A fixed frequency air conditioner and motor control method thereof

Abstract

The present invention discloses a fixed-frequency air conditioner and a motor control method thereof. The air conditioner comprises an indoor unit, an outdoor unit and a controller. The outdoor unit is provided with an outdoor heat exchanger, an outdoor fan, an outdoor motor, a liquid side temperature sensor of the outdoor heat exchanger, a compressor, a flow regulating valve and a four-way valve. The controller is configured to control the outdoor motor to run at a preset speed when the air conditioner is in a heating mode. When it is detected that the temperature of the liquid side temperature sensor of the outdoor heat exchanger reaches below a preset temperature threshold, the current speed of the outdoor motor is corrected according to the target speed of the outdoor motor to obtain a corrected speed, and the outdoor motor is controlled to run at the corrected speed. The present invention uses the preset temperature threshold of the liquid side temperature sensor of the outdoor heat exchanger as a critical point to correct the speed of the outdoor motor, effectively avoiding the risk of overload damage to the outdoor motor caused by frosting of the outdoor unit heat exchanger, and improving the reliability of motor operation.

Description

Technical Field

[0001] The present invention relates to the technical field of air conditioning, and in particular to a fixed-frequency air conditioner and a motor control method thereof. Background Art

[0002] With the development of science and technology and the continuous improvement of people's living standards, people have put forward higher and higher requirements for their living environment. In order to maintain a comfortable ambient temperature, air conditioners have become an indispensable electrical appliance in people's lives. In winter, when the outdoor ambient temperature is low, the air conditioner is running for a long time to heat, and the air conditioner outdoor unit heat exchanger is prone to frost, resulting in a decrease in the heating effect. As the frosting time gradually increases, the frost accumulates more and more, and the frost layer increases the heat transfer resistance, resulting in a decrease in the outdoor air circulation area, an increase in flow resistance, and a decrease in air volume, which in turn leads to a further decrease in the outdoor evaporation temperature. The load of the outdoor motor gradually increases, causing the outdoor motor to be at risk of overload damage.

[0003] The existing fixed-frequency air conditioner defrost control mode controls defrost through the outdoor heat exchanger liquid side temperature sensor, ambient temperature and timer. The defrost action will only be entered when the conditions are met. At this time, the outdoor motor is shut down, but it still cannot solve the risk of high-load operation of the outdoor motor for a period of time before entering the defrost. Summary of the invention

[0004] The present invention provides a fixed-frequency air conditioner and a motor control method thereof, which uses a preset temperature threshold of a liquid-side temperature sensor of an outdoor heat exchanger as a critical point to correct the rotation speed of an outdoor motor, thereby effectively avoiding the risk of overload damage to the outdoor motor caused by frosting of the outdoor heat exchanger and improving the operating reliability of the motor.

[0005] The fixed-frequency air conditioner provided in the first embodiment of the present invention comprises:

[0006] An indoor unit, which is equipped with an indoor heat exchanger and an indoor fan;

[0007] An outdoor unit is provided with an outdoor heat exchanger, an outdoor fan, an outdoor motor, a liquid side temperature sensor of the outdoor heat exchanger, a compressor, a flow regulating valve and a four-way valve, wherein the liquid side temperature sensor of the outdoor heat exchanger is used to detect the temperature of the liquid side of the outdoor heat exchanger, and the compressor, the flow regulating valve, the four-way valve, the outdoor heat exchanger and the indoor heat exchanger are connected by pipelines to form a refrigerant circulation loop;

[0008] The controller is configured to control the outdoor motor to operate at a preset speed when the fixed-frequency air conditioner operates in a heating mode; when it is detected that the temperature of the liquid-side temperature sensor of the outdoor heat exchanger reaches below a preset temperature threshold, correct the current speed of the outdoor motor according to the target speed of the outdoor motor to obtain a corrected speed, and control the outdoor motor to operate at the corrected speed.

[0009] In the fixed-frequency air conditioner provided in the second embodiment of the present invention, the controller is configured as follows:

[0010] When the fixed-frequency air conditioner operates in a heating mode, controlling the outdoor motor to reach a maximum speed within the first time;

[0011] After the outdoor motor runs at the maximum speed for a second time, the outdoor motor is controlled to run at a preset speed.

[0012] In the fixed-frequency air conditioner provided in the third embodiment of the present invention, the controller is configured as follows:

[0013] Calculating a first difference between a target speed and a current speed of the outdoor motor, and determining whether an absolute value of the first difference is not greater than a first threshold;

[0014] If yes, controlling the outdoor motor to run at the target speed;

[0015] If not, the target speed of the outdoor motor is added to a first correction value to obtain a corrected speed, and the outdoor motor is controlled to run at the corrected speed; wherein the first correction value is the product of the first difference and a first correction coefficient.

[0016] In the fixed-frequency air conditioner provided in the fourth embodiment of the present invention, the controller is further configured as follows:

[0017] The current gear position of the outdoor motor is corrected according to the target rotation speed of the outdoor motor and the corrected rotation speed to obtain the corrected gear position.

[0018] In the fixed-frequency air conditioner provided in the fifth embodiment of the present invention, the controller is configured as follows:

[0019] calculating a second difference between the corrected rotational speed and the target rotational speed, and determining whether an absolute value of the second difference is not greater than a second threshold;

[0020] If yes, control the outdoor motor to run at the current gear;

[0021] If not, the current gear of the outdoor motor is added to the second correction value to obtain a corrected gear, and the outdoor motor is controlled to run at the corrected gear; wherein the second correction value is the product of the second difference and the second correction coefficient.

[0022] A fixed-frequency air conditioner motor control method is provided in a sixth embodiment of the present invention. The method is applied to a fixed-frequency air conditioner including an indoor heat exchanger, an indoor fan, an outdoor heat exchanger, an outdoor fan, an outdoor motor, a liquid side temperature sensor of the outdoor heat exchanger, a compressor, a flow regulating valve, and a four-way valve. The fixed-frequency air conditioner motor control method includes:

[0023] When the fixed-frequency air conditioner operates in a heating mode, controlling the outdoor motor to operate at a preset speed;

[0024] When it is detected that the temperature of the liquid side temperature sensor of the outdoor heat exchanger reaches below a preset temperature threshold, the current speed of the outdoor motor is corrected according to the target speed of the outdoor motor to obtain a corrected speed, and the outdoor motor is controlled to operate at the corrected speed.

[0025] In the fixed-frequency air conditioner motor control method provided in the seventh embodiment of the present invention, when the fixed-frequency air conditioner operates in a heating mode, controlling the outdoor motor to operate at a preset speed specifically includes:

[0026] When the fixed-frequency air conditioner operates in a heating mode, controlling the outdoor motor to reach a maximum speed within the first time;

[0027] After the outdoor motor runs at the maximum speed for a second time, the outdoor motor is controlled to run at a preset speed.

[0028] In the fixed-frequency air conditioner motor control method provided in the eighth embodiment of the present invention, the current speed of the outdoor motor is corrected according to the target speed of the outdoor motor to obtain the corrected speed, which specifically includes:

[0029] Calculating a first difference between a target speed and a current speed of the outdoor motor, and determining whether an absolute value of the first difference is not greater than a first threshold;

[0030] If yes, controlling the outdoor motor to run at the target speed;

[0031] If not, the target speed of the outdoor motor is added to a first correction value to obtain a corrected speed, and the outdoor motor is controlled to run at the corrected speed; wherein the first correction value is the product of the first difference and a first correction coefficient.

[0032] In the method for controlling a motor of a fixed-frequency air conditioner provided in the ninth embodiment of the present invention, the method further comprises:

[0033] The current gear position of the outdoor motor is corrected according to the target rotation speed of the outdoor motor and the corrected rotation speed to obtain the corrected gear position.

[0034] In the fixed-frequency air conditioner motor control method provided in the tenth embodiment of the present invention, the current gear position of the outdoor motor is corrected according to the target speed of the outdoor motor and the corrected speed to obtain the corrected gear position, which specifically includes:

[0035] calculating a second difference between the corrected rotational speed and the target rotational speed, and determining whether an absolute value of the second difference is not greater than a second threshold;

[0036] If yes, control the outdoor motor to run at the current gear;

[0037] If not, the current gear of the outdoor motor is added to the second correction value to obtain a corrected gear, and the outdoor motor is controlled to run at the corrected gear; wherein the second correction value is the product of the second difference and the second correction coefficient.

[0038] Compared with the prior art, the fixed-frequency air conditioner and the motor control method thereof provided in the embodiment of the present invention have the following beneficial effects: the fixed-frequency air conditioner includes an indoor unit, an outdoor unit and a controller, the indoor unit is provided with an indoor heat exchanger and an indoor fan; the outdoor unit is provided with an outdoor heat exchanger, an outdoor fan, an outdoor motor, a liquid side temperature sensor of the outdoor heat exchanger, a compressor, a flow regulating valve and a four-way valve, the liquid side temperature sensor of the outdoor heat exchanger is used to detect the temperature of the liquid side of the outdoor heat exchanger, the compressor, the flow regulating valve, the four-way valve, the outdoor heat exchanger and the indoor heat exchanger are connected through pipelines to form a refrigerant circulation loop; the controller is configured to control the outdoor motor to run at a preset speed when the fixed-frequency air conditioner is running in a heating mode; when it is detected that the temperature of the liquid side temperature sensor of the outdoor heat exchanger reaches below a preset temperature threshold, the current speed of the outdoor motor is corrected according to the target speed of the outdoor motor to obtain the corrected speed, and the outdoor motor is controlled to run at the corrected speed. The embodiment of the present invention uses the preset temperature threshold of the liquid side temperature sensor of the outdoor heat exchanger as the critical point to correct the rotation speed of the outdoor motor, effectively avoiding the risk of overload damage to the outdoor motor caused by frosting of the outdoor heat exchanger and improving the reliability of motor operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a three-dimensional diagram of the appearance of a fixed-frequency air conditioner provided by one embodiment of the present invention;

[0040] Figure 2 It is a structural schematic diagram of a fixed-frequency air conditioner provided by an embodiment of the present invention;

[0041] Figure 3 It is a schematic diagram of a refrigerant circulation circuit of a fixed-frequency air conditioner provided by one embodiment of the present invention;

[0042] Figure 4 This is a schematic diagram of motor speed signal sampling in a fixed-frequency air conditioner provided by an embodiment of the present invention;

[0043] Figure 5 This is a schematic diagram of the change in motor speed during operation of a fixed-frequency air conditioner provided by an embodiment of the present invention;

[0044] Figure 6 This is a first working flow diagram of a controller in a fixed-frequency air conditioner provided by one embodiment of the present invention;

[0045] Figure 7 is a second working flow diagram of a controller in a fixed-frequency air conditioner provided by an embodiment of the present invention;

[0046] Figure 8 is a third working flow diagram of a controller in a fixed-frequency air conditioner provided by an embodiment of the present invention;

[0047] Fig. 9 is a fourth working flow diagram of a controller in a fixed-frequency air conditioner provided by an embodiment of the present invention;

[0048] Fig.10 The present invention is a flowchart of a method for controlling a motor of a fixed-frequency air conditioner provided in accordance with an embodiment of the present invention. DETAILED DESCRIPTION

[0049] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] In the description of the present application, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0051] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0052] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0053] See also Figure 1 to Figure 2 , Figure 1 is a three-dimensional diagram of the appearance of a fixed-frequency air conditioner provided by one embodiment of the present invention. Figure 2 1 is a structural diagram of a fixed-frequency air conditioner provided in an embodiment of the present invention. The fixed-frequency air conditioner 1 provided in an embodiment of the present invention comprises:

[0054] The indoor unit 2 is provided with an indoor heat exchanger 21 and an indoor fan 22;

[0055] The outdoor unit 3 is provided with an outdoor heat exchanger 31, an outdoor fan 32, an outdoor motor 33, a liquid side temperature sensor 34 of the outdoor heat exchanger, a compressor 35, a flow regulating valve 36 and a four-way valve 37. The liquid side temperature sensor 34 of the outdoor heat exchanger is used to detect the temperature of the liquid side of the outdoor heat exchanger 31. The compressor 35, the flow regulating valve 36, the four-way valve 37, the outdoor heat exchanger 31 and the indoor heat exchanger 21 are connected by pipelines to form a refrigerant circulation loop.

[0056] The controller is configured to control the outdoor motor 33 to run at a preset speed when the fixed-frequency air conditioner 1 runs in a heating mode; when it is detected that the temperature of the outdoor heat exchanger liquid side temperature sensor 34 reaches below a preset temperature threshold, the current speed of the outdoor motor 33 is corrected according to the target speed of the outdoor motor 33 to obtain a corrected speed, and the outdoor motor 33 is controlled to run at the corrected speed.

[0057] Specifically, the fixed frequency air conditioner 1 in the embodiment of the present invention includes an indoor unit 2. Taking the indoor wall mounted unit (shown in the figure) as an example, the indoor wall mounted unit is usually installed on the indoor wall surface. For another example, the indoor cabinet unit (not shown in the figure) is also a form of indoor unit. The outdoor unit 3 is usually installed outdoors and used for indoor environment heat exchange. In addition, Figure 1 In the figure, since the outdoor unit 3 is located outdoors on the opposite side of the indoor unit 2 across the wall, the outdoor unit 3 is indicated by a dotted line. The indoor unit 2 and the outdoor unit 3 are connected by a connecting pipe 4. Among them, the indoor unit 2 is provided with an indoor heat exchanger 21 and an indoor fan 22. The indoor heat exchanger 21 is composed of a plurality of fins and a coil penetrating the plurality of fins. The indoor heat exchanger 21 functions as an evaporator or a radiator according to the operating state of the indoor unit 2, so that heat is exchanged between the refrigerant flowing in the coil and the air passing through the indoor heat exchanger 21. The indoor fan 22 is located in the approximate central part of the indoor unit casing. The indoor fan 22 is a cross-flow fan that is elongated in the longitudinal direction (left-right direction) of the indoor unit 2. By rotating the indoor fan 22, the indoor air is sucked in from the suction port, passes through the air filter, and then passes through the indoor heat exchanger 21. The conditioned air generated is blown out from the blow-out port to the room. The greater the rotation speed of the indoor fan 22, the greater the air volume of the conditioned air blown out from the blow-out port. When the air conditioner is in cooling mode, the indoor heat exchanger 21 works as an evaporator. The indoor heat exchanger 21 functions as an evaporator or a radiator according to the operating state of the indoor unit, so that the refrigerant flowing in the heat transfer tube exchanges heat with the air passing through the indoor heat exchanger. The indoor fan 22 generates an airflow of indoor air passing through the indoor heat exchanger 21 to promote the heat exchange between the refrigerant flowing in the heat transfer tube of the indoor heat exchanger 21 and the indoor air. The outdoor unit 3 is provided with an outdoor heat exchanger 31, an outdoor fan 32, an outdoor motor 33, an outdoor heat exchanger liquid side temperature sensor 34, a compressor 35, a flow regulating valve 36 and a four-way valve 37. The outdoor fan 32 generates an airflow of outdoor air passing through the outdoor heat exchanger 31 to promote the heat exchange between the refrigerant flowing in the heat transfer tube and the outdoor air, and the outdoor fan 32 is driven by an outdoor motor 33 whose rotation speed can be changed. When the air conditioner is in cooling mode, the outdoor heat exchanger 31 works as a condenser. The outdoor fan 32 generates an airflow of outdoor air through the outdoor heat exchanger 31 to promote heat exchange between the refrigerant flowing in the heat transfer tube of the outdoor heat exchanger 31 and the outdoor air. The outdoor heat exchanger liquid side temperature sensor 34 is used to detect the temperature of the outdoor heat exchanger liquid side.

[0058] See also Figure 3 , Figure 3Schematic diagram of a refrigerant circulation circuit of a fixed-frequency air conditioner provided by an embodiment of the present invention. The compressor 35, the flow regulating valve 36, the four-way valve 37, the outdoor heat exchanger 31 and the indoor heat exchanger 21 are connected by pipelines to form a refrigerant circulation circuit. The indoor heat exchanger 21 and the outdoor heat exchanger 31 are used as condensers or evaporators. When the indoor heat exchanger 21 is used as a condenser and the outdoor heat exchanger 31 is used as an evaporator, the air conditioner is used as a heater in the heating mode; when the indoor heat exchanger 21 is used as an evaporator and the outdoor heat exchanger 31 is used as a condenser, the air conditioner is used as a cooler in the cooling mode. The four-way valve 37 is used to control the flow direction of the refrigerant in the refrigerant circulation circuit so that the outdoor heat exchanger and the indoor heat exchanger are switched between being a condenser and an evaporator. When the air conditioner is in the cooling mode, the indoor heat exchanger 21 and the outdoor heat exchanger 31 are used as an evaporator and a condenser, respectively. The refrigerant is compressed by the compressor and converted into a high-temperature and high-pressure gas. It enters the outdoor heat exchanger of the outdoor unit through the four-way valve. After absorbing cold and releasing heat in the outdoor heat exchanger, it becomes a medium-temperature and high-pressure liquid. After passing through the flow control valve, it becomes a low-temperature and low-pressure liquid. After absorbing heat and releasing cold in the indoor heat exchanger of the indoor unit, it becomes a low-temperature and low-pressure gas. It returns to the compressor through the four-way valve and continues to circulate. By circulating the refrigerant in the refrigerant circuit, a vapor compression refrigeration cycle can be performed. Among them, the flow control valve can change the opening degree. By reducing the opening degree, the flow path resistance of the refrigerant passing through the flow control valve is increased; by increasing the opening degree, the flow path resistance of the refrigerant passing through the flow control valve is reduced. Such a flow control valve expands and decompresses the refrigerant flowing from the indoor heat exchanger to the outdoor heat exchanger during refrigeration operation. In addition, even if the state of other components installed in the refrigerant circuit does not change, when the opening degree of the flow control valve changes, the flow rate of the refrigerant flowing in the refrigerant circuit will also change.

[0059] Please note that Figure 4 , Figure 4 This is a schematic diagram of motor speed signal sampling in a fixed-frequency air conditioner provided by an embodiment of the present invention. During the operation of the motor, the speed is read in every 10 seconds, Vi (speed output) sampling is performed every 20 seconds, the voltage signal is converted into a speed signal, and the speed is corrected. This is equivalent to the speed output of the next 10 seconds after the previous speed sampling is corrected.

[0060] When the fixed-frequency air conditioner is operating in the heating mode, the embodiment of the present invention controls the outdoor motor to stably operate at a preset speed; with the preset temperature threshold of the outdoor heat exchanger liquid side temperature sensor as the critical point, when it is detected that the temperature of the outdoor heat exchanger liquid side temperature sensor reaches below the preset temperature threshold, the current speed of the outdoor motor is corrected according to the target speed of the outdoor motor to obtain the corrected speed, and the outdoor motor is controlled to operate at the corrected speed, thereby effectively avoiding the risk of overload damage to the outdoor motor due to frosting of the outdoor unit heat exchanger and improving the reliability of the motor operation.

[0061] As one of the optional embodiments, the controller is configured as:

[0062] When the fixed-frequency air conditioner operates in a heating mode, controlling the outdoor motor to reach a maximum speed within the first time;

[0063] After the outdoor motor runs at the maximum speed for a second time, the outdoor motor is controlled to run at a preset speed.

[0064] For details, please refer to Figure 5 , Figure 5 It is a schematic diagram of the change of motor speed during the operation of a fixed-frequency air conditioner provided by an embodiment of the present invention. In the embodiment of the present invention, when the fixed-frequency air conditioner is running in heating mode, the outdoor motor is first controlled to reach the maximum speed within the first time. After the outdoor motor runs at the maximum speed for the second time, the outdoor motor is controlled to run stably at a preset speed. For example, when the fixed-frequency air conditioner is running in heating mode, the outdoor motor is first controlled to reach the maximum speed within 5 seconds. After the outdoor motor runs at the maximum speed for 1 minute, the speed of the outdoor motor is controlled to be reduced to 80%, and it runs stably at 80%. It should be noted that in this embodiment, the speed is set to reach the target value within 3 seconds without control, because it generally takes 3 seconds for the speed to change from the beginning to stabilize.

[0065] As one of the optional embodiments, the controller is configured as:

[0066] Calculating a first difference between a target speed and a current speed of the outdoor motor, and determining whether an absolute value of the first difference is not greater than a first threshold;

[0067] If yes, controlling the outdoor motor to run at the target speed;

[0068] If not, the target speed of the outdoor motor is added to a first correction value to obtain a corrected speed, and the outdoor motor is controlled to run at the corrected speed; wherein the first correction value is the product of the first difference and a first correction coefficient.

[0069] For details, please refer to Figure 6 and Figure 7 , Figure 6 is a first working flow diagram of a controller in a fixed-frequency air conditioner provided by an embodiment of the present invention. Figure 7 It is a second working flow chart of a controller in a fixed-frequency air conditioner provided by an embodiment of the present invention. The embodiment of the present invention obtains the target speed of the outdoor motor, and corrects the current speed of the outdoor motor according to the target speed of the outdoor motor to obtain the corrected speed. When correcting the speed, the embodiment of the present invention first calculates the first difference between the target speed and the current speed of the outdoor motor, and determines whether the absolute value of the first difference is not greater than the first threshold. If the absolute value of the first difference is not greater than the first threshold, the target speed of the outdoor motor is used as the corrected speed. If the absolute value of the first difference is greater than the first threshold, the target speed of the outdoor motor is added to the first correction value to obtain the corrected speed; wherein the first correction value is the product of the first difference and the first correction coefficient. For example, the first difference between the target speed and the current speed of the outdoor motor is calculated to be ⊿R1, and it is determined whether |⊿R1| is not greater than the first threshold 6. If |⊿R1|≤6, the target speed of the outdoor motor is used as the corrected speed. If |⊿R1|>6, the corrected rotational speed=target rotational speed+⊿R1×first correction coefficient, wherein ⊿R1×first correction coefficient is the first correction amount, and the first correction coefficient is preferably 0.95.

[0070] As one of the optional embodiments, the controller is further configured to:

[0071] The current gear position of the outdoor motor is corrected according to the target rotation speed of the outdoor motor and the corrected rotation speed to obtain the corrected gear position.

[0072] Specifically, after correcting the speed of the outdoor motor, the embodiment of the present invention also corrects the gear of the outdoor motor. The current gear of the outdoor motor is corrected according to the target speed of the outdoor motor and the corrected speed to obtain the corrected gear. The embodiment of the present invention uses the preset temperature threshold of the liquid side temperature sensor of the outdoor heat exchanger as the critical point to correct the speed and gear of the outdoor motor, effectively avoiding the risk of overload damage to the outdoor motor caused by frosting of the outdoor heat exchanger, and improving the reliability of motor operation.

[0073] As one of the optional embodiments, the controller is configured as:

[0074] calculating a second difference between the corrected rotational speed and the target rotational speed, and determining whether an absolute value of the second difference is not greater than a second threshold;

[0075] If yes, control the outdoor motor to run at the current gear;

[0076] If not, the current gear of the outdoor motor is added to the second correction value to obtain a corrected gear, and the outdoor motor is controlled to run at the corrected gear; wherein the second correction value is the product of the second difference and the second correction coefficient.

[0077] For details, please refer to Figure 8 , Figure 8 It is a third working flow chart of a controller in a fixed-frequency air conditioner provided by an embodiment of the present invention. When the gear position is corrected, the embodiment of the present invention first calculates the second difference between the corrected speed and the target speed, and determines whether the absolute value of the second difference is not greater than the second threshold. If the absolute value of the second difference is not greater than the second threshold, the current gear position of the outdoor motor is used as the corrected gear position. If the absolute value of the second difference is greater than the second threshold, the current gear position of the outdoor motor is added to the second correction value to obtain the corrected gear position; wherein the second correction value is the product of the second difference and the second correction coefficient. For example, the second difference between the corrected speed and the target speed is calculated to be ⊿R2, and it is determined whether |⊿R2| is not greater than the second threshold value of 20. If |⊿R2|≤20, the current gear position of the outdoor motor is used as the corrected gear position. If |⊿R2|>20, the corrected gear position = current gear position + ⊿R2×second correction coefficient, wherein ⊿R2×second correction coefficient is the second correction amount. It should be noted that, in this embodiment, when the gear position is corrected, the gear position of the outdoor motor is usually lowered.

[0078] Combine the following Fig. 9 The working process of the fixed-frequency air conditioner provided in this embodiment is described. Fig. 9 This is a fourth working flow diagram of a controller in a fixed-frequency air conditioner provided in one embodiment of the present invention.

[0079] The embodiment of the present invention obtains the target speed of the outdoor motor, firstly calculates the first difference between the target speed and the current speed of the outdoor motor, and determines whether the absolute value of the first difference is not greater than the first threshold value. If the absolute value of the first difference is not greater than the first threshold value, the target speed of the outdoor motor is used as the corrected speed. If the absolute value of the first difference is greater than the first threshold value, the target speed of the outdoor motor is added to the first correction amount to obtain the corrected speed; wherein the first correction amount is the product of the first difference and the first correction coefficient. Then the second difference between the corrected speed and the target speed is calculated, and it is determined whether the absolute value of the second difference is not greater than the second threshold value. If the absolute value of the second difference is not greater than the second threshold value, the current gear of the outdoor motor is used as the corrected gear. If the absolute value of the second difference is greater than the second threshold value, the current gear of the outdoor motor is added to the second correction amount to obtain the corrected gear; wherein the second correction amount is the product of the second difference and the second correction coefficient.

[0080] See also Fig.10 , Fig.10 It is a flow chart of a fixed-frequency air conditioner motor control method provided in one embodiment of the present invention. The fixed-frequency air conditioner motor control method provided in the embodiment of the present invention is applied to a fixed-frequency air conditioner including an indoor heat exchanger, an indoor fan, an outdoor heat exchanger, an outdoor fan, an outdoor motor, an outdoor heat exchanger liquid side temperature sensor, a compressor, a flow regulating valve and a four-way valve, wherein the outdoor heat exchanger liquid side temperature sensor is used to detect the temperature of the outdoor heat exchanger liquid side, and the compressor, the flow regulating valve, the four-way valve, the outdoor heat exchanger and the indoor heat exchanger are connected by pipelines to form a refrigerant circulation loop; the fixed-frequency air conditioner motor control method includes:

[0081] S1. When the fixed-frequency air conditioner operates in a heating mode, controlling the outdoor motor to operate at a preset speed;

[0082] S2. When it is detected that the temperature of the liquid side temperature sensor of the outdoor heat exchanger reaches below a preset temperature threshold, the current speed of the outdoor motor is corrected according to the target speed of the outdoor motor to obtain a corrected speed, and the outdoor motor is controlled to operate at the corrected speed.

[0083] When the fixed-frequency air conditioner is operating in the heating mode, the embodiment of the present invention controls the outdoor motor to stably operate at a preset speed; with the preset temperature threshold of the outdoor heat exchanger liquid side temperature sensor as the critical point, when it is detected that the temperature of the outdoor heat exchanger liquid side temperature sensor reaches below the preset temperature threshold, the current speed of the outdoor motor is corrected according to the target speed of the outdoor motor to obtain the corrected speed, and the outdoor motor is controlled to operate at the corrected speed, thereby effectively avoiding the risk of overload damage to the outdoor motor due to frosting of the outdoor unit heat exchanger and improving the reliability of the motor operation.

[0084] As one of the optional embodiments, when the fixed-frequency air conditioner operates in a heating mode, controlling the outdoor motor to operate at a preset speed specifically includes:

[0085] When the fixed-frequency air conditioner operates in a heating mode, controlling the outdoor motor to reach a maximum speed within the first time;

[0086] After the outdoor motor runs at the maximum speed for a second time, the outdoor motor is controlled to run at a preset speed.

[0087] Specifically, in the embodiment of the present invention, when the fixed-frequency air conditioner is running in the heating mode, the outdoor motor is first controlled to reach the maximum speed within the first time. After the outdoor motor runs at the maximum speed for the second time, the outdoor motor is controlled to run stably at a preset speed. For example, when the fixed-frequency air conditioner is running in the heating mode, the outdoor motor is first controlled to reach the maximum speed within 5 seconds. After the outdoor motor runs at the maximum speed for 1 minute, the speed of the outdoor motor is controlled to be reduced to 80%, and it runs stably at 80%. It should be noted that in this embodiment, the speed is set to reach the target value within 3 seconds without control, because it generally takes 3 seconds for the speed to change from the beginning to stabilize.

[0088] As one of the optional embodiments, the current speed of the outdoor motor is corrected according to the target speed of the outdoor motor to obtain the corrected speed, which specifically includes:

[0089] Calculating a first difference between a target speed and a current speed of the outdoor motor, and determining whether an absolute value of the first difference is not greater than a first threshold;

[0090] If yes, controlling the outdoor motor to run at the target speed;

[0091] If not, the target speed of the outdoor motor is added to a first correction value to obtain a corrected speed, and the outdoor motor is controlled to run at the corrected speed; wherein the first correction value is the product of the first difference and a first correction coefficient.

[0092] Specifically, when the speed is corrected, the embodiment of the present invention first calculates the first difference between the target speed of the outdoor motor and the current speed, and determines whether the absolute value of the first difference is not greater than the first threshold. If the absolute value of the first difference is not greater than the first threshold, the target speed of the outdoor motor is used as the corrected speed. If the absolute value of the first difference is greater than the first threshold, the target speed of the outdoor motor is added to the first correction amount to obtain the corrected speed; wherein the first correction amount is the product of the first difference and the first correction coefficient. For example, the first difference between the target speed of the outdoor motor and the current speed is calculated as ⊿R1, and it is determined whether |⊿R1| is not greater than the first threshold 6. If |⊿R1|≤6, the target speed of the outdoor motor is used as the corrected speed. If |⊿R1|>6, the corrected speed = target speed + ⊿R1×first correction coefficient, wherein ⊿R1×first correction coefficient is the first correction amount, and the first correction coefficient is preferably 0.95.

[0093] As an optional embodiment, the method further includes:

[0094] The current gear position of the outdoor motor is corrected according to the target rotation speed of the outdoor motor and the corrected rotation speed to obtain the corrected gear position.

[0095] Specifically, after correcting the speed of the outdoor motor, the embodiment of the present invention also corrects the gear of the outdoor motor. The current gear of the outdoor motor is corrected according to the target speed of the outdoor motor and the corrected speed to obtain the corrected gear. The embodiment of the present invention uses the preset temperature threshold of the liquid side temperature sensor of the outdoor heat exchanger as the critical point to correct the speed and gear of the outdoor motor, effectively avoiding the risk of overload damage to the outdoor motor caused by frosting of the outdoor heat exchanger, and improving the reliability of motor operation.

[0096] As one of the optional embodiments, the current gear position of the outdoor motor is corrected according to the target speed of the outdoor motor and the corrected speed to obtain the corrected gear position, which specifically includes:

[0097] calculating a second difference between the corrected rotational speed and the target rotational speed, and determining whether an absolute value of the second difference is not greater than a second threshold;

[0098] If yes, control the outdoor motor to run at the current gear;

[0099] If not, the current gear of the outdoor motor is added to the second correction value to obtain a corrected gear, and the outdoor motor is controlled to run at the corrected gear; wherein the second correction value is the product of the second difference and the second correction coefficient.

[0100] Specifically, when the gear position is corrected in the embodiment of the present invention, the second difference between the corrected speed and the target speed is first calculated, and it is determined whether the absolute value of the second difference is not greater than the second threshold. If the absolute value of the second difference is not greater than the second threshold, the current gear position of the outdoor motor is used as the corrected gear position. If the absolute value of the second difference is greater than the second threshold, the current gear position of the outdoor motor is added to the second correction amount to obtain the corrected gear position; wherein the second correction amount is the product of the second difference and the second correction coefficient. For example, the second difference between the corrected speed and the target speed is calculated as ⊿R2, and it is determined whether |⊿R2| is not greater than the second threshold value of 20. If |⊿R2|≤20, the current gear position of the outdoor motor is used as the corrected gear position. If |⊿R2|>20, the corrected gear position = current gear position + ⊿R2×second correction coefficient, wherein ⊿R2×second correction coefficient is the second correction amount. It should be noted that when the gear position is corrected in this embodiment, the gear position of the outdoor motor is usually lowered.

[0101] An embodiment of the present invention provides a fixed-frequency air conditioner and a motor control method thereof. The fixed-frequency air conditioner includes an indoor unit, an outdoor unit and a controller. The indoor unit is provided with an indoor heat exchanger and an indoor fan; the outdoor unit is provided with an outdoor heat exchanger, an outdoor fan, an outdoor motor, a liquid side temperature sensor of the outdoor heat exchanger, a compressor, a flow regulating valve and a four-way valve. The liquid side temperature sensor of the outdoor heat exchanger is used to detect the temperature of the liquid side of the outdoor heat exchanger. The compressor, the flow regulating valve, the four-way valve, the outdoor heat exchanger and the indoor heat exchanger are connected through pipelines to form a refrigerant circulation loop; the controller is configured to control the outdoor motor to operate at a preset speed when the fixed-frequency air conditioner operates in a heating mode; when it is detected that the temperature of the liquid side temperature sensor of the outdoor heat exchanger reaches below a preset temperature threshold, the current speed of the outdoor motor is corrected according to the target speed of the outdoor motor to obtain the corrected speed, and the outdoor motor is controlled to operate at the corrected speed. The embodiment of the present invention uses the preset temperature threshold of the liquid side temperature sensor of the outdoor heat exchanger as the critical point to correct the rotation speed of the outdoor motor, effectively avoiding the risk of overload damage to the outdoor motor caused by frosting of the outdoor heat exchanger and improving the reliability of motor operation.

[0102] It should be noted that the system embodiment described above is merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. In addition, in the drawings of the system embodiment provided by the present invention, the connection relationship between the modules indicates that there is a communication connection between them, which may be specifically implemented as one or more communication buses or signal lines. A person of ordinary skill in the art may understand and implement it without paying any creative effort.

[0103] The above is a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A fixed frequency air conditioner, characterized in that: include: An indoor unit, which is equipped with an indoor heat exchanger and an indoor fan; An outdoor unit is provided with an outdoor heat exchanger, an outdoor fan, an outdoor motor, a liquid side temperature sensor of the outdoor heat exchanger, a compressor, a flow regulating valve and a four-way valve, wherein the liquid side temperature sensor of the outdoor heat exchanger is used to detect the temperature of the liquid side of the outdoor heat exchanger, and the compressor, the flow regulating valve, the four-way valve, the outdoor heat exchanger and the indoor heat exchanger are connected by pipelines to form a refrigerant circulation loop; A controller, wherein the controller is configured to, when the fixed-frequency air conditioner is running in a heating mode, control the outdoor motor to run at a preset speed; when it is detected that the temperature of the liquid-side temperature sensor of the outdoor heat exchanger reaches below a preset temperature threshold, correct the current speed of the outdoor motor according to the target speed of the outdoor motor to obtain a corrected speed, and control the outdoor motor to run at the corrected speed; Wherein, the controller is further configured as: Calculating a first difference between a target speed and a current speed of the outdoor motor, and determining whether an absolute value of the first difference is not greater than a first threshold; If yes, controlling the outdoor motor to run at the target speed; If not, the target speed of the outdoor motor is added to a first correction value to obtain a corrected speed, and the outdoor motor is controlled to run at the corrected speed; wherein the first correction value is the product of the first difference and a first correction coefficient.

2. The fixed-frequency air conditioner according to claim 1, characterized in that: The controller is configured to: When the fixed-frequency air conditioner operates in a heating mode, controlling the outdoor motor to reach a maximum speed within the first time; After the outdoor motor runs at the maximum speed for a second time, the outdoor motor is controlled to run at a preset speed.

3. The fixed-frequency air conditioner according to claim 2, characterized in that: The controller is also configured to: The current gear position of the outdoor motor is corrected according to the target rotation speed of the outdoor motor and the corrected rotation speed to obtain the corrected gear position.

4. The fixed-frequency air conditioner according to claim 3, characterized in that: The controller is configured to: calculating a second difference between the corrected rotational speed and the target rotational speed, and determining whether an absolute value of the second difference is not greater than a second threshold; If yes, control the outdoor motor to run at the current gear; If not, the current gear of the outdoor motor is added to the second correction value to obtain a corrected gear, and the outdoor motor is controlled to run at the corrected gear; wherein the second correction value is the product of the second difference and the second correction coefficient.

5. A method for controlling a motor of a fixed frequency air conditioner, characterized in that: The method is applied to a fixed-frequency air conditioner including an indoor heat exchanger, an indoor fan, an outdoor heat exchanger, an outdoor fan, an outdoor motor, a liquid-side temperature sensor of the outdoor heat exchanger, a compressor, a flow regulating valve, and a four-way valve. The fixed-frequency air conditioner motor control method includes: When the fixed-frequency air conditioner operates in a heating mode, controlling the outdoor motor to operate at a preset speed; When it is detected that the temperature of the liquid side temperature sensor of the outdoor heat exchanger reaches below a preset temperature threshold, the current speed of the outdoor motor is corrected according to the target speed of the outdoor motor to obtain a corrected speed, and the outdoor motor is controlled to run at the corrected speed; The step of correcting the current speed of the outdoor motor according to the target speed of the outdoor motor to obtain the corrected speed specifically includes: Calculating a first difference between a target speed and a current speed of the outdoor motor, and determining whether an absolute value of the first difference is not greater than a first threshold; If yes, controlling the outdoor motor to run at the target speed; If not, the target speed of the outdoor motor is added to a first correction value to obtain a corrected speed, and the outdoor motor is controlled to run at the corrected speed; wherein the first correction value is the product of the first difference and a first correction coefficient.

6. The method for controlling a motor of a fixed-frequency air conditioner according to claim 5, characterized in that: When the fixed-frequency air conditioner operates in a heating mode, controlling the outdoor motor to operate at a preset speed specifically includes: When the fixed-frequency air conditioner operates in a heating mode, controlling the outdoor motor to reach a maximum speed within the first time; After the outdoor motor runs at the maximum speed for a second time, the outdoor motor is controlled to run at a preset speed.

7. The fixed frequency air conditioner motor control method according to claim 6, characterized in that: The method further comprises: The current gear position of the outdoor motor is corrected according to the target rotation speed of the outdoor motor and the corrected rotation speed to obtain the corrected gear position.

8. The fixed frequency air conditioner motor control method according to claim 7, characterized in that: The step of correcting the current gear position of the outdoor motor according to the target speed of the outdoor motor and the corrected speed to obtain the corrected gear position specifically includes: calculating a second difference between the corrected rotational speed and the target rotational speed, and determining whether an absolute value of the second difference is not greater than a second threshold; If yes, control the outdoor motor to run at the current gear; If not, the current gear of the outdoor motor is added to the second correction value to obtain a corrected gear, and the outdoor motor is controlled to run at the corrected gear; wherein the second correction value is the product of the second difference and the second correction coefficient.

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