Air conditioner and fan speed control method thereof

Abstract

The application discloses an air conditioner and a fan rotating speed control method thereof. During operation of the air conditioner, the fan power may be too large, which leads to overloading operation of the fan and increases the risk of damage of the fan. Therefore, in the embodiment of the application, the q-axis current is limited when the fan is controlled, so as to avoid the fan from entering an overloading operation state. In the case of not increasing the cost, avoiding the increase of the size of the whole machine and not affecting the performance of the fan, the risk of damage of the fan is reduced.

Description

Technical Field

[0001] This invention relates to the field of air conditioning technology, and in particular to an air conditioner and a method for controlling the fan speed of the same. Background Technology

[0002] In existing technologies, to prevent air conditioner fans from operating under overload conditions, redundant designs or fan speed limits are typically employed. However, implementing redundant designs for the fans increases costs and affects the overall structural design, potentially leading to a larger overall size. Limiting fan speed restricts the fan's speed even during normal operation, preventing it from performing at its full potential and resulting in a poor user experience. Summary of the Invention

[0003] The purpose of this invention is to provide an air conditioner and its fan speed control method, which can limit the q-axis current by setting a q-axis current threshold, thereby preventing the fan from entering an overload operation state without increasing the cost, avoiding an increase in the overall size of the unit, and without affecting the performance of the fan, thus avoiding a deterioration in the user experience.

[0004] To achieve the above objectives, embodiments of the present invention provide an air conditioner, comprising:

[0005] The refrigerant circuit circulates refrigerant sequentially through a compressor, condenser, expansion valve, and evaporator; one of the condenser and the evaporator is an outdoor heat exchanger, and the other is an indoor heat exchanger.

[0006] A fan is used to exchange heat in a heat exchanger using airflow; wherein the heat exchanger is an indoor heat exchanger or an outdoor heat exchanger.

[0007] The controller is configured as follows:

[0008] Obtain the speed feedback value, q-axis current feedback value, and d-axis current feedback value of the fan;

[0009] The difference between the preset d-axis current command value and the d-axis current feedback value is adjusted by PI to obtain the d-axis voltage command value;

[0010] The difference between the input speed command value and the speed feedback value is adjusted by PI to obtain the q-axis current command value;

[0011] When the q-axis current command value is greater than the preset q-axis current threshold, the difference between the q-axis current threshold and the q-axis current feedback value is adjusted by PI to obtain the q-axis voltage command value.

[0012] A fan control signal is generated based on the q-axis voltage command value and the d-axis voltage command value, and the fan is controlled based on the fan control signal.

[0013] As an improvement to the above solution, after controlling the speed of the fan according to the fan control signal, the phase current of the fan is obtained;

[0014] When a phase current of the wind turbine is detected to be greater than or equal to a preset phase current protection threshold, the q-axis current threshold is reduced.

[0015] When the phase current of the wind turbine is detected to be less than a preset upward adjustment threshold, the q-axis current threshold is increased; wherein the upward adjustment threshold is less than the phase current protection threshold.

[0016] As an improvement to the above solution, the air conditioner further includes:

[0017] An outdoor ambient temperature sensor, installed outdoors, is used to monitor the outdoor ambient temperature.

[0018] An outdoor coil temperature sensor is installed on the outdoor heat exchanger to monitor the outdoor coil temperature.

[0019] The controller is also configured to:

[0020] The DC-side power supply voltage, the outdoor coil temperature, and the outdoor ambient temperature are obtained as current threshold parameters; wherein, the fan is an outdoor fan, and the heat exchanger is an outdoor heat exchanger.

[0021] Based on the preset mapping relationship between the current threshold parameter and the q-axis current threshold, the initial q-axis current threshold is determined according to the current current threshold parameter; wherein, the DC side power supply voltage value and the q-axis current threshold are positively correlated.

[0022] As an improvement to the above solution, the air conditioner further includes:

[0023] An outdoor ambient temperature sensor, installed outdoors, is used to monitor the outdoor ambient temperature.

[0024] The controller is also configured to:

[0025] The outdoor ambient temperature is obtained and used as the current phase current parameter;

[0026] Based on a preset mapping relationship between phase current parameters and phase current protection thresholds, the phase current protection threshold is determined according to the current phase current parameters; wherein, the phase current parameters and the phase current protection threshold are negatively correlated.

[0027] As an improvement to the above solution, the controller is further configured to:

[0028] When the acquired DC-side power supply voltage value is greater than the preset voltage value, the d-axis current command value is set to a fixed value;

[0029] When the DC-side power supply voltage is less than or equal to the preset voltage value, field weakening control is applied to the d-axis current command value.

[0030] When performing field weakening control on the d-axis current command value, if the fan phase current is detected to be greater than or equal to the preset phase current protection threshold, the d-axis current command value is reduced by a preset step size.

[0031] As an improvement to the above solution, the air conditioner further includes:

[0032] An outdoor ambient temperature sensor, installed outdoors, is used to monitor the outdoor ambient temperature.

[0033] An outdoor coil temperature sensor is installed on the outdoor heat exchanger to monitor the outdoor coil temperature.

[0034] The controller is also configured to:

[0035] The DC-side power supply voltage, the outdoor coil temperature, and the outdoor ambient temperature are obtained as current threshold parameters; wherein, the fan is an outdoor fan, and the heat exchanger is an outdoor heat exchanger.

[0036] Based on the preset mapping relationship between current threshold parameters and d-axis current command values, the initial d-axis current command value is determined according to the current current threshold parameters; wherein, the DC side power supply voltage value and the d-axis current command value are positively correlated.

[0037] As an improvement to the above scheme, when the q-axis current command value is less than or equal to a preset q-axis current threshold, the difference between the q-axis current command value and the q-axis current feedback value is adjusted by PI to obtain the q-axis voltage command value.

[0038] As an improvement to the above solution, the air conditioner further includes:

[0039] An outdoor coil temperature sensor is installed on the outdoor heat exchanger to monitor the outdoor coil temperature.

[0040] The controller is also configured to:

[0041] Substitute the current outdoor coil temperature into the preset relationship between outdoor coil temperature and fan speed lower limit to determine the current fan speed lower limit; wherein, the outdoor coil temperature and the fan speed lower limit are positively correlated.

[0042] When the fixed wind speed set by the user is less than the current lower limit of the fan speed, the current lower limit of the fan speed is used as the target speed to generate the speed command value;

[0043] When the fixed wind speed is greater than or equal to the current lower limit of the fan speed, the fixed wind speed is used as the target speed to generate the speed command value.

[0044] As an improvement to the above solution, the air conditioner further includes:

[0045] An outdoor ambient temperature sensor, installed outdoors, is used to monitor the outdoor ambient temperature.

[0046] The controller is also configured to:

[0047] Substituting the target speed and the current outdoor ambient temperature into a preset formula relating fan speed, outdoor ambient temperature, and compressor operating frequency range, the compressor operating frequency range corresponding to the target speed and the current outdoor ambient temperature is determined to limit the compressor frequency.

[0048] To achieve the above objectives, embodiments of the present invention also provide a method for controlling the fan speed of an air conditioner, comprising:

[0049] Obtain the fan speed feedback value, q-axis current feedback value, and d-axis current feedback value;

[0050] The difference between the preset d-axis current command value and the d-axis current feedback value is adjusted by PI to obtain the d-axis voltage command value;

[0051] The difference between the input speed command value and the speed feedback value is adjusted by PI to obtain the q-axis current command value;

[0052] When the q-axis current command value is greater than the preset q-axis current threshold, the difference between the q-axis current threshold and the q-axis current feedback value is adjusted by PI to obtain the q-axis voltage command value.

[0053] A fan control signal is generated based on the q-axis voltage command value and the d-axis voltage command value, and the fan is controlled based on the fan control signal.

[0054] Compared to existing technologies, the air conditioner and its fan speed control method disclosed in this invention address the issue that during operation, the air conditioner may experience excessive fan power, leading to fan overload and increased risk of fan damage. Therefore, this invention specifically limits the q-axis current when controlling the fan to prevent it from entering an overload state. This reduces the risk of fan damage without increasing costs, expanding the overall size of the unit, or affecting fan performance. Attached Figure Description

[0055] Figure 1 This is a schematic diagram of the structure of an air conditioner provided in an embodiment of the present invention;

[0056] Figure 2 This is a schematic diagram of the refrigeration system of the air conditioner provided in an embodiment of the present invention;

[0057] Figure 3 This is a block diagram illustrating the principle of a fan speed control algorithm provided in an embodiment of the present invention;

[0058] Figure 4 This is a first working flowchart of the controller provided in an embodiment of the present invention;

[0059] Figure 5 This is a block diagram illustrating the principle of a fan speed control algorithm provided in an embodiment of the present invention;

[0060] Figure 6 This is a second workflow diagram of the controller provided in an embodiment of the present invention;

[0061] Figure 7 This is a third workflow diagram of the controller provided in an embodiment of the present invention;

[0062] Figure 8 This is the fourth workflow diagram of the controller provided in this embodiment of the invention;

[0063] Figure 9 This is the fifth workflow diagram of the controller provided in this embodiment of the invention;

[0064] Figure 10 This is the sixth workflow diagram of the controller provided in this embodiment of the invention;

[0065] Figure 11 This is a flowchart of the air conditioner fan speed control method provided in an embodiment of the present invention;

[0066] Among them, 100 is the indoor unit; 200 is the outdoor unit; 10 is the compressor; 20 is the condenser; 30 is the expansion valve; and 40 is the evaporator. Detailed Implementation

[0067] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0068] In the description of this application, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0069] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "multiple" means two or more.

[0070] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0071] See Figure 1 The air conditioner described in this embodiment of the invention includes an indoor unit 100 and an outdoor unit 200. The indoor unit 100 is used to regulate the temperature and humidity of the indoor air. The outdoor unit 200 is connected to the indoor unit 100 through a connecting pipe. The outdoor unit 200 is installed outdoors, and the indoor unit 100 is installed indoors.

[0072] The air conditioner is equipped with a refrigerant circuit. Specifically, the refrigerant circuit circulates refrigerant sequentially through the compressor, condenser, expansion valve, and evaporator. One of the condenser and the evaporator is an outdoor heat exchanger, and the other is an indoor heat exchanger.

[0073] The heat exchange principle in the refrigerant circuit is as follows:

[0074] See Figure 2The diagram shows the structure of the refrigeration system of an air conditioner. The refrigeration system includes a compressor 10, a condenser 20, an expansion valve 30, and an evaporator 40, forming a refrigerant circuit. The refrigerant cycle involves a series of processes, including compression, condensation, expansion, and evaporation, supplying refrigerant to conditioned and heat-exchanged air. The compressor 10 compresses the refrigerant gas at high temperature and high pressure and discharges the compressed refrigerant gas. The discharged refrigerant gas flows into the condenser 20, where it condenses the compressed refrigerant into a liquid phase, releasing heat to the surrounding environment through the condensation process. The expansion valve 30 expands the high-temperature, high-pressure liquid refrigerant condensed in the condenser 20 into a low-pressure liquid refrigerant. The evaporator 40 evaporates the refrigerant that expanded in the expansion valve and returns the low-temperature, low-pressure refrigerant gas to the compressor 10. The evaporator 40 achieves the cooling effect by utilizing the latent heat of refrigerant evaporation to exchange heat with the material being cooled.

[0075] Throughout the cycle, the air conditioner regulates the temperature of the indoor space. The outdoor unit 200 of the air conditioner refers to the portion of the refrigeration cycle that includes the compressor 10 and the outdoor heat exchanger. The indoor unit 100 of the air conditioner includes an indoor heat exchanger, and the expansion valve 30 can be provided in either the indoor unit 100 or the outdoor unit 200. The indoor and outdoor heat exchangers function as condensers or evaporators. When the indoor heat exchanger functions as a condenser, the air conditioner is a heater for heating; when the indoor heat exchanger functions as an evaporator, the air conditioner is a cooler for cooling.

[0076] It is worth noting that the air conditioner described in the embodiments of the present invention is not limited to the specific split-type air conditioner mentioned above, but can also be an integrated air conditioner, such as a window air conditioner. The specific type of air conditioner is not limited here.

[0077] The air conditioner also includes a fan for exchanging heat with the heat exchanger using airflow. The fan can be an indoor fan or an outdoor fan, and this is not limited to either. When the fan impeller experiences significant resistance, the driving torque of the fan will increase exponentially, which can easily lead to damage to the electrical control system due to excessive current, or damage to the DC motor due to excessive current entering a magnetic saturation state. Therefore, effective control of the fan is necessary to prevent it from entering an overload operation state.

[0078] The air conditioner further includes a controller. Specifically, in this embodiment of the invention, the controller is configured to:

[0079] Obtain the speed feedback value, q-axis current feedback value, and d-axis current feedback value of the fan;

[0080] The difference between the preset d-axis current command value and the d-axis current feedback value is adjusted by PI to obtain the d-axis voltage command value;

[0081] The difference between the input speed command value and the speed feedback value is adjusted by PI to obtain the q-axis current command value;

[0082] When the q-axis current command value is greater than the preset q-axis current threshold, the difference between the q-axis current threshold and the q-axis current feedback value is adjusted by PI to obtain the q-axis voltage command value.

[0083] A fan control signal is generated based on the q-axis voltage command value and the d-axis voltage command, and the fan is controlled based on the fan control signal.

[0084] For example, see Figure 3 and Figure 4 , Figure 3 This is a block diagram illustrating the principle of a fan speed control algorithm according to an embodiment of the present invention. Figure 4 This is a first operational flowchart of a controller provided in an embodiment of the present invention, wherein the controller is used to execute steps S11 to S16:

[0085] S11. Obtain the fan speed feedback value ωr ＊ q-axis current feedback value iq ＊ d-axis current feedback value id ＊ The speed command value ωr and the d-axis current command value id are then entered, and then the process proceeds to step S12.

[0086] S12, regarding the d-axis current command value id and the d-axis current feedback value id ＊ The difference is used for PI adjustment to obtain the d-axis voltage command value vd, and then proceed to step S13.

[0087] S13, regarding the speed command value ωr and the speed feedback value ωr ＊ The difference is used for PI adjustment to obtain the q-axis current command value iqr, and then proceed to step S14.

[0088] S14. Determine whether the q-axis current command value iqr is greater than the preset q-axis current threshold iqy. If yes, proceed to step S15; otherwise, proceed to step S17.

[0089] S15. The q-axis current threshold iqy and the q-axis current feedback value iq... ＊ The difference is used for PI adjustment to obtain the q-axis voltage command value vq, and then proceed to step S16.

[0090] S16. Generate a fan control signal based on the q-axis voltage command value vq and the d-axis voltage command value vd, and control the fan based on the fan control signal.

[0091] S17. The q-axis current command value iqr and the q-axis current feedback value iq...＊ The difference is used for PI adjustment to obtain the q-axis voltage command value vq, and then the process returns to step S16.

[0092] Specifically, the fan speed command value ωr is subtracted from the fan speed feedback value ωr. ＊ Then, a PI limiting filter is used to generate a q-axis current command value iqr. This iqr value is compared with a preset q-axis current threshold iqy input to a selector, and the smaller value is selected. When the iqr value is greater than the iqy threshold, the iqy threshold is used as the new command value to limit the q-axis current and prevent it from becoming too large. Finally, it is compared with the q-axis current feedback value iq. ＊ The difference is calculated, and then the q-axis voltage command value vq is generated through a PI limiting filter; the d-axis current command value id and the d-axis current feedback value id are then compared. ＊ The difference is calculated, and then the PI control is applied through a PI limiting filter to generate the d-axis voltage command value vd. The q-axis voltage command value vq and the d-axis voltage command value vd are transformed by PARK to obtain vα and vβ. Finally, the KLARK inverse transformation is used to generate 6 drive signals to drive the fan and control the fan speed.

[0093] Further, see Figure 5 , Figure 5 This is a block diagram illustrating the principle of a fan speed control algorithm according to an embodiment of the present invention, with the q-axis current feedback value iq. ＊ d-axis current feedback value id ＊ and speed feedback value ωr ＊ The following method is used to generate the values: detect the phase currents iu and iv of the fan, obtain the iw value according to the formula iu + iv + iw = 0, and calculate the angle θ and speed feedback value ωr by combining the obtained quadrature voltage values ​​vα and vβ. ＊ The KLARK transformation of iu, iv, and iw is performed to generate iα and iβ, and then the PARK transformation is performed to generate the q-axis current feedback value iq in the rotor rotating coordinate system. ＊ and d-axis current feedback value id ＊ .

[0094] Furthermore, the fan is an outdoor fan, and the heat exchanger is an outdoor heat exchanger.

[0095] It is worth noting that the embodiments of the present invention are more applicable to the control of outdoor fans.

[0096] In a preferred embodiment, the controller is further configured to:

[0097] After controlling the speed of the fan according to the fan control signal, the fan phase current is obtained;

[0098] When a phase current of the wind turbine is detected to be greater than or equal to a preset phase current protection threshold, the q-axis current threshold iqy is reduced.

[0099] When the phase current of the wind turbine is detected to be less than a preset upward adjustment threshold, the q-axis current threshold iqy is increased; wherein the upward adjustment threshold is less than the phase current protection threshold.

[0100] For example, see Figure 6 , Figure 6 This is a second flowchart of a controller provided in an embodiment of the present invention, wherein the controller is further configured to execute steps S18 to S21:

[0101] S18. Obtain the phase currents iu, iv, and iw of the wind turbine, and then proceed to step S18.

[0102] S19. Determine whether the phase currents iu, iv, and iw of the wind turbine are greater than or equal to the preset phase current protection threshold. If yes, proceed to step S20; otherwise, proceed to step S21.

[0103] S20, reduce the q-axis current threshold iqy.

[0104] S21. When the fan phase currents iu, iv, and iw are less than the preset upward adjustment threshold, the q-axis current threshold iqy is increased.

[0105] Specifically, while using the q-axis current as the control target, the fan phase currents iu, iv, and iw are also used as control scheme constraints. A phase current protection threshold is preset, and the fan phase currents iu, iv, and iw are monitored. If the monitored data exceeds the phase current protection threshold, the q-axis current threshold iqy is reduced by a preset step size to enhance the control of the q-axis current, prevent the fan from entering an overcurrent operating state, and prevent the phase current from exceeding the allowable range of its drive power semiconductor device IPM module or causing the IPM module temperature to exceed its limit. The motor phase current value is also limited, which not only avoids the risk of damage to the semiconductor module and the magnetic materials of the fan body due to excessive current, but also improves the output capability under low voltage conditions.

[0106] It is worth noting that the specific adjustment step size of the q-axis current threshold iqy can be set according to the actual situation, and is not limited here.

[0107] In a preferred embodiment, the air conditioner further includes:

[0108] An outdoor ambient temperature sensor, installed outdoors, is used to monitor the outdoor ambient temperature.

[0109] An outdoor coil temperature sensor is installed on the outdoor heat exchanger to monitor the outdoor coil temperature.

[0110] The controller is also configured to:

[0111] The DC-side power supply voltage, the outdoor coil temperature, and the outdoor ambient temperature are obtained as current threshold parameters; wherein, the fan is an outdoor fan, and the heat exchanger is an outdoor heat exchanger.

[0112] Based on the preset mapping relationship between the current threshold parameter and the q-axis current threshold iqy, the initial q-axis current threshold iqy is determined according to the current current threshold parameter; wherein, the DC side power supply voltage value and the q-axis current threshold iqy are positively correlated.

[0113] It is worth noting that outdoor ambient temperature sensors and outdoor coil temperature sensors are sensors that can sense temperature and convert it into a usable output signal. According to the measurement method, they can be divided into two main categories: contact and non-contact. According to the sensor material and electronic component characteristics, they can be divided into two categories: resistance temperature detectors (RTDs) and thermocouples. Manufacturers can choose the specific temperature sensor according to the actual application requirements.

[0114] For example, see Figure 7 , Figure 7 This is a third flowchart of a controller provided in an embodiment of the present invention, wherein the controller is further configured to execute steps S22 to S24:

[0115] S22. Obtain the DC-side power supply voltage value Vdc, the outdoor coil temperature, and the outdoor ambient temperature as current current threshold parameters; then proceed to step S23.

[0116] S23. Obtain the mapping relationship between the current threshold parameter and the q-axis current threshold iqy, and then proceed to step S24.

[0117] S24. Based on the mapping relationship between the current threshold parameter and the q-axis current threshold iqy, determine the initial q-axis current threshold iqy according to the current current threshold parameter; wherein, the DC side power supply voltage value Vdc and the q-axis current threshold iqy are positively correlated.

[0118] Specifically, as the DC-side supply voltage Vdc changes, its corresponding q-axis current threshold iqy can change synchronously. The higher the voltage value, the larger the corresponding q-axis current threshold iqy is set, and vice versa. To simplify the algorithm, the above correspondence is digitized, that is, the DC-side supply voltage Vdc is divided into several groups, and the q-axis current threshold iqy corresponding to each group of voltage values ​​is different. In the initial stage of wind turbine control, based on experience, the initial q-axis current threshold iqy is first determined by the current state and the preset mapping relationship, and the q-axis current is controlled. Subsequently, the q-axis current threshold iqy is adaptively adjusted according to the actual application conditions to adapt it to the specific actual operating conditions.

[0119] In a preferred embodiment, the air conditioner further includes:

[0120] An outdoor ambient temperature sensor, installed outdoors, is used to monitor the outdoor ambient temperature.

[0121] The controller is also configured to:

[0122] The outdoor ambient temperature is obtained and used as the current phase current parameter;

[0123] Based on a preset mapping relationship between phase current parameters and phase current protection thresholds, the phase current protection threshold is determined according to the current phase current parameters; wherein, the phase current parameters and the phase current protection threshold are negatively correlated.

[0124] For example, see Figure 8 , Figure 8 This is a fourth flowchart of a controller provided in an embodiment of the present invention, wherein the controller is further configured to execute steps S25 to S27:

[0125] S25. Obtain the outdoor ambient temperature as the current phase current parameter, and then proceed to step S26.

[0126] S26. Obtain the mapping relationship between phase current parameters and phase current protection threshold, and then proceed to step S27.

[0127] S27. Based on the mapping relationship between the phase current parameters and the phase current protection threshold, determine the phase current protection threshold according to the current phase current parameters; wherein, the phase current parameters and the phase current protection threshold are negatively correlated.

[0128] Specifically, the phase current protection threshold is set to protect the hardware and prevent damage from excessive current. Therefore, the specific value of the phase current protection threshold is related to the characteristics of the hardware itself. These characteristics vary under different outdoor ambient temperatures. The mapping relationship between the phase current parameter (outdoor ambient temperature) and the phase current protection threshold can be obtained through testing. For example, the outdoor ambient temperatures can be grouped numerically, with each group corresponding to a predetermined phase current protection threshold. Higher temperatures correspond to lower phase current protection thresholds, and lower temperatures correspond to higher thresholds. Furthermore, to avoid frequent changes in the control quantity, a hysteresis scheme is used in the implementation. This involves appropriately reducing the preset current value without damaging the critical current of the hardware, thus obtaining an upward-adjusted threshold.

[0129] In a preferred embodiment, the controller is further configured to:

[0130] When the acquired DC-side power supply voltage value is greater than the preset voltage value, the d-axis current command value is set to a fixed value;

[0131] When the DC-side power supply voltage is less than or equal to the preset voltage value, field weakening control is applied to the d-axis current command value.

[0132] When performing field weakening control on the d-axis current command value, if the fan phase current is detected to be greater than or equal to the preset phase current protection threshold, the d-axis current command value is reduced by a preset step size.

[0133] For example, see Figure 9 , Figure 9 This is the fifth workflow diagram of the controller provided in the embodiment of the present invention, wherein the controller is further configured to execute steps S28 to S31:

[0134] S28. Obtain the DC side power supply voltage value Vdc, and then proceed to step S29.

[0135] S29. Determine whether the DC-side power supply voltage value Vdc is greater than the preset voltage value. If yes, proceed to step S30; otherwise, proceed to step S31.

[0136] S30. Set the d-axis current command value to a fixed value.

[0137] S31. Perform field weakening control on the d-axis current command value, and when the fan phase current is detected to be greater than or equal to the preset phase current protection threshold, reduce the d-axis current command value by a preset step size.

[0138] Specifically, while using the q-axis current as the control target and the fan phase current as the control scheme constraint, the d-axis current is used as an auxiliary control target. There are two control methods for the d-axis current. The first is to achieve optimal output torque control. In this case, there exists an optimal d-axis current command value id that maximizes the output torque of the q-axis current, which is the optimal choice for normal operation control. To simplify the algorithm, the d-axis current command value id can be set to zero. The second is to achieve field weakening control. When the motor speed cannot be increased due to the limitation of the DC-side supply voltage value Vdc, field weakening control can increase the motor speed while keeping the DC-side supply voltage value Vdc constant. While reducing the q-axis current threshold iqy, the d-axis command value can also be adjusted simultaneously. The d-axis command value is generally negative, and the maximum output torque is obtained at the idy0 position corresponding to its maximum torque control point. Within the range of less than idy0, increasing the d-axis command value can reduce the field weakening effect, thereby improving inverter efficiency and contributing to the overall efficiency improvement. Decreasing the d-axis command value can increase the field weakening effect, thereby increasing the actual operating speed of the motor. At the same time, the adjustment of the d-axis command value is limited by the DC side supply voltage Vdc and the phase current protection threshold. Generally, the larger the DC side supply voltage Vdc, the larger the d-axis command value can be adjusted, i.e., the closer it is to the idy0 value. The smaller the DC side supply voltage Vdc, the smaller the d-axis command value needs to be adjusted, i.e., the larger the absolute value in the case of a negative value. When the d-axis command value is adjusted to a small value, the phase current of the motor cannot exceed the phase current protection threshold.

[0139] Specifically, the adjustment of the d-axis command value is limited by the phase current protection threshold. The d-axis command value is divided into several groups according to its value. The smaller the d-axis command value (i.e., the larger its absolute value), the greater the field weakening depth. However, at the same time, the fan phase current also increases. On the one hand, this may cause motor demagnetization, and on the other hand, it may cause the motor to run unstablely. The specific field weakening depth that can be achieved needs to be measured based on the specific motor and actual load. It is necessary to monitor the fan phase current to adjust the d-axis command value to avoid the above defects.

[0140] In a preferred embodiment, the air conditioner further includes:

[0141] An outdoor ambient temperature sensor, installed outdoors, is used to monitor the outdoor ambient temperature.

[0142] An outdoor coil temperature sensor is installed on the outdoor heat exchanger to monitor the outdoor coil temperature.

[0143] The controller is also configured to:

[0144] The DC-side power supply voltage Vdc, the outdoor coil temperature, and the outdoor ambient temperature are obtained as the current current threshold parameters.

[0145] Based on the preset mapping relationship between the current threshold parameter and the d-axis current command value id, the initial d-axis current command value id is determined according to the current current threshold parameter; wherein, the DC side power supply voltage value Vdc and the d-axis current command value id are positively correlated.

[0146] For example, see Figure 10 , Figure 10 This is a sixth flowchart of a controller provided in an embodiment of the present invention, wherein the controller is further configured to execute steps S32 to S34:

[0147] S32. Obtain the DC-side power supply voltage value Vdc, the outdoor coil temperature, and the outdoor ambient temperature as current current threshold parameters, and then proceed to step S33.

[0148] S33. Obtain the mapping relationship between the current threshold parameter and the d-axis current command value id, and proceed to step S34.

[0149] S34. Based on the mapping relationship between the current threshold parameter and the d-axis current command value id, determine the initial d-axis current command value id according to the current current threshold parameter.

[0150] In a preferred embodiment, the controller is further configured to:

[0151] When the q-axis current command value iqr is less than or equal to the preset q-axis current threshold iqy, the q-axis current command value iqr and the q-axis current feedback value iq are... ＊ The difference is adjusted using a PI controller to obtain the q-axis voltage command value vq.

[0152] Specifically, when the q-axis current command value iqr is less than or equal to the q-axis current threshold iqy, it means that the command value is not sufficient to cause the fan to enter an overload operation state. Therefore, there is no need to limit it, and the fan can be controlled according to actual needs.

[0153] In a preferred embodiment, the controller is further configured to: substitute the current outdoor coil temperature into a preset relationship between the outdoor coil temperature and the lower limit of the fan speed to determine the current lower limit of the fan speed; wherein the outdoor coil temperature and the lower limit of the fan speed are positively correlated; when the fixed wind speed set by the user is less than the current lower limit of the fan speed, the current lower limit of the fan speed is used as the target speed to generate the speed command value; when the fixed wind speed is greater than or equal to the current lower limit of the fan speed, the fixed wind speed is used as the target speed to generate the speed command value.

[0154] For example, it is preset that when the outdoor coil temperature Tc of the air conditioner is greater than the temperature preset value Tcn, the fan speed is greater than the wind speed preset value Son, where n is 1, 2, 3, ..., N, and N is a preset natural number. The larger the value of n, the higher the preset value corresponding to the outdoor coil temperature, and the larger the lower limit value of the fan speed (wind speed preset value). In specific applications, the fan speed needs to be limited according to the outdoor coil temperature.

[0155] In a preferred embodiment, the controller is further configured to:

[0156] Substituting the target speed and the current outdoor ambient temperature into a preset formula relating fan speed, outdoor ambient temperature, and compressor operating frequency range, the compressor operating frequency range corresponding to the target speed and the current outdoor ambient temperature is determined to limit the compressor frequency.

[0157] For example, when the actual speed of the fan is limited, the maximum operating frequency of the compressor needs to be limited to ensure that the air conditioner does not experience overload during operation. Simultaneously, the minimum operating frequency is limited to prevent excessive vibration during low-frequency operation. Preset outdoor maximum compressor operating frequency boundary values ​​are established for different outdoor ambient temperatures and fan speeds. For example, after determining the corresponding compressor operating frequency range based on the actual fan speed, if the obtained compressor operating frequency is greater than the maximum value of the determined compressor operating frequency range, the compressor is controlled to operate at the maximum value of that range. If the obtained compressor operating frequency is less than the minimum value of the determined compressor operating frequency range, the compressor is controlled to operate at the minimum value of that range. If the obtained compressor operating frequency falls within the determined compressor operating frequency range, it is controlled according to existing compressor control methods.

[0158] Compared to existing technologies, the air conditioner disclosed in this invention can limit the q-axis current by setting a q-axis current threshold iqy, preventing the fan from entering an overload operation state without increasing costs, avoiding an increase in the overall size of the unit, and without affecting the fan performance, thus avoiding a deterioration in user experience. By setting the d-axis weak magnetic control, it ensures that the fan can output greater capacity when the power supply is low, improving the user experience. By limiting the fan phase current, it prevents the fan from entering an overcurrent operation state, avoiding the risk of damage to the semiconductor module and the magnetic materials of the fan body due to excessive current, while also improving the output capacity under low voltage conditions.

[0159] See Figure 11 , Figure 11This is a flowchart of a fan speed control method for an air conditioner according to an embodiment of the present invention. The fan speed control method for the air conditioner described in this embodiment is implemented by a controller in the air conditioner, and the fan speed control method includes:

[0160] S1. Obtain the fan speed feedback value, q-axis current feedback value, and d-axis current feedback value;

[0161] S2. Perform PI adjustment on the difference between the preset d-axis current command value and the d-axis current feedback value to obtain the d-axis voltage command value;

[0162] S3. The input speed command value and the speed feedback value ωr ＊ The difference is used for PI adjustment to obtain the q-axis current command value;

[0163] S4. When the q-axis current command value is greater than the preset q-axis current threshold, the difference between the q-axis current threshold and the q-axis current feedback value is adjusted by PI to obtain the q-axis voltage command value vq.

[0164] S5. Generate a fan control signal based on the q-axis voltage command value and the d-axis voltage command, and control the fan based on the fan control signal.

[0165] In a preferred embodiment, the method further includes:

[0166] After controlling the speed of the fan according to the fan control signal, the fan phase current is obtained;

[0167] When a phase current of the wind turbine is detected to be greater than or equal to a preset phase current protection threshold, the q-axis current threshold is reduced.

[0168] When the phase current of the wind turbine is detected to be less than a preset upward adjustment threshold, the q-axis current threshold is increased; wherein the upward adjustment threshold is less than the phase current protection threshold.

[0169] In a preferred embodiment, the method further includes:

[0170] Obtain the DC-side power supply voltage, outdoor coil temperature, and outdoor ambient temperature as current threshold parameters;

[0171] Based on the preset mapping relationship between the current threshold parameter and the q-axis current threshold, the initial q-axis current threshold is determined according to the current current threshold parameter; wherein, the DC side power supply voltage value and the q-axis current threshold are positively correlated.

[0172] In a preferred embodiment, the method further includes:

[0173] Obtain the outdoor ambient temperature as a parameter for the current phase current.

[0174] Based on a preset mapping relationship between phase current parameters and phase current protection thresholds, the phase current protection threshold is determined according to the current phase current parameters; wherein, the phase current parameters and the phase current protection threshold are negatively correlated.

[0175] In a preferred embodiment, the method further includes:

[0176] When the acquired DC-side power supply voltage value is greater than the preset voltage value, the d-axis current command value is set to a fixed value;

[0177] When the DC-side power supply voltage is less than or equal to the preset voltage value, field weakening control is applied to the d-axis current command value.

[0178] When performing field weakening control on the d-axis current command value, if the fan phase current is detected to be greater than or equal to the preset phase current protection threshold, the d-axis current command value is reduced by a preset step size.

[0179] In a preferred embodiment, the method further includes:

[0180] The DC-side power supply voltage, the outdoor coil temperature, and the outdoor ambient temperature are obtained as current threshold parameters; wherein, the fan is an outdoor fan, and the heat exchanger is an outdoor heat exchanger.

[0181] Based on the preset mapping relationship between current threshold parameters and d-axis current command values, the initial d-axis current command value is determined according to the current current threshold parameters; wherein, the DC side power supply voltage value Vdc and the d-axis current command value are positively correlated.

[0182] In a preferred embodiment, the method further includes:

[0183] When the q-axis current command value is less than or equal to the preset q-axis current threshold, the difference between the q-axis current command value and the q-axis current feedback value is adjusted by PI to obtain the q-axis voltage command value.

[0184] In a preferred embodiment, the method further includes:

[0185] Substitute the current outdoor coil temperature into the preset relationship between outdoor coil temperature and fan speed lower limit to determine the current fan speed lower limit; wherein, the outdoor coil temperature and the fan speed lower limit are positively correlated.

[0186] When the fixed wind speed set by the user is less than the current lower limit of the fan speed, the current lower limit of the fan speed is used as the target speed to generate the speed command value;

[0187] When the fixed wind speed is greater than or equal to the current lower limit of the fan speed, the fixed wind speed is used as the target speed to generate the speed command value.

[0188] In a preferred embodiment, the method further includes:

[0189] Substituting the target speed and the current outdoor ambient temperature into a preset formula relating fan speed, outdoor ambient temperature, and compressor operating frequency range, the compressor operating frequency range corresponding to the target speed and the current outdoor ambient temperature is determined to limit the compressor frequency.

[0190] Compared to existing technologies, the air conditioner fan speed control method disclosed in this invention can limit the q-axis current by setting a q-axis current threshold iqy, preventing the fan from entering an overload operation state without increasing costs, avoiding an increase in the overall size of the unit, and without affecting the fan performance, thus avoiding a deterioration in user experience. By setting the d-axis weak magnetic control, it ensures that the fan can output greater capacity when the power supply is low, improving the user experience. By limiting the fan phase current, it prevents the fan from entering an overcurrent operation state, avoiding the risk of damage to the semiconductor module and the magnetic materials of the fan body due to excessive current, while also improving the output capacity under low voltage conditions.

[0191] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. An air conditioner, characterized in that, include: The refrigerant circuit circulates refrigerant sequentially through a compressor, condenser, expansion valve, and evaporator; one of the condenser and the evaporator is an outdoor heat exchanger, and the other is an indoor heat exchanger. A fan is used to exchange heat in a heat exchanger using airflow; wherein the heat exchanger is an indoor heat exchanger or an outdoor heat exchanger. The controller is configured as follows: Obtain the speed feedback value, q-axis current feedback value, and d-axis current feedback value of the fan; The difference between the preset d-axis current command value and the d-axis current feedback value is adjusted by PI to obtain the d-axis voltage command value; The difference between the input speed command value and the speed feedback value is adjusted by PI to obtain the q-axis current command value; When the q-axis current command value is greater than the preset q-axis current threshold, the difference between the q-axis current threshold and the q-axis current feedback value is adjusted by PI to obtain the q-axis voltage command value. A fan control signal is generated based on the q-axis voltage command value and the d-axis voltage command value, and the fan is controlled based on the fan control signal. The controller is also configured to: After controlling the speed of the fan according to the fan control signal, the fan phase current is obtained; When a phase current of the wind turbine is detected to be greater than or equal to a preset phase current protection threshold, the q-axis current threshold is reduced. When the phase current of the wind turbine is detected to be less than a preset upward adjustment threshold, the q-axis current threshold is increased; wherein the upward adjustment threshold is less than the phase current protection threshold. When the q-axis current command value is less than or equal to the preset q-axis current threshold, the difference between the q-axis current command value and the q-axis current feedback value is adjusted by PI to obtain the q-axis voltage command value. The air conditioner also includes: An outdoor ambient temperature sensor, installed outdoors, is used to monitor the outdoor ambient temperature. The controller is also configured to: The outdoor ambient temperature is obtained as the current phase current parameter; wherein, the fan is an outdoor fan, and the heat exchanger is an outdoor heat exchanger; Based on a preset mapping relationship between phase current parameters and phase current protection thresholds, the phase current protection threshold is determined according to the current phase current parameters; wherein, the phase current parameters and the phase current protection threshold are negatively correlated.

2. The air conditioner as described in claim 1, characterized in that, The air conditioner also includes: An outdoor ambient temperature sensor, installed outdoors, is used to monitor the outdoor ambient temperature. An outdoor coil temperature sensor is installed on the outdoor heat exchanger to monitor the outdoor coil temperature. The controller is also configured to: The DC-side power supply voltage, the outdoor coil temperature, and the outdoor ambient temperature are obtained as current threshold parameters; wherein, the fan is an outdoor fan, and the heat exchanger is an outdoor heat exchanger. Based on the preset mapping relationship between the current threshold parameter and the q-axis current threshold, the initial q-axis current threshold is determined according to the current current threshold parameter; wherein, the DC side power supply voltage value and the q-axis current threshold are positively correlated.

3. The air conditioner as described in claim 1, characterized in that, The controller is also configured to: When the acquired DC-side power supply voltage value is greater than the preset voltage value, the d-axis current command value is set to a fixed value; When the DC-side power supply voltage is less than or equal to the preset voltage value, field weakening control is applied to the d-axis current command value. When performing field weakening control on the d-axis current command value, if the fan phase current is detected to be greater than or equal to the preset phase current protection threshold, the d-axis current command value is reduced by a preset step size.

4. The air conditioner as described in claim 1 or 3, characterized in that, The air conditioner also includes: An outdoor ambient temperature sensor, installed outdoors, is used to monitor the outdoor ambient temperature. An outdoor coil temperature sensor is installed on the outdoor heat exchanger to monitor the outdoor coil temperature. The controller is also configured to: The DC-side power supply voltage, the outdoor coil temperature, and the outdoor ambient temperature are obtained as current threshold parameters; wherein, the fan is an outdoor fan, and the heat exchanger is an outdoor heat exchanger. Based on the preset mapping relationship between current threshold parameters and d-axis current command values, the initial d-axis current command value is determined according to the current current threshold parameters; wherein, the DC side power supply voltage value and the d-axis current command value are positively correlated.

5. The air conditioner as described in claim 1, characterized in that, The air conditioner also includes: An outdoor coil temperature sensor is installed on the outdoor heat exchanger to monitor the outdoor coil temperature. The controller is also configured to: Substitute the current outdoor coil temperature into the preset relationship between outdoor coil temperature and fan speed lower limit to determine the current fan speed lower limit; wherein, the outdoor coil temperature and the fan speed lower limit are positively correlated. When the fixed wind speed set by the user is less than the current lower limit of the fan speed, the current lower limit of the fan speed is used as the target speed to generate the speed command value; When the fixed wind speed is greater than or equal to the current lower limit of the fan speed, the fixed wind speed is used as the target speed to generate the speed command value.

6. The air conditioner as described in claim 5, characterized in that, The air conditioner also includes: An outdoor ambient temperature sensor, installed outdoors, is used to monitor the outdoor ambient temperature. The controller is also configured to: Substituting the target speed and the current outdoor ambient temperature into a preset formula relating fan speed, outdoor ambient temperature, and compressor operating frequency range, the compressor operating frequency range corresponding to the target speed and the current outdoor ambient temperature is determined to limit the compressor frequency.

7. A method for controlling the fan speed of an air conditioner, characterized in that, include: Obtain the fan speed feedback value, q-axis current feedback value, and d-axis current feedback value; The difference between the preset d-axis current command value and the d-axis current feedback value is adjusted by PI to obtain the d-axis voltage command value; The difference between the input speed command value and the speed feedback value is adjusted by PI to obtain the q-axis current command value; When the q-axis current command value is greater than the preset q-axis current threshold, the difference between the q-axis current threshold and the q-axis current feedback value is adjusted by PI to obtain the q-axis voltage command value. A fan control signal is generated based on the q-axis voltage command value and the d-axis voltage command value, and the fan is controlled based on the fan control signal. The outdoor ambient temperature is obtained as a parameter for the current phase current; wherein, the fan is an outdoor fan; Based on a preset mapping relationship between phase current parameters and phase current protection thresholds, the phase current protection threshold is determined according to the current phase current parameters; wherein, the phase current parameters and the phase current protection threshold are negatively correlated. After controlling the speed of the fan according to the fan control signal, the fan phase current is obtained; When a phase current of the wind turbine is detected to be greater than or equal to a preset phase current protection threshold, the q-axis current threshold is reduced. When the phase current of the wind turbine is detected to be less than a preset upward adjustment threshold, the q-axis current threshold is increased; wherein the upward adjustment threshold is less than the phase current protection threshold. When the q-axis current command value is less than or equal to the preset q-axis current threshold, the difference between the q-axis current command value and the q-axis current feedback value is adjusted by PI to obtain the q-axis voltage command value.

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