Air conditioner

Abstract

The application discloses an air conditioner, which comprises a refrigerant circulation system, an electric heating body, a first temperature sensor, a second temperature sensor, a stepless power regulating driving circuit and a controller. The refrigerant circulation system is used for making refrigerant perform freezing circulation in a circuit composed of a compressor, a first heat exchanger, a throttling device and a second heat exchanger, so as to realize temperature regulation of a target space; the electric heating body is used for auxiliary heating in a heating mode; the first temperature sensor is used for collecting the temperature of the surface of the electric heating body; the second temperature sensor is used for collecting the ambient temperature; the stepless power regulating driving circuit is connected with the electric heating body and is used for regulating the working power of the electric heating body. By adopting the air conditioner, the working power of the electric heating body can be regulated by the closed-loop control strategy combining the stepless power regulating driving circuit and temperature feedback in the heating mode, the electric heating body is actively and accurately protected, the passive protection of the electric heating body is avoided from being frequently triggered, and the safety and reliability of the air conditioner are improved.

Description

Technical Field

[0001] This invention relates to the field of air conditioning technology, and in particular to an air conditioner. Background Technology

[0002] In existing technologies, electric heating elements are used to improve heating performance in low-temperature environments during air conditioning heating mode. Current air conditioners generally use relay control to operate the electric heating element. This method relies entirely on passive protection devices (thermostat connected in series with a fuse) for over-temperature protection, and cannot actively and accurately adjust the operating power of the electric heating element to protect it. Under specific heating conditions, the electric heating element's prolonged and periodic triggering of passive protection during heating can affect the safety and reliability of the air conditioner. Summary of the Invention

[0003] This invention aims to at least solve one of the technical problems existing in the prior art. Therefore, one objective of this invention is to provide an air conditioner that, in heating mode, can adjust the operating power of the electric heating element through a closed-loop control strategy combining a stepless power adjustment drive circuit and temperature feedback. This proactively and precisely protects the electric heating element, avoiding frequent triggering of passive protection mechanisms, and improving the safety and reliability of the air conditioner.

[0004] To address the aforementioned problems, a first aspect of the present invention provides an air conditioner, comprising: a refrigerant circulation system for circulating refrigerant in a loop consisting of a compressor, a first heat exchanger, a throttling device, and a second heat exchanger to achieve temperature regulation of a target space; an electric heating element for auxiliary heating in heating mode; a first temperature sensor for collecting the surface temperature of the electric heating element; a second temperature sensor for collecting the ambient temperature; a continuously variable power (CVT) drive circuit connected to the electric heating element for adjusting the operating power of the electric heating element; and a controller configured to: operate the refrigerant circulation system in heating mode; obtain a first temperature difference between the ambient temperature and the air conditioner's set temperature; determine a target temperature protection threshold for the electric heating element based on the first temperature difference; obtain a second temperature difference between the surface temperature of the electric heating element and the target temperature protection threshold; determine a control signal duty cycle based on the second temperature difference, and control the conduction time of the power device in the CVT drive circuit based on the control signal duty cycle, so that the surface temperature of the electric heating element is lower than the target temperature protection threshold.

[0005] According to an embodiment of the present invention, the air conditioner regulates the temperature of the target space through a refrigerant circulation system. In heating mode, the temperature sensor collects the surface temperature of the electric heating element and the ambient temperature in real time. Based on the collected temperature, the stepless power adjustment drive circuit adjusts the working power of the electric heating element, forming a closed-loop control strategy that combines the stepless power adjustment drive circuit with temperature feedback to regulate the working power of the electric heating element. This actively and accurately protects the electric heating element, avoids frequent triggering of the electric heating element's passive protection, and improves the safety and reliability of the air conditioner.

[0006] In some embodiments, when determining the target temperature protection threshold, the controller is configured to: determine a target auxiliary heating mode based on the first temperature difference, wherein the target temperature protection threshold is the temperature protection temperature threshold corresponding to the electric heating element set under the target auxiliary heating mode.

[0007] The above technical solution has the following advantages or beneficial effects: by obtaining the first temperature difference between the ambient temperature and the air conditioner set temperature, the target auxiliary heating mode and the target temperature protection threshold are set according to the first temperature difference, so that the heating temperature of the electric heating element is always lower than the target temperature protection threshold, thus avoiding frequent triggering of the electric heating element's passive protection.

[0008] In some embodiments, the controller is configured to: determine the target auxiliary heating mode as a first auxiliary heating mode and the target temperature protection threshold as a first temperature protection threshold when the first temperature difference is less than a first temperature difference threshold; determine the target auxiliary heating mode as a second auxiliary heating mode and the target temperature protection threshold as a second temperature protection threshold when the first temperature difference is greater than a second temperature difference threshold; wherein the first temperature difference threshold is less than or equal to the second temperature difference threshold, and the first temperature protection threshold is less than the second temperature protection threshold.

[0009] The above technical solution has the following advantages or beneficial effects: setting the target auxiliary heating mode as the first auxiliary heating mode or the second auxiliary heating mode, setting the temperature protection threshold according to different auxiliary heating modes, and controlling the working power of the electric heating element more accurately.

[0010] In some embodiments, the air conditioner further includes: a fan for driving airflow; a speed sensor for acquiring the speed of the fan; and the controller is further configured such that, at the same speed of the fan, the larger the duty cycle of the control signal, the greater the output power of the continuously variable power drive circuit and the higher the temperature of the electric heating element.

[0011] The above technical solution has the following advantages or beneficial effects: by adjusting the duty cycle of the control signal, the output power of the stepless power adjustment drive circuit is adjusted, thereby regulating the temperature of the electric heating element.

[0012] In some embodiments, the controller is further configured to: determine that the air conditioner has entered the heating exit mode, and send the control signal with a duty cycle of zero so that the electric heating element stops heating.

[0013] The above technical solution has the following advantages or beneficial effects: when the air conditioner stops heating, the electric heating element stops heating by adjusting the duty cycle of the control signal, thus avoiding continuous heating of the electric heating element and causing malfunction.

[0014] In some embodiments, the air conditioner further includes a fan, and the controller is further configured to control the fan to operate at the maximum permissible air supply level in the heating off mode.

[0015] The above technical solution has the following advantages or beneficial effects: when the air conditioner stops heating, the fan runs at the maximum allowable air supply level to cool the electric heating element as quickly as possible, avoiding overheating of the electric heating element and damage to the device.

[0016] In some embodiments, the controller is further configured to: when the temperature on the surface of the electric heating element is lower than the heating exit temperature threshold, control the fan to stop running and close the air damper of the air conditioner to shut down or exit the heating mode, wherein the heating exit temperature threshold is less than a first temperature protection threshold and the heating exit temperature threshold is less than a second temperature protection threshold.

[0017] The above technical solution has the following advantages or beneficial effects: setting the heating exit temperature threshold to be less than the first temperature protection threshold and the second temperature protection threshold, the air conditioner will shut down or exit the heating mode when the temperature of the electric heating element surface is lower than the heating exit temperature threshold, thus ensuring that the temperature of the electric heating element drops to a safe temperature while saving energy.

[0018] In some embodiments, the air conditioner further includes a passive protection device connected between the electric heating element and the stepless power adjustment drive circuit. The passive protection device is used to perform primary protection when the temperature on the surface of the electric heating element exceeds the primary temperature protection threshold and to perform secondary protection when the temperature on the surface of the electric heating element exceeds the secondary temperature protection threshold. The primary temperature protection threshold is greater than the target temperature protection threshold, and the secondary temperature protection threshold is greater than the primary temperature protection threshold.

[0019] The above technical solution has the following advantages or beneficial effects: By setting a passive protection device between the electric heating element and the stepless power regulation drive circuit, passive protection is provided when the working power of the electric heating element cannot be accurately controlled due to a fault, and the temperature of the electric heating element continues to rise, thus avoiding damage to the air conditioner.

[0020] In some embodiments, the passive protection device includes a temperature controller disposed between the electric heating element and the stepless power adjustment drive circuit, which is used to disconnect to perform the first-level protection when the temperature on the surface of the electric heating element exceeds the first-level temperature protection threshold, and to connect when the temperature on the surface of the electric heating element is lower than the first-level temperature protection threshold.

[0021] The above technical solution has the following advantages or beneficial effects: the passive protection is set to the first-level temperature protection. When the temperature of the surface of the electric heating element exceeds the first-level temperature protection threshold, the thermostat is disconnected. At this time, the temperature of the electric heating element is too high, but it will not damage other devices. Therefore, it is only necessary to disconnect the thermostat. The thermostat can be closed after the temperature of the surface of the electric heating element is lower than the first-level temperature protection threshold.

[0022] In some embodiments, the passive protection device further includes a fuse connected in series with the temperature controller, the fuse being used to disconnect when the temperature on the surface of the electric heating element exceeds the secondary temperature protection threshold for secondary protection.

[0023] The above technical solution has the following advantages or beneficial effects: the passive protection is set to secondary protection. When the temperature on the surface of the electric heating element exceeds the secondary temperature protection threshold, the fuse will trip. At this time, the electric heating element may malfunction, and the high temperature generated may damage other devices. Therefore, the fuse trips to ensure the safety of the air conditioner.

[0024] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0025] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0026] Figure 1 This is a perspective view of an air conditioner according to an embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram of a refrigerant circulation system according to an embodiment of the present invention;

[0028] Figure 3 This is a structural block diagram of an air conditioner according to an embodiment of the present invention;

[0029] Figure 4 This is a control flowchart of a controller according to an embodiment of the present invention;

[0030] Figure 5 This is a structural block diagram of an air conditioner according to an embodiment of the present invention;

[0031] Figure 6This is a schematic diagram of different modes of an air conditioner according to an embodiment of the present invention;

[0032] Figure 7 This is a schematic diagram of a conventional electric heating element over-temperature protection hardware architecture according to an embodiment of the present invention;

[0033] Figure 8 This is a schematic diagram of an over-temperature protection hardware architecture for an electric heating element according to an embodiment of the present invention.

[0034] Figure label:

[0035] Air conditioner 100;

[0036] Outdoor unit 1; connecting pipe 2; indoor unit 3; refrigerant circulation system 110; electric heating element 120; first temperature sensor 130; second temperature sensor 140; stepless power adjustment drive circuit 150; controller 160; fan 170; speed sensor 180; passive protection device 190; compressor 111; first heat exchanger 112; throttling device 113; second heat exchanger 114; thermostat 191; fuse 192. Detailed Implementation

[0037] The embodiments of the present invention are described in detail below. The embodiments described with reference to the accompanying drawings are exemplary. The embodiments of the present invention are described in detail below.

[0038] Air conditioners achieve their cooling and heating cycles through a refrigerant circulation system.

[0039] The refrigerant cycle system includes a compressor, which is usually located in the outdoor unit of the air conditioner. The compressor is a device that transforms low-temperature, low-pressure gaseous refrigerant into high-temperature, high-pressure refrigerant through its operation. It is the "heart" of the air conditioning system and is mainly responsible for compressing and transporting the refrigerant to achieve the function of cooling or heating. In the refrigeration cycle, the compressor draws the refrigerant from the low-pressure area, compresses it, and sends it to the high-pressure area for cooling and condensation. Then, after the pressure is reduced by the throttling device, it enters the evaporator to evaporate and absorb heat, thereby achieving the regulation of parameters such as temperature and humidity in the room or vehicle.

[0040] The refrigerant circulation system also includes a throttling device, which can be a capillary tube or an expansion valve. Taking the expansion valve as an example, the expansion valve throttles the high-temperature, high-pressure liquid refrigerant into low-temperature, low-pressure wet vapor to achieve a cooling effect. The expansion valve is mainly installed between the liquid receiver and the evaporator, and controls the valve flow rate by the heat change at the end of the evaporator, thereby preventing insufficient utilization of the evaporator area and the occurrence of knocking.

[0041] The refrigerant circulation system also includes a switching device, which can be a four-way valve. The four-way valve has four channels or connecting pipes and is a key component in the refrigeration and air conditioning system used to change the direction of refrigerant flow. By changing the direction of refrigerant flow, the four-way valve can switch between the two operating conditions of air conditioning: cooling and heating. The four-way valve is mainly composed of two parts: an electromagnetic pilot valve and a four-way reversing valve. The electromagnetic pilot valve is composed of a valve cup, spring, iron core and electromagnetic coil, while the four-way reversing valve is controlled by the electromagnetic pilot valve. The two are connected by a guide capillary tube.

[0042] The refrigerant circulation system also includes an evaporator, which is specifically designed for the liquid refrigerant to boil and evaporate. The evaporation of the liquid refrigerant absorbs heat from the room, lowering the room temperature, which is the ultimate manifestation of its cooling capacity. During the process of absorbing heat and evaporating to cool the air, the evaporator causes water vapor in the air to condense and separate on the surface of the coils, reducing air humidity and thus having a dehumidifying effect.

[0043] The refrigerant circulation system also includes a condenser passage. As one of the core components of the refrigeration system, the condenser passage efficiently completes the heat exchange task, ensuring the system maintains stable performance during continuous operation. Through its piping design, the condenser passage allows high-temperature, high-pressure refrigerant vapor to enter and exchange heat with the external environment (such as air or water). In the passage, the refrigerant releases a large amount of heat, its temperature gradually decreases, and it eventually changes from a gaseous state to a liquid state. This process achieves effective heat transfer and dissipation, and is a crucial element for the continuous operation of the refrigeration system.

[0044] The outdoor unit of an air conditioner refers to the part of the refrigeration cycle that includes the compressor and the outdoor heat exchanger. The indoor unit of an air conditioner includes the indoor heat exchanger, and the expansion valve can be provided in either the indoor or outdoor unit.

[0045] The indoor and outdoor heat exchangers function as either condensers or evaporators. When the indoor heat exchanger is used as a condenser, the air conditioner functions as a heater in heating mode; when the indoor heat exchanger is used as an evaporator, the air conditioner functions as a cooler in cooling mode.

[0046] like Figure 1 As shown, the air conditioner 100 includes an indoor unit 3 and an outdoor unit 1. The indoor unit 3 is usually installed indoors, and the outdoor unit 1 is usually installed outdoors for heat exchange in the indoor environment. The outdoor unit 1 and the indoor unit 3 are connected by a connecting pipe 2 to perform cooling and heating.

[0047] In existing technologies, electric heating elements are used to improve heating performance in low-temperature environments during air conditioning heating mode. Current air conditioners generally use relay control to operate the electric heating element. This method relies entirely on passive protection devices (thermostat connected in series with a fuse) for over-temperature protection, and cannot actively and accurately adjust the operating power of the electric heating element to protect it. Under specific heating conditions, the electric heating element's prolonged and periodic triggering of passive protection during heating can affect the safety and reliability of the air conditioner.

[0048] To address the aforementioned issues, a first aspect of this invention provides an air conditioner that, in heating mode, adjusts the operating power of the electric heating element through a closed-loop control strategy combining a stepless power adjustment drive circuit and temperature feedback. This proactively and precisely protects the electric heating element, avoiding frequent triggering of passive protection mechanisms and improving the safety and reliability of the air conditioner.

[0049] like Figure 2 As shown, the refrigerant circulation system 110 in the air conditioner 100 includes a compressor 111, a first heat exchanger 112, a throttling device 113, and a second heat exchanger 114.

[0050] The first heat exchanger 112 can be an indoor heat exchanger, and the second heat exchanger 114 can be an outdoor heat exchanger. The refrigerant circulation system 110 is used to make the refrigerant circulate in the loop composed of the compressor 111, the first heat exchanger 112, the throttling device 113 and the second heat exchanger 114 to achieve temperature regulation of the target space.

[0051] like Figure 3 As shown, the air conditioner 100 includes: a refrigerant circulation system 110, an electric heating element 120, a first temperature sensor 130, a second temperature sensor 140, a stepless power adjustment drive circuit 150, and a controller 160.

[0052] The electric heating element 120 is used for auxiliary heating in the heating mode; the first temperature sensor 130 is used to collect the surface temperature of the electric heating element 120; the second temperature sensor 140 is used to collect the ambient temperature; and the stepless power adjustment drive circuit 150 is connected to the electric heating element 120 and is used to adjust the working power of the electric heating element 120.

[0053] Specifically, when the air conditioner 100 is in heating mode, the refrigerant circulation system 110 operates in heating mode to raise the temperature of the target space. Since it takes a certain amount of time for the refrigerant circulation system 110 to raise the temperature of the target space in heating mode, an electric heating element 120 is set up to provide auxiliary heating in heating mode. The electric heating element 120 is a semiconductor ceramic material that uses the positive temperature coefficient to achieve safe, efficient, and temperature-controlled heating. At room temperature, the resistance of the electric heating element 120 is very small. After being powered on, the electric heating element 120 heats up rapidly, and the resistance value increases slowly as the temperature rises.

[0054] To prevent the electric heating element 120 from frequently triggering the automatic protection due to continuous temperature rise, the air conditioner 100 is also equipped with a first temperature sensor 130, a second temperature sensor 140, and a stepless power adjustment drive circuit 150. The first temperature sensor 130 collects the surface temperature of the electric heating element 120, and the second temperature sensor 140 collects the ambient temperature. The target temperature protection threshold of the electric heating element 120 can be determined based on the difference between the ambient temperature and the air conditioner's set temperature. The duty cycle of the control signal is determined based on the difference between the surface temperature of the electric heating element 120 and the target temperature protection threshold. The on-time of the power device in the stepless power adjustment drive circuit 150 is controlled by the duty cycle of the control signal to maintain the temperature of the electric heating element 120 within the target temperature protection threshold.

[0055] Stepless power adjustment refers to the continuous and smooth adjustment of the load output power, thereby enabling output at any power level from 0% to 100%, rather than the traditional fixed levels of high or low gears.

[0056] The stepless power adjustment drive circuit 150 can continuously and smoothly adjust the operating power of the electric heating element 120. The stepless power adjustment drive circuit 150 adjusts the operating power of the electric heating element 120 by changing the duty cycle of the control signal. In the stepless power adjustment drive circuit 150, the MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) is responsible for performing the on and off actions, thereby realizing precise and efficient adjustment of the operating power of the electric heating element 120. For example, the electric heating element 120 can output any power from 0% to 100% through the PWM (Pulse Width Modulation) signal. When the PWM is high, the MOSFET is turned on and the current flows through the electric heating element 120; when the PWM is low, the MOSFET is turned off and the current is interrupted. By changing the duty cycle of the PWM, the on time of the MOSFET changes, thereby changing the operating power of the electric heating element 120.

[0057] Based on the above air conditioner architecture, refer to Figure 4 As shown, the controller of the air conditioner is configured to perform the following steps S1-S5.

[0058] Step S1: The refrigerant circulation system operates in heating mode.

[0059] Specifically, the air conditioner can cool or heat. When cooling or heating, the refrigerant circulation system regulates the temperature of the target space. When the air conditioner is in heating mode, the refrigerant circulation system operates in heating mode to raise the temperature of the target space. Since it takes a certain amount of time for the refrigerant circulation system to raise the temperature of the target space in heating mode, an electric heating element is set up to provide auxiliary heating when the refrigerant circulation system is in heating mode.

[0060] Step S2: Obtain the first temperature difference between the ambient temperature and the air conditioner set temperature.

[0061] Specifically, when the air conditioner is heating, it collects the ambient temperature through a second temperature sensor, compares the current ambient temperature with the temperature set by the air conditioner to obtain a first temperature difference. The first temperature difference can be understood as the temperature increase required for the ambient temperature to reach the set temperature when the air conditioner is heating.

[0062] Step S3: Determine the target temperature protection threshold of the electric heating element based on the first temperature difference.

[0063] Specifically, since the first temperature difference between the ambient temperature and the air conditioner's set temperature is not fixed, the temperature that the electric heating element needs to rise to varies. For example, if the air conditioner is set to 27°C when heating and the current ambient temperature is 10°C, the first temperature difference is 17°C. If the air conditioner is set to 27°C when heating and the current ambient temperature is -10°C, the first temperature difference is 27°C. Therefore, the temperature rise of the electric heating element varies depending on the first temperature difference. It is necessary to determine the target temperature protection threshold of the electric heating element based on the first temperature difference. The target temperature protection threshold can be understood as the highest temperature that the electric heating element can reach. If the temperature of the electric heating element exceeds the target temperature protection threshold, it may damage other components.

[0064] Step S4: Obtain the second temperature difference between the surface temperature of the electric heating element and the target temperature protection threshold.

[0065] Specifically, when the air conditioner is heating, the electric heating element provides auxiliary heating. The temperature of the surface of the electric heating element is collected by the first temperature sensor. The temperature of the surface of the electric heating element is compared with the target temperature protection threshold to obtain the second temperature difference. The second temperature difference can be understood as the difference between the temperature of the surface of the electric heating element and the target temperature protection threshold when the air conditioner is heating.

[0066] Step S5: Determine the duty cycle of the control signal based on the second temperature difference, and control the conduction time of the power device of the stepless power adjustment drive circuit based on the duty cycle of the control signal, so that the temperature of the surface of the electric heating element is lower than the target temperature protection threshold.

[0067] Specifically, upon obtaining the second temperature difference, the duty cycle of the control signal is determined based on this difference. A smaller second temperature difference indicates that the surface temperature of the electric heating element is closer to the target temperature protection threshold; in this case, a smaller control signal duty cycle reduces the operating power of the electric heating element. Conversely, a larger second temperature difference indicates a greater difference between the surface temperature of the electric heating element and the target temperature protection threshold; in this case, a larger control signal duty cycle increases the operating power of the electric heating element. The on-time of the power devices in the continuously variable power (CVT) drive circuit is controlled according to the control signal duty cycle. That is, a smaller control signal duty cycle results in a shorter on-time of the power devices in the CVT, leading to lower operating power of the electric heating element; a larger control signal duty cycle results in a longer on-time of the power devices in the CVT, leading to higher operating power of the electric heating element. The operating power of the electric heating element is adjusted based on the difference between the surface temperature of the electric heating element and the target temperature protection threshold, ensuring that the surface temperature remains below the target temperature protection threshold while the electric heating element is heating.

[0068] According to an embodiment of the present invention, the air conditioner regulates the temperature of the target space through a refrigerant circulation system. In heating mode, the temperature sensor collects the surface temperature of the electric heating element and the ambient temperature in real time. Based on the collected temperature, the stepless power adjustment drive circuit adjusts the working power of the electric heating element, forming a closed-loop control strategy that combines the stepless power adjustment drive circuit with temperature feedback to regulate the working power of the electric heating element. This actively and accurately protects the electric heating element, avoids frequent triggering of the electric heating element's passive protection, and improves the safety and reliability of the air conditioner.

[0069] In some embodiments, the controller is configured to determine a target auxiliary heating mode based on a first temperature difference when determining a target temperature protection threshold, wherein the target temperature protection threshold is the temperature protection threshold corresponding to the electric heating element set under the target auxiliary heating mode.

[0070] Specifically, when the air conditioner is heating, the auxiliary heating of the electric heating element has multiple modes. For example, if the difference between the ambient temperature and the air conditioner's set temperature is small, the target auxiliary heating mode can be the normal heating mode. If the difference between the ambient temperature and the air conditioner's set temperature is large, the target auxiliary heating mode can be the powerful heating mode. The heating intensity of the electric heating element is different in different auxiliary heating modes. Therefore, the temperature protection threshold corresponding to the electric heating element is set according to the target auxiliary heating mode.

[0071] In some embodiments, the controller is configured to: determine the target auxiliary heating mode as the first auxiliary heating mode and the target temperature protection threshold as the first temperature protection threshold when the first temperature difference is less than the first temperature difference threshold; and determine the target auxiliary heating mode as the second auxiliary heating mode and the target temperature protection threshold as the second temperature protection threshold when the first temperature difference is greater than the second temperature difference threshold.

[0072] Wherein, the first temperature difference threshold is less than or equal to the second temperature difference threshold, and the first temperature protection threshold is less than the second temperature protection threshold.

[0073] Specifically, the first temperature difference threshold and the second temperature difference threshold are values ​​set to determine the auxiliary heating mode. For example, the first temperature difference threshold can be 20°C and the second temperature difference threshold can be 30°C, or the first temperature difference threshold can be equal to the second temperature difference threshold of 20°C.

[0074] If the air conditioner is set to 27℃ for heating and the current ambient temperature is 10℃, the first temperature difference is 17℃. This first temperature difference is less than the first temperature difference threshold of 20℃, so the target auxiliary heating mode is the first auxiliary heating mode. Since the difference between the ambient temperature and the air conditioner's set temperature is small, the first auxiliary heating mode is the normal heating mode, and the target temperature protection threshold is the first temperature protection threshold. For example, the first temperature protection threshold could be 70℃. If the air conditioner is set to 27℃ for heating and the current ambient temperature is -10℃, the first temperature difference is 37℃. This first temperature difference is greater than the second temperature difference threshold of 30℃, so the target auxiliary heating mode is the second auxiliary heating mode. Since the difference between the ambient temperature and the air conditioner's set temperature is large, the second auxiliary heating mode is the powerful heating mode, and the target temperature protection threshold is the second temperature protection threshold. For example, the second temperature protection threshold could be 90℃.

[0075] For example, in extremely cold environments, the heating performance of an air conditioner is crucial. To improve heating capacity at low temperatures, air conditioning systems commonly incorporate electric heating technology as an auxiliary means. However, because electric heating elements use 220V power and operate at high temperatures, their safe operation and fault protection become critical issues. Currently, the mainstream solution adopts a passive protection mechanism: a thermostat (recoverable disconnection) and a fuse (non-recoverable fuse) are connected in series in the power supply circuit. This mechanism has significant drawbacks: the thermostat disconnects when the temperature is too high, and if the temperature continues to rise, it triggers the fuse to blow. This passive response method cannot effectively adapt to all air conditioning operating modes, resulting in insufficient protection coverage and potential safety hazards.

[0076] Specifically, in heating mode, when the air conditioner operates at minimum fan speed and minimum air deflector opening, the heat generated by the electric heater cannot be effectively dissipated and accumulates rapidly, causing its temperature to rise quickly. When the temperature reaches the thermostat threshold, the power supply circuit is disconnected (recoverable), the electric heater stops working, and the temperature drops. Once the temperature drops to the recovery threshold, the circuit is reconnected, the electric heater starts working again, and the temperature rises rapidly again. This cycle repeats itself, forming a long-term, periodic passive protection trigger loop, severely affecting the continuity and reliability of system operation. Furthermore, after exiting heating mode, the fan immediately stops and the air deflector closes. The large amount of residual heat in the electric heater body rises rapidly due to lack of heat dissipation (temperature overshoot), easily exceeding the fuse threshold and causing the fuse to blow (irrecoverable), resulting in permanent failure of the electric heating function.

[0077] To overcome the above-mentioned defects, this invention replaces the traditional relay switch scheme with a stepless power regulation closed-loop control strategy based on temperature feedback. By optimizing the control algorithm, the power of the electric heating element is adjusted in real time and accurately, so that its operating temperature is always maintained within the temperature protection threshold range. This not only completely eliminates the risk of melting caused by periodic passive protection triggering and residual heat overshoot, but also significantly improves the operational safety and long-term reliability of the air conditioning system.

[0078] In some embodiments, such as Figure 5 As shown, the air conditioner 100 also includes a fan 170 and a speed sensor 180.

[0079] The fan 170 is used to drive airflow; the speed sensor 180 is used to collect the speed of the fan 170.

[0080] The controller is also configured such that, at the same speed of the fan 170, the larger the duty cycle of the control signal, the greater the output power of the stepless power adjustment drive circuit and the higher the temperature of the electric heating element.

[0081] Specifically, the on-time of the power devices in the stepless power adjustment drive circuit is controlled according to the duty cycle of the control signal. That is, the smaller the duty cycle of the control signal, the shorter the on-time of the power devices in the stepless power adjustment drive circuit, the lower the output power, and the lower the temperature of the electric heating element. At the same speed of the fan 170, the larger the duty cycle of the control signal, the longer the on-time of the power devices in the stepless power adjustment drive circuit, the greater the output power, and the higher the temperature of the electric heating element. The temperature of the electric heating element is adjusted according to the difference between the surface temperature of the electric heating element and the target temperature protection threshold, so that the surface temperature of the electric heating element is lower than the target temperature protection threshold.

[0082] In some embodiments, the controller is further configured to: determine that the air conditioner has entered the heating exit mode, and send a control signal with a duty cycle of zero so that the electric heating element stops heating.

[0083] Specifically, when switching between different modes, the electric heating element needs to stop heating to prevent damage caused by overheating during mode switching. This can be achieved by exiting heating mode and turning off the unit, or entering normal fan mode. When the air conditioner enters the heating-out mode, the electric heating element needs to stop heating. At this time, the control signal duty cycle is zero. The on-time of the power device in the continuously variable power (CVT) drive circuit is controlled according to the control signal duty cycle. That is, the smaller the control signal duty cycle, the shorter the on-time of the power device in the CVT drive circuit, the lower the output power, and the lower the temperature of the electric heating element. When the control signal duty cycle is zero, the power device in the CVT drive circuit does not conduct, and the electric heating element stops heating.

[0084] In some embodiments, the air conditioner also includes a fan, and the controller is further configured to control the fan to operate at the maximum permissible air supply level in heating off mode.

[0085] Specifically, when the heating mode is off, the fan is actively controlled to run at the maximum allowable air supply level to dissipate heat from the electric heating element, effectively suppressing the overshoot of the residual heat temperature of the electric heating element, avoiding damage to components such as fuses, and avoiding passive protection of the air conditioner.

[0086] For example, the greatest advantage of this invention is that it replaces the traditional relay solution with a closed-loop control strategy of stepless power adjustment and temperature feedback, and optimizes the control logic to adjust the heating power of the electric heating element in real time and accurately, thus completely solving the reliability problem caused by the periodic triggering of passive protection under special heating conditions. At the same time, by actively controlling the fan to dissipate heat when exiting the heating mode, it effectively suppresses the overshoot of residual heat temperature and avoids damage to devices such as fuses, thus significantly improving the safety and reliability of the air conditioning system.

[0087] This invention innovatively employs a closed-loop control strategy combining stepless power regulation and temperature feedback, and optimizes the control logic to dynamically adjust the operating power of the electric heating element. This ensures that the temperature of the electric heating element remains stable within the target temperature protection threshold under all operating conditions, achieving proactive and precise temperature protection management. When the air conditioner exits heating mode, the closed-loop control system actively controls the fan to dissipate heat, ensuring that the temperature of the electric heating element remains below the heating exit temperature threshold. This effectively suppresses overshoot of the electric heating element, thus preventing damage to passive protection devices such as fuses. This adaptive overtemperature protection method for air conditioner electric heating elements based on stepless power regulation and temperature feedback can also be applied to other electric heating scenarios, such as electric heating strips.

[0088] In some embodiments, the controller is further configured to: control the fan to stop running and close the air conditioner's damper when the temperature of the surface of the electric heating element is lower than the heating exit temperature threshold, so as to shut down or exit the heating mode.

[0089] Among them, the heating shutdown temperature threshold is less than the first temperature protection threshold, and the heating shutdown temperature threshold is less than the second temperature protection threshold.

[0090] Specifically, when the air conditioner enters the heating exit mode, the electric heating element needs to stop heating. At this time, the duty cycle of the control signal is zero. In the heating exit mode, the fan is actively controlled to run at the maximum allowable air supply level to dissipate heat from the electric heating element. When the surface temperature of the electric heating element is lower than the heating exit temperature threshold, the fan stops running and the air conditioner's damper closes, and the air conditioner shuts off or exits the heating mode. The heating exit temperature threshold can be understood as a value set to determine whether the air conditioner can be shut off or exit the heating mode. When the surface temperature of the electric heating element is lower than the heating exit temperature threshold, the temperature of the electric heating element is low enough that temperature overshoot will not occur and damage devices such as fuses will not occur. For example, the heating exit temperature threshold can be set to 45°C.

[0091] For example, different operating modes of an air conditioner during heating, such as Figure 6 As shown.

[0092] When the air conditioner is turned on / enters heating mode, the controller determines the operating mode of the electric heater. If the heating demand is normal (the difference between the air conditioner's set temperature and the ambient temperature is small, less than the first temperature difference threshold), the electric heater operates in normal mode (first auxiliary heating mode), and the target temperature protection threshold is lower, which is the first temperature protection threshold (e.g., 70℃). If the heating demand is strong (the difference between the air conditioner's set temperature and the ambient temperature is large, greater than the second temperature difference threshold), the electric heater operates in strong mode (second auxiliary heating mode), and the target temperature protection threshold is higher, which is the second temperature protection threshold (e.g., 90℃). When the air conditioner is turned off / exits heating mode, the lowest temperature protection threshold for the electric heater is the heating exit temperature threshold (e.g., 45℃).

[0093] In the whole machine heating mode (normal mode / powerful mode), the controller acquires the fan speed data and electric heating element temperature data in real time, calculates the difference between the current temperature of the electric heating element and the target temperature protection threshold, estimates the required adjustment of the control signal duty cycle based on the current control signal duty cycle, and outputs the control signal.

[0094] The stepless power adjustment drive circuit adjusts the current electric heating element power according to the duty cycle of the control signal to achieve the purpose of controlling the electric heating working temperature (principle: at the same fan speed, the greater the electric heating element power, the higher the electric heating element temperature). The controller continuously adjusts the duty cycle of the control signal to keep the electric heating element temperature stable within the target temperature protection threshold.

[0095] When the unit exits heating mode (shutdown mode), the controller directly outputs a control signal with a duty cycle of 0 to forcibly shut down the heating. To prevent residual heat overshoot, the controller controls the fan to blow air forcefully to dissipate heat from the electric heating element. When the temperature of the electric heating element is lower than the heating exit temperature threshold (45℃), the forceful air blowing stops and the damper closes.

[0096] This invention belongs to the field of air conditioning protection and control technology, specifically relating to an adaptive over-temperature protection method for air conditioning electric heating elements based on stepless power regulation and temperature feedback. This invention breaks through the traditional relay control method, innovatively adopting a closed-loop control strategy combining stepless power regulation and temperature feedback. It can actively and accurately protect and control the electric heating element according to the actual operating conditions in the air conditioning heating mode, effectively avoiding reliability issues caused by the electric heating element's long-term periodic triggering of passive protection under specific operating conditions. Simultaneously, it suppresses the temperature overshoot phenomenon of the electric heating element when the air conditioner exits heating mode, thereby protecting passive protection devices from over-temperature damage. Ultimately, this invention achieves adaptive over-temperature protection for the air conditioning electric heating element, significantly improving the safety and reliability of the air conditioning system.

[0097] In some embodiments, such as Figure 5 As shown, the air conditioner 100 also includes a passive protection device 190.

[0098] The passive protection device 190 is connected between the electric heating element and the stepless power adjustment drive circuit. It is used to perform first-level protection when the temperature of the surface of the electric heating element exceeds the first-level temperature protection threshold and to perform second-level protection when the temperature of the surface of the electric heating element exceeds the second-level temperature protection threshold.

[0099] Among them, the first-level temperature protection threshold is greater than the target temperature protection threshold, and the second-level temperature protection threshold is greater than the first-level temperature protection threshold.

[0100] Specifically, the passive protection device 190 is located between the electric heating element and the stepless power adjustment drive circuit. When the temperature of the electric heating element is too high, passive protection is performed. Although the temperature of the electric heating element is controlled by a closed-loop logic combining stepless power adjustment and temperature feedback in this invention, the passive protection device 190 is required to protect the air conditioner when the stepless power adjustment drive circuit fails and cannot accurately control the electric heating element.

[0101] The primary and secondary temperature protection thresholds can be understood as values ​​set to determine the level of passive protection. For example, the primary temperature protection threshold can be 100℃ and the secondary temperature protection threshold can be 120℃. Within the target temperature protection threshold, the working power of the electric heating element is adjusted by the stepless power adjustment drive circuit. Therefore, the primary temperature protection threshold needs to be greater than the target temperature protection threshold. Passive protection is performed outside the target temperature protection threshold. The passive protection mode is determined according to the temperature of the heating element surface. Primary protection is performed when the temperature of the electric heating element surface exceeds the primary temperature protection threshold, and secondary protection is performed when the temperature of the electric heating element surface exceeds the secondary temperature protection threshold.

[0102] In some embodiments, such as Figure 5 As shown, the passive protection device 190 includes a temperature controller 191.

[0103] The temperature controller 191 is located between the electric heating element and the stepless power adjustment drive circuit. It is used to disconnect when the temperature of the surface of the electric heating element exceeds the first-level temperature protection threshold for first-level protection, and to connect when the temperature of the surface of the electric heating element is lower than the first-level temperature protection threshold.

[0104] Specifically, when the surface temperature of the electric heating element is too high, the electric heating element needs to stop heating. Therefore, when the surface temperature of the electric heating element exceeds the first-level temperature protection threshold, the temperature controller 191 disconnects to perform first-level protection, while continuing to monitor the surface temperature of the electric heating element. When the surface temperature of the electric heating element is lower than the first-level temperature protection threshold, the temperature controller 191 turns on, and the stepless power adjustment drive circuit can continue to adjust the working power of the electric heating element.

[0105] In some embodiments, such as Figure 5 As shown, the passive protection device 190 includes a fuse 192.

[0106] The fuse 192 is connected in series with the temperature controller 191. The fuse 192 is used to disconnect when the temperature of the surface of the electric heating element exceeds the secondary temperature protection threshold for secondary protection.

[0107] Specifically, the fuse 192 and the thermostat 191 are connected in series. If either the thermostat 191 or the fuse 192 is disconnected, the stepless power adjustment drive circuit will be disconnected from the electric heating element, causing the electric heating element to stop heating. When the surface temperature of the electric heating element exceeds the secondary temperature protection threshold, the surface temperature of the electric heating element is too high, and the fuse 192 will quickly disconnect for secondary protection. If the fuse 192 cannot close automatically, the user needs to report the problem and the air conditioner needs to be inspected. After the fault is resolved, the fuse 192 will be closed.

[0108] For example, such as Figure 7As shown, the traditional over-temperature protection hardware architecture for electric heating elements includes a controller, a relay, a passive protection circuit (thermostat in series with a fuse), and the electric heating element. In heating mode, the controller activates the relay to power on the electric heating element. When the operating temperature is abnormal, the thermostat triggers a circuit break (automatically recovering after the temperature drops), and the fuse serves as a secondary protection device with a higher threshold. This protection mechanism is an open-loop mode; the controller cannot obtain the electric heating element's operating status and cannot accurately adapt to the current overall operating mode, leading to abnormal heating and the activation of the protection state during low airflow operation or mode switching.

[0109] like Figure 8 As shown, the hardware architecture for over-temperature protection of the electric heating element in this invention includes a controller, a temperature sensor, a speed sensor, a stepless power adjustment drive circuit, a passive protection circuit (temperature controller in series with a fuse), and the electric heating element. The stepless power adjustment drive circuit adjusts the conduction time of the power devices by controlling different duty cycles of the control signal, achieving continuous adjustment of the electric heating element's power and thus controlling its operating temperature. This circuit also has an active shutdown function (power supply is cut off when the control signal duty cycle = 0). The temperature sensor collects real-time surface temperature data of the electric heating element, and the speed sensor synchronously acquires the fan speed, forming a closed-loop control that keeps the electric heating element's operating temperature within the target temperature protection threshold. Different target temperature protection thresholds are set according to different operating conditions of the entire unit, achieving full-condition adaptive protection of the electric heating element in heating mode, with particularly significant effects during low airflow operation or mode switching.

[0110] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example.

[0111] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. An air conditioner, characterized in that, include: The refrigerant circulation system is used to make the refrigerant circulate in a loop consisting of a compressor, a first heat exchanger, a throttling device, and a second heat exchanger to achieve temperature regulation of the target space. An electric heating element is used for auxiliary heating during heating mode; The first temperature sensor is used to collect the temperature of the surface of the electric heating element; The second temperature sensor is used to collect ambient temperature; A stepless power adjustment drive circuit is connected to the electric heating element and is used to adjust the working power of the electric heating element. The controller is configured to: The refrigerant circulation system operates in heating mode; Obtain the first temperature difference between the ambient temperature and the air conditioner set temperature; The target temperature protection threshold of the electric heating element is determined based on the first temperature difference. A second temperature difference is obtained between the surface temperature of the electric heating element and the target temperature protection threshold. The duty cycle of the control signal is determined based on the second temperature difference, and the conduction time of the power device of the stepless power adjustment drive circuit is controlled based on the duty cycle of the control signal, so that the temperature of the surface of the electric heating element is lower than the target temperature protection threshold.

2. The air conditioner according to claim 1, characterized in that, When determining the target temperature protection threshold, the controller is configured to: determine a target auxiliary heating mode based on the first temperature difference, wherein the target temperature protection threshold is the temperature protection threshold corresponding to the electric heating element set under the target auxiliary heating mode.

3. The air conditioner according to claim 2, characterized in that, The controller is configured to: determine the target auxiliary heating mode as the first auxiliary heating mode when the first temperature difference is less than the first temperature difference threshold, and the target temperature protection threshold as the first temperature protection threshold. When the first temperature difference is greater than the second temperature difference threshold, the target auxiliary heating mode is determined to be the second auxiliary heating mode, and the target temperature protection threshold is the second temperature protection threshold. Wherein, the first temperature difference threshold is less than or equal to the second temperature difference threshold, and the first temperature protection threshold is less than the second temperature protection threshold.

4. The air conditioner according to claim 1, characterized in that, The air conditioner also includes: The fan is used to drive airflow; A speed sensor, used to collect the rotational speed of the fan; The controller is also configured such that, at the same speed of the fan, the larger the duty cycle of the control signal, the greater the output power of the continuously variable power drive circuit and the higher the temperature of the electric heating element.

5. The air conditioner according to any one of claims 1-4, characterized in that, The controller is also configured to: determine that the air conditioner has entered the heating exit mode, and send the control signal with a duty cycle of zero so that the electric heating element stops heating.

6. The air conditioner according to claim 5, characterized in that, The air conditioner also includes a fan, and the controller is further configured to control the fan to operate at the maximum permissible air supply level in the heating off mode.

7. The air conditioner according to claim 6, characterized in that, The controller is further configured to: when the temperature on the surface of the electric heating element is lower than the heating exit temperature threshold, control the fan to stop running and close the air damper of the air conditioner to shut down or exit the heating mode, wherein the heating exit temperature threshold is less than a first temperature protection threshold and the heating exit temperature threshold is less than a second temperature protection threshold.

8. The air conditioner according to any one of claims 1-4, characterized in that, The air conditioner also includes a passive protection device connected between the electric heating element and the stepless power adjustment drive circuit. The passive protection device is used to perform primary protection when the temperature on the surface of the electric heating element exceeds the primary temperature protection threshold and to perform secondary protection when the temperature on the surface of the electric heating element exceeds the secondary temperature protection threshold. The primary temperature protection threshold is greater than the target temperature protection threshold, and the secondary temperature protection threshold is greater than the primary temperature protection threshold.

9. The air conditioner according to claim 8, characterized in that, The passive protection device includes a temperature controller, which is disposed between the electric heating element and the stepless power adjustment drive circuit. The temperature controller is used to disconnect to perform the first-level protection when the temperature on the surface of the electric heating element exceeds the first-level temperature protection threshold, and to connect when the temperature on the surface of the electric heating element is lower than the first-level temperature protection threshold.

10. The air conditioner according to claim 9, characterized in that, The passive protection device also includes a fuse, which is connected in series with the temperature controller. The fuse is used to disconnect when the temperature on the surface of the electric heating element exceeds the secondary temperature protection threshold for secondary protection.

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