset value B, the automobile air-conditioning controller (1) is forced to enter the dry-burning protection mode, and the automobile air-conditioning controller (1) sends an instruction to control the cooling and heating air door actuator (5) to run to the full warm position; the blower speed control module (6) controls the blower air volume to be in the maximum wind speed state, the mode air door actuator (7) runs to the maximum defrost mode, and the circulation air door actuator (8) is in the external circulation mode instruction; it is judged again whether the current temperature value collected by the PTC temperature sensor (2) is greater than the preset value B. When it is greater than the preset value B, the instrument panel alarm (9) flashes and displays the PTC fault mark, accompanied by an alarm sound, which is a process end mark; otherwise, the air conditioner returns to the state before the dry-burning protection, and the dry-burning protection mode is not exited at this time until the current temperature value collected is not greater than the preset value B.

2. The dry burning protection control method for a PTC electric heater for an automobile air conditioner according to claim 1, characterized in that: The input quantity of the automobile air-conditioning controller (1) is to collect the current temperature value of the PTC in real time through an NTC temperature sensor arranged on the surface of the pure electric vehicle PTC electric heater (3), and the NTC temperature sensor is connected to the signal input terminal and GND external pins A1 and A2 of the automobile air-conditioning controller (1) through a two-port connector with a length of 310 mm.

3. The dry burning protection control method for a PTC electric heater of an automobile air conditioner according to claim 2, characterized in that: In step 1, the automobile air-conditioning controller (1) converts the collected temperature analog quantity in real time through the RT conversion formula, and calculates the resistance value corresponding to different temperatures, thereby obtaining different currents I generated between the two pins A1 and A2. A1A2 ; R t =R0*exp[C(1 / (T1)-1 / (T0))](1) In formula (1), R t is the resistance of the thermistor to be determined at temperature T1; R0 is the known nominal resistance of the thermistor at temperature T0; C is the thermal sensitivity index of the thermistor, usually 3270; exp is the nth power of the known e; T1 and T0 are K degrees, that is, Kelvin degrees Celsius, K degrees = absolute temperature 273.15 + degrees Celsius, which are known quantities.

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