Air conditioner

Abstract

The air conditioner comprises an outer rotor motor, and a controller is configured to obtain three-phase currents and a first rotor angle of the inner rotor motor and the outer rotor motor in a first PWM period; performing FOC calculation according to the three-phase current and the first rotor angle, and performing space vector pulse width modulation according to the obtained first target voltage, the second target voltage and the first rotor angle to obtain a first three-phase PWM duty ratio; in the second PWM period, the first target current and the second target current are calculated according to the third target voltage and the FOC, the electrical angular speed of the first PWM period is obtained, and the second rotor angle is obtained according to the electrical angular speed, the first rotor angle and the PWM period; and performing space vector pulse width modulation according to the second rotor angle, the first target voltage and the second target voltage to obtain a second three-phase PWM duty ratio. According to the method, the noise problem of the outer rotor motor can be solved under the condition that the calculation amount is small.

Description

Technical Field

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

[0002] Some existing air conditioners include an external rotor motor in their indoor fan. When the switching frequency of the pulse width modulation (PWM) signal driving the external rotor motor is 16K times / second, that is, the carrier frequency of the external rotor motor is 16kHz, the field-oriented control (FOC) updates the PWM signal by calculating once every two PWM cycles, which will contain a high-frequency component of 8kHz. At this time, the mechanical structure characteristics of the external rotor motor can just convert the 8kHz electrical signal into obvious mechanical vibration, which will produce noise that can be clearly heard by the human ear.

[0003] In related technologies, when the carrier frequency of the external rotor motor is 16kHz, the calculation of FOC is changed from once every two PWM cycles to once every one PWM cycle to update the PWM signal. At this time, the updated PWM signal contains high-frequency components of 16kHz, which are noises that cannot be heard by the human ear. However, because the calculation of FOC is changed from once every two PWM cycles to once every one PWM cycle, the amount of calculation is doubled, and the load on the controller increases. Summary of the Invention

[0004] This application discloses an air conditioner that can solve the noise problem of an external rotor motor with less computation.

[0005] A first aspect of this application discloses an air conditioner, the air conditioner comprising: compressor; An indoor heat exchanger, connected to the compressor, is configured to exchange heat with indoor air via the refrigerant; An outdoor heat exchanger, connected to the compressor, is configured to exchange heat with outdoor air via the refrigerant; The four-way valve includes a first port, a second port, a third port, and a fourth port. The first port is connected to the air outlet of the compressor, the second port is connected to the air inlet of the compressor, the third port is connected to the indoor heat exchanger, and the fourth port is connected to the outdoor heat exchanger. An indoor fan includes an external rotor motor, the stator of which is located inside the external rotor motor and the rotor of which is located outside the external rotor motor, and is configured to rotate under the drive of the external rotor motor to deliver indoor air to the air conditioner after passing through the indoor heat exchanger. The controller, which is electrically connected to both the compressor and the four-way valve, is configured to control the conduction direction of the four-way valve to adjust the flow direction of the refrigerant. The controller is configured as follows: Obtain the three-phase current and the first rotor angle of the external rotor motor during the first pulse width modulation (PWM) cycle; Based on the three-phase current and the first rotor angle, field-oriented control (FOC) calculation is performed to obtain the first target voltage and the first target current along the d-axis of the two-phase rotating coordinate system, and to obtain the second target voltage and the second target current along the q-axis of the two-phase rotating coordinate system, wherein the d-axis is along the magnetic flux direction of the rotor and the q-axis is perpendicular to the d-axis; Space vector pulse width modulation is performed based on the first target voltage, the second target voltage, and the first rotor angle to obtain the first three-phase PWM duty cycle corresponding to the first PWM cycle; In the second PWM cycle, the electric angular velocity of the outer rotor in the first PWM cycle is obtained based on the third target voltage, the first target current and the second target current. The second PWM cycle is the next PWM cycle after the first PWM cycle. The third target voltage is one or both of the first target voltage and the second target voltage. Based on the electrical angular velocity of the first PWM cycle, the first rotor angle, and the PWM cycle, the second rotor angle corresponding to the second PWM cycle is obtained; Space vector pulse width modulation is performed based on the second rotor angle, the first target voltage, and the second target voltage to obtain the second three-phase PWM duty cycle.

[0006] In this scheme, the air conditioner includes a compressor, an indoor heat exchanger, an outdoor heat exchanger, a four-way valve, an indoor fan, and a controller. The indoor fan includes an external rotor motor. The controller is configured to acquire the three-phase current and the first rotor angle of the external rotor in one PWM cycle, perform FOC calculation based on the three-phase current and the first rotor angle, and acquire the first target voltage, the second target voltage, the first target current, and the second target current of the two-phase rotating coordinate system d-axis and q-axis. The first three-phase duty cycle is then acquired based on the first target voltage, the second target voltage, and the first rotor angle. In the second PWM cycle, this scheme does not perform FOC calculation. Instead, it acquires the electric angular velocity of the external rotor in the first PWM cycle based on the third target voltage, the first target current, and the second target current of the previous cycle. The second rotor angle of the second cycle is then acquired based on the electric angular velocity, the first rotor angle, and the PWM cycle. The second three-phase PWM duty cycle is then acquired based on the second rotor angle, the first target voltage, and the second target voltage. As can be seen, this method obtains two three-phase PWM duty cycles within two cycles to update the PWM signal. This ensures that, with a carrier frequency of 16kHz for the external rotor motor, the updated PWM signal only contains the high-frequency component of 16kHz, thus solving the noise problem of the external rotor motor. Furthermore, since performing a complete FOC calculation requires significant computational resources, this solution does not perform a complete FOC calculation in every cycle, but only in the first cycle of the two cycles. In the second cycle, the electrical angular velocity is obtained based on the parameters of the previous cycle. Because the electrical angular velocity and voltage remain essentially unchanged within a short time, the second rotor angle of the second cycle can be obtained from this electrical angular velocity. The second three-phase PWM duty cycle of the second cycle can then be obtained from this second rotor angle, the first target voltage, and the second target voltage, significantly reducing computational resources. Therefore, this solution can solve the noise problem of the external rotor motor with less computation.

[0007] As an optional implementation, in a first aspect of this embodiment, the external rotor motor further includes a permanent magnet, and the controller is configured to: Obtain target parameters, including the magnetic flux linkage of the permanent magnet, the stator resistance, the first inductance of the d-axis of the two-phase rotating coordinate system, and the second inductance of the q-axis of the two-phase rotating coordinate system; Based on the voltage equation of the external rotor motor, obtain the logical relationship between the electric angular velocity and the third target voltage, the first target current, the second target current, and the target parameters; The electric angular velocity is obtained based on the logical relationship described above.

[0008] In this scheme, the controller first obtains the key target parameters of the motor, including the permanent magnet flux linkage, stator resistance, the first inductance of the d-axis and the second inductance of the q-axis in the two-phase rotating coordinate system. Then, based on the voltage equation of the external rotor motor, it establishes the logical relationship between the electric angular velocity and the third target voltage, the first target current, the second target current and the above target parameters. Finally, the electric angular velocity is calculated based on the logical relationship.

[0009] This method constructs a logical relationship based on the motor voltage equation, an essential model reflecting electromagnetic relationships, ensuring the theoretical accuracy of electric angular velocity calculation. It can provide a reliable basis for precise speed regulation and torque control of external rotor motors.

[0010] As an optional implementation, in a first aspect of this embodiment, the controller is configured to: Obtain the product of the electrical angular velocity and the PWM period; Obtain the sum of the product and the first rotor angle, where the sum is the second rotor angle.

[0011] In this scheme, the controller obtains the product of the electrical angular velocity and the PWM period, then adds this product to the first rotor angle, and the sum is the second rotor angle, thus realizing the calculation and update of the rotor angle. This method can efficiently complete the second rotor angle update for the next PWM cycle based on one PWM cycle, thereby obtaining the second three-phase PWM duty cycle for the next cycle without performing complex FOC calculations. This reduces the computational load and also achieves the acquisition of the three-phase duty cycle signal in each PWM cycle to update the PWM signal, thus solving the noise problem.

[0012] As an optional implementation, in a first aspect of this embodiment, the controller is configured to: Based on the second rotor angle, perform an inverse Park transformation on the first target voltage and the second target voltage to obtain the first voltage along the α axis of the two-phase stationary coordinate system and the second voltage along the β axis of the two-phase stationary coordinate system. The magnitude and angle of the first spatial voltage vector are obtained based on the first voltage and the second voltage. The duty cycle of the second three-phase PWM is obtained based on the magnitude and angle of the first space voltage vector.

[0013] In this scheme, the first and second target voltages are first subjected to an inverse Park transformation based on the second rotor angle to obtain the first voltage along the α-axis and the second voltage along the β-axis of the two-phase stationary coordinate system. Then, the amplitude and angle of the first spatial voltage vector are determined based on these two voltages. Finally, the duty cycle of the second three-phase PWM is calculated based on the amplitude and angle of this spatial voltage vector. This method achieves precise coordinate system transformation through the inverse Park transformation and calculates the duty cycle using the amplitude and angle of the spatial voltage vector. This conforms to the theoretical logic of voltage vector modulation in motor control, accurately reflects the correspondence between the motor voltage demand and the spatial vector, provides an accurate basis for PWM signal generation, and has clear steps that are easy to implement in engineering.

[0014] As an optional implementation, in a first aspect of this embodiment, the controller is configured to: The three-phase currents are subjected to Clark transformation to obtain the first current along the α-axis of the two-phase stationary coordinate system and the second current along the β-axis of the two-phase stationary coordinate system. The first current, the second current, and the first rotor angle are subjected to Park transformation to obtain the first target current on the d-axis of the two-phase rotating coordinate system and the second target current on the q-axis of the two-phase rotating coordinate system. The first target current and the second target current are processed by a current loop PI regulator to obtain the first target voltage and the second target voltage.

[0015] In this scheme, the three-phase currents are first subjected to Clark transformation to obtain the first current along the α-axis and the second current along the β-axis in a two-phase stationary coordinate system. Then, combined with the first rotor angle, these two currents are subjected to Park transformation to obtain the first target current along the d-axis and the second target current along the q-axis in a two-phase rotating coordinate system. Finally, a current-loop PI regulator processes these two target currents to output the first target voltage and the second target voltage. This method achieves accurate conversion from three-phase current to two-phase rotating coordinate system current through Clark and Park transformations, which conforms to the theoretical framework of motor vector control. Furthermore, the closed-loop control of the first and second target currents by the PI regulator provides a reliable basis for obtaining the PWM signal of the external rotor motor.

[0016] As an optional implementation, in a first aspect of this embodiment, the controller is configured to: The first target error is obtained based on the first preset current of the d-axis of the set two-phase rotating coordinate system and the first target current. The first target voltage is obtained based on the set scaling factor of the d-axis of the two-phase rotating coordinate system, the set integral factor of the d-axis of the two-phase rotating coordinate system, and the first target error; and, The second target error is obtained based on the second preset current of the q-axis of the set two-phase rotating coordinate system and the second target current. The second target voltage is obtained based on the set scaling factor of the q-axis of the two-phase rotating coordinate system, the set integral factor of the q-axis of the two-phase rotating coordinate system, and the second target error.

[0017] In this scheme, the first target error is obtained by calculating the difference between the first preset current and the first target current on the d-axis of the two-phase rotating coordinate system. This error is then processed using the proportional and integral coefficients set for the d-axis to obtain the first target voltage. Simultaneously, the second target error is obtained by calculating the difference between the second preset current and the second target current on the q-axis. This error is also processed using the proportional and integral coefficients set for the q-axis to obtain the second target voltage. This method employs a split-axis independent PI control strategy, with the d-axis and q-axis adjusted separately based on the error between their own preset current and the actual current. This allows for targeted optimization of the control performance of each axis. Furthermore, the flexible setting of the proportional and integral coefficients quickly eliminates current errors, improving the accuracy and dynamic response of current control.

[0018] As an optional implementation, in a first aspect of this embodiment, the air conditioner further includes a sensor. The sensor, connected to the external rotor motor, is configured to acquire the first rotor angle; The sensor is also communicatively connected to the controller, which is configured to: The first rotor angle is obtained through the sensor.

[0019] In this scheme, the air conditioner's sensor is connected to the external rotor motor to obtain the first rotor angle. The sensor also communicates with the controller, which uses this sensor to acquire the first rotor angle, thus collecting the initial rotor angle information. This method directly obtains the first rotor angle through the sensor, ensuring the real-time nature and accuracy of the angle information. This provides reliable initial data support for subsequent motor control processes such as Park transformation and rotor angle updates. Furthermore, the communication connection between the sensor and the controller makes angle information transmission efficient and direct, eliminating the need for complex indirect calculations, simplifying the control logic, and improving the overall accuracy and stability of the external rotor motor control.

[0020] As an optional implementation, in the first aspect of this embodiment, the sensor is an encoder. The encoder is configured to acquire the rotational position information of the rotor of the external rotor motor. The controller is configured to: The encoder is used to obtain the rotational position information, and the rotational position information is processed to obtain the first rotor angle.

[0021] In this scheme, the air conditioner uses an encoder as a sensor to acquire the rotational position information of the external rotor motor. The controller obtains and processes this rotational position information through the encoder to obtain the first rotor angle. This method uses an encoder as a high-precision position detection element, which can accurately acquire rotor rotational position information, providing high-quality raw data for calculating the first rotor angle and ensuring the accuracy of the angle information. Furthermore, the controller's processing of the position information can further optimize the angle result to meet the accuracy requirements of motor control. In addition, the encoder's real-time detection characteristics can promptly reflect changes in rotor position, providing a fast-response position basis for the dynamic control of the external rotor motor and improving overall control performance.

[0022] As an optional implementation, in the first aspect of this embodiment, the sensor is a rotary transformer. The rotary transformer is configured to obtain the induced electromotive force of the stator and rotor of the external rotor motor when they are in an electromagnetic coupling state. The controller is configured to: The induced electromotive force is obtained through the rotary transformer, and the induced electromotive force is processed to obtain the first rotor angle.

[0023] In this scheme, a rotary transformer is used as the sensor to acquire the induced electromotive force (EMF) when the stator and rotor of the external rotor motor are in an electromagnetic coupling state. The controller acquires and processes this induced EMF through the rotary transformer to obtain the first rotor angle. The rotary transformer has strong anti-interference capabilities and environmental adaptability, and can stably acquire the induced EMF even under harsh operating conditions, providing a reliable raw signal for calculating the first rotor angle. The rotor angle obtained by processing the induced EMF conforms to the physical characteristics of electromagnetic coupling, ensuring the accuracy of the angle information. Furthermore, the rotary transformer has a robust and durable structure, allowing for long-term stable operation, which helps improve the reliability and service life of the external rotor motor control system.

[0024] As an optional implementation, in the first aspect of this embodiment, the sensor is a Hall sensor. The Hall sensor is configured to convert the magnetic field information of the external rotor motor when the rotor is rotating into a discrete electrical signal. The controller is configured to: The discrete electrical signal is acquired through the Hall sensor, and the discrete electrical signal is processed to obtain the first rotor angle.

[0025] In this scheme, a Hall sensor is used, which converts the magnetic field information of the external rotor motor's rotor rotation into discrete electrical signals. The controller acquires and processes these discrete electrical signals through the Hall sensor to obtain the first rotor angle. The Hall sensor is simple in structure and low in cost, making it suitable for large-scale applications. Its characteristic of converting magnetic field information into discrete electrical signals simplifies the signal processing process, enabling it to quickly provide the controller with rotor position-related information. Simultaneously, the Hall sensor has a fast response speed, promptly reflecting the rotor's rotational state and meeting the basic real-time requirements of motor control. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a spectrum diagram of the fitted waveform output of a controller disclosed in an embodiment of this application; Figure 2 This is a schematic structural diagram of an air conditioner disclosed in an embodiment of this application; Figure 3 This is a flowchart of a control method for a controller disclosed in an embodiment of this application; Figure 4 A waveform diagram illustrating an SVPWM update strategy provided in an embodiment of this application; Figure 5 A schematic diagram of fitting a voltage vector to a vector circle within a circle, provided as an embodiment of this application; Figure 6 This is a flowchart of another controller control method disclosed in an embodiment of this application; Figure 7 This is a flowchart of another controller control method disclosed in an embodiment of this application; Figure 8 This is a flowchart of another controller control method disclosed in an embodiment of this application; Figure 9 This is a flowchart of another controller control method disclosed in an embodiment of this application; Figure 10 This is a flowchart of another controller control method disclosed in an embodiment of this application. Detailed Implementation

[0028] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0029] It should be noted that the terms "first, second, third" used in the embodiments of this application are used to distinguish similar or different objects and do not represent a specific order of objects. It can be understood that "first, second, third" can be interchanged in a specific order or sequence where permitted, so that the embodiments of this application described herein can be implemented in an order other than that illustrated or described herein.

[0030] In current air conditioner indoor fan design, external rotor motors are widely used due to their compact structure and good heat dissipation. Their operation relies on pulse width modulation (PWM) signals, and the switching frequency of the PWM signal directly affects the stability of motor control and operating noise. When the PWM switching frequency of the external rotor motor is set to 16K times / second (i.e., a carrier frequency of 16kHz), some industry solutions use Field-Oriented Control (FOC) algorithms to update the PWM signal. By default, the FOC calculation cycle is matched to the PWM cycle in a "two-to-one" manner, meaning that an FOC calculation and PWM signal update is performed only once every two PWM cycles. From the perspective of signal frequency characteristics, this two-cycle calculation update mode inevitably results in the final output PWM signal containing a high-frequency component of 8kHz. This is because the FOC calculation cycle is twice the PWM cycle, and its signal update frequency of 8kHz is exactly half the PWM carrier frequency.

[0031] For example, such as Figure 1 The above, Figure 1 This is a spectrum diagram of the fitted waveform output of a controller disclosed in an embodiment of this application, wherein, Figure 1 (a) is a spectrum diagram of an ideally fitted waveform output by a controller disclosed in an embodiment of this application. Figure 1 (b) is a spectrum diagram of the fitted waveform with an update frequency of 8kHz output by a controller according to an embodiment of this application. As can be seen from the figure, at an update frequency of 8kHz, the fundamental signal generated by the controller is a non-ideal continuous waveform. That is, when the update frequency of the PWM signal is 8kHz, the spectrum of the fitted waveform output by the corresponding controller also has a high-frequency component of 8kHz, i.e., as shown... Figure 1(b) shows the discontinuous sawtooth pattern 10. The core issue lies in the resonance matching between the mechanical structural characteristics of the external rotor motor and this high-frequency component. That is, the rotor, bearings, and other mechanical components of the external rotor motor have specific natural frequencies. When an 8kHz electrical signal is transmitted to the mechanical structure, it resonates with the natural frequencies of some components, thereby converting the electrical signal energy into obvious mechanical vibration. The frequency of this vibration is within the range of human hearing, and the amplitude is sufficient to be perceived by the human body, ultimately manifesting as a "humming" or "whistling" sound that the user can clearly hear, seriously affecting the user experience of the air conditioner.

[0032] To address this noise issue, a proposed optimization scheme adjusts the FOC calculation cycle: while maintaining the PWM carrier frequency at 16kHz, the FOC calculation is changed from once every two PWM cycles to once per PWM cycle, meaning the FOC calculation is completely synchronized with the PWM signal cycle. In this case, the PWM signal update frequency and the FOC calculation frequency are identical at 16kHz, increasing the high-frequency component frequency in the output PWM signal to 16kHz. Since 16kHz is close to the upper limit of the human ear's audible range, and the sensitivity of the human auditory system to high-frequency sounds decreases significantly with increasing frequency, mechanical vibrations at 16kHz, once converted into noise, are essentially imperceptible to the human ear, effectively eliminating audible noise. However, this scheme presents a significant performance trade-off: the OC algorithm itself involves very complex calculations. Changing the calculation from once every two PWM cycles to once per PWM cycle directly doubles the computational load the controller needs to process per unit time. This leads to a significant increase in the controller's CPU load, potentially causing two risks: First, if the controller's processing speed is insufficient, FOC calculations may be delayed, resulting in untimely PWM signal updates, which in turn affects motor control accuracy, causing problems such as speed fluctuations and unstable torque. Second, prolonged high-load operation will increase the controller's power consumption and heat generation, shortening its lifespan and potentially triggering overheat protection, causing the air conditioner to shut down. Therefore, while this solution addresses the noise issue, it places higher demands on the controller's hardware performance, requiring a new balance to be found between noise control and controller load.

[0033] To address the noise problem of external rotor motors with minimal computational effort, this application discloses an air conditioner comprising a compressor. An indoor heat exchanger, connected to the compressor, is configured to exchange heat with indoor air via the refrigerant; An outdoor heat exchanger, connected to the compressor, is configured to exchange heat with outdoor air via the refrigerant; The four-way valve includes a first port, a second port, a third port, and a fourth port. The first port is connected to the air outlet of the compressor, the second port is connected to the air inlet of the compressor, the third port is connected to the indoor heat exchanger, and the fourth port is connected to the outdoor heat exchanger. An indoor fan includes an external rotor motor, the stator of which is located inside the external rotor motor and the rotor of which is located outside the external rotor motor, and is configured to rotate under the drive of the external rotor motor to deliver indoor air to the air conditioner after passing through the indoor heat exchanger. The controller, which is electrically connected to both the compressor and the four-way valve, is configured to control the conduction direction of the four-way valve to adjust the flow direction of the refrigerant. The controller is configured as follows: Obtain the three-phase current and the first rotor angle of the external rotor motor during the first pulse width modulation (PWM) cycle; Based on the three-phase current and the first rotor angle, field-oriented control (FOC) calculation is performed to obtain the first target voltage and the first target current along the d-axis of the two-phase rotating coordinate system, and to obtain the second target voltage and the second target current along the q-axis of the two-phase rotating coordinate system, wherein the d-axis is along the magnetic flux direction of the rotor and the q-axis is perpendicular to the d-axis; Space vector pulse width modulation is performed based on the first target voltage, the second target voltage, and the first rotor angle to obtain the first three-phase PWM duty cycle corresponding to the first PWM cycle; In the second PWM cycle, the electric angular velocity of the outer rotor in the first PWM cycle is obtained based on the third target voltage, the first target current and the second target current. The second PWM cycle is the next PWM cycle after the first PWM cycle. The third target voltage is one or both of the first target voltage and the second target voltage. Based on the electrical angular velocity of the first PWM cycle, the first rotor angle, and the PWM cycle, the second rotor angle corresponding to the second PWM cycle is obtained; Space vector pulse width modulation is performed based on the second rotor angle, the first target voltage, and the second target voltage to obtain the second three-phase PWM duty cycle.

[0034] In this scheme, the air conditioner includes a compressor, an indoor heat exchanger, an outdoor heat exchanger, a four-way valve, an indoor fan, and a controller. The indoor fan includes an external rotor motor. The controller is configured to acquire the three-phase current and the first rotor angle of the external rotor in one PWM cycle, perform FOC calculation based on the three-phase current and the first rotor angle, and acquire the first target voltage, the second target voltage, the first target current, and the second target current of the two-phase rotating coordinate system d-axis and q-axis. The first three-phase duty cycle is then acquired based on the first target voltage, the second target voltage, and the first rotor angle. In the second PWM cycle, this scheme does not perform FOC calculation. Instead, it acquires the electric angular velocity of the external rotor in the first PWM cycle based on the third target voltage, the first target current, and the second target current of the previous cycle. The second rotor angle of the second cycle is then acquired based on the electric angular velocity, the first rotor angle, and the PWM cycle. The second three-phase PWM duty cycle is then acquired based on the second rotor angle, the first target voltage, and the second target voltage. As can be seen, this method obtains two three-phase PWM duty cycles within two cycles to update the PWM signal. This ensures that, with a carrier frequency of 16kHz for the external rotor motor, the updated PWM signal only contains the high-frequency component of 16kHz, thus solving the noise problem of the external rotor motor. Furthermore, since performing a complete FOC calculation requires significant computational resources, this solution does not perform a complete FOC calculation in every cycle, but only in the first cycle of the two cycles. In the second cycle, the electrical angular velocity is obtained based on the parameters of the previous cycle. Because the electrical angular velocity and voltage remain essentially unchanged within a short time, the second rotor angle of the second cycle can be obtained from this electrical angular velocity. The second three-phase PWM duty cycle of the second cycle can then be obtained from this second rotor angle, the first target voltage, and the second target voltage, significantly reducing the consumption of computational resources. Therefore, this solution can solve the noise problem of the external rotor motor with less computation.

[0035] The air conditioner refrigerator provided in this application will be described in detail below with reference to the accompanying drawings and embodiments, so as to make the purpose and technical solution of this application clearer and more intuitive. It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application.

[0036] It is understood that the air conditioners provided in the embodiments of this application include, but are not limited to, wall-mounted air conditioners, cabinet air conditioners, built-in air conditioners, duct air conditioners, window air conditioners, and portable air conditioners.

[0037] Please see Figure 2 , Figure 2 This is a schematic diagram of the structure of an air conditioner provided in an embodiment of this application. Figure 1As shown, the air conditioner 100 may include a compressor 11, a gas-liquid separator 12, an outdoor heat exchanger 13, an outdoor fan 14, a four-way valve 15, an indoor heat exchanger 22, an indoor fan 21, an indoor fan 23, and an external rotor motor 24. The compressor 11, gas-liquid separator 12, outdoor heat exchanger 13, outdoor fan 14, and four-way valve 15 constitute the outdoor unit of the air conditioner, while the indoor heat exchanger 22, indoor fan 21, indoor fan 23, and external rotor motor 24 constitute the indoor unit. The indoor unit is located indoors, and the outdoor unit is located outdoors, connected by a refrigerant flow channel.

[0038] In some embodiments, the compressor 11 in the outdoor unit has an air inlet and an air outlet. Refrigerant can flow out from the air outlet of the compressor 11 to flow to other components of the air conditioner 100. Additionally, refrigerant can also flow back into the compressor 11 from the air inlet to complete the refrigerant cycle.

[0039] In some embodiments, the gas-liquid separator 12 in the outdoor unit is disposed between the four-way valve 15 and the air inlet of the compressor 11, for separating liquid refrigerant and gaseous refrigerant, thereby collecting liquid refrigerant and transferring gaseous refrigerant to the air inlet of the compressor 11.

[0040] In this embodiment, the indoor heat exchanger 22 of the indoor unit is connected to the compressor 11 and is used for heat exchange between the refrigerant flowing out of the compressor 11 and the indoor air. This allows the indoor heat exchanger 22 to absorb heat from the room, thereby achieving indoor cooling, or it can release heat into the room, thereby achieving indoor heating. The indoor heat exchanger 22 may include a plate heat exchanger or a coaxial heat exchanger.

[0041] In some embodiments, the outdoor heat exchanger 13 of the outdoor unit is also connected to the compressor 11 for heat exchange with the outdoor air. The outdoor heat exchanger 13 may include a tube-fin heat exchanger, a plate heat exchanger, or a shell-and-tube heat exchanger, etc., so that the outdoor heat exchanger 13 can absorb the heat of the outdoor air or release the heat of the refrigerant into the outdoor air.

[0042] In some embodiments, during the heat exchange process between the outdoor heat exchanger 13 and the outdoor air, the refrigerant may first exchange heat with the target medium, and then the target medium may exchange heat with the outdoor air. The target medium may include water, brine solution, refrigerant, or antifreeze, such as Freon for refrigerant and ethylene glycol solution for antifreeze. Alternatively, the refrigerant may directly exchange heat with the outdoor air. The specific settings are determined by the user according to the actual situation, and this application embodiment does not impose any limitations.

[0043] In some embodiments, the outdoor fan 14 of the outdoor unit is disposed on one side of the outdoor heat exchanger 13, for transmitting outside air to the outdoor heat exchanger 13 through the second return air vent of the air conditioner 100 housing, and transmitting the air flowing through the outdoor heat exchanger 13 to the outside through the second air outlet of the air conditioner 100 housing. The second air outlet is an opening on the air conditioner 100 housing corresponding to the position of the outdoor fan 14, and the second return air vent is an opening on the air conditioner 100 housing corresponding to the position of the outdoor fan 14. The positions of the second air outlet and the second return air vent are different.

[0044] It is understandable that the outdoor fan 14 is located close to the outdoor heat exchanger 13. The outdoor fan 14 may include a first fan and an outdoor fan 14 motor. The first fan is fixedly mounted on the rotating shaft of the outdoor fan 14 motor. The outdoor fan 14 motor is connected to the controller of the air conditioner 100 so that the first fan is driven to rotate under the control of the controller so as to transfer outdoor air to the outdoor heat exchanger 13 and realize heat exchange between the outdoor heat exchanger 13 and the outdoor air.

[0045] The first end of the indoor heat exchanger 22 is connected to the first end of the outdoor heat exchanger 13. In this way, the refrigerant can flow from the first end of the outdoor heat exchanger 13 to the indoor heat exchanger 22, or the refrigerant can flow from the first end of the indoor heat exchanger 22 to the outdoor heat exchanger 13. This allows the mode of the air conditioner 100 to be switched so that the indoor heat exchanger 22 can act as a condenser or an evaporator, thereby achieving indoor cooling, heating or defrosting.

[0046] In some embodiments, during the heat exchange process between the indoor heat exchanger 22 and the indoor air, the refrigerant may first exchange heat with the target medium, and then the target medium may exchange heat with the indoor air. The target medium may include water, brine solution, refrigerant, or antifreeze, etc. For example, refrigerant is Freon, and antifreeze is ethylene glycol solution. Alternatively, the refrigerant may directly exchange heat with the indoor air. The specific settings are determined by the user according to the actual situation, and this application embodiment does not impose any limitations.

[0047] In some embodiments, the indoor fan 21 of the indoor unit is disposed on one side of the indoor heat exchanger 22, for transmitting outside air to the indoor heat exchanger 22 through the first return air vent of the air conditioner 100 housing, and transmitting the air flowing through the indoor heat exchanger 22 to the outside through the first air outlet of the air conditioner 100 housing. The first air outlet is an opening on the air conditioner 100 housing corresponding to the position of the indoor fan 21, and the first return air vent is an opening on the air conditioner 100 housing corresponding to the position of the indoor fan 21. The positions of the first air outlet and the first return air vent are different.

[0048] It is understood that the indoor fan 21 is located close to the indoor heat exchanger 22. The indoor fan 21 may include a second fan and an indoor fan 21 motor. The second fan is fixedly mounted on the rotating shaft of the indoor fan 21 motor. The indoor fan 21 motor is connected to the controller of the air conditioner 100 so that the second fan is driven to rotate under the control of the controller so as to transfer indoor air to the indoor heat exchanger 22 and realize heat exchange between the indoor heat exchanger 22 and the indoor air.

[0049] In some embodiments, the four-way valve 15 of the outdoor unit is connected to the controller to adjust the conduction direction under the control of the controller so that the air conditioner 100 operates in cooling mode, heating mode or defrosting mode.

[0050] In some embodiments, the four-way valve 15 includes a first port 153, a second port 151, a third port 154, and a fourth port 152. The first port 153 is connected to the outlet of the compressor 11, the second port 151 is connected to the inlet of the compressor 11, the third port 154 is connected to the indoor heat exchanger 22, and the fourth port 152 is connected to the outdoor heat exchanger 13. The controller can control the direction of refrigerant flow by controlling the conduction direction of the four-way valve 15, thereby making one of the outdoor heat exchanger 13 and the indoor heat exchanger 22 act as a condenser and the other as an evaporator.

[0051] In some embodiments, the indoor fan 23 of the indoor unit is arranged adjacent to the indoor heat exchanger 22 and is a functional unit for realizing "airflow circulation and heat exchange drive". It may include, but is not limited to, an external rotor motor 24, a fan wheel, a bearing and a fixed bracket, etc., and is used to convert motor power into directional airflow under the drive of the external rotor motor 24, so as to push indoor air to flow through the indoor heat exchanger 22 to complete heat exchange.

[0052] Among them, the external rotor motor 24 is the only power source of the indoor fan 23. Its stator is located inside the external rotor motor 24, and its rotor is located outside the external rotor motor 24. It directly drives the impeller to rotate and is the core component for realizing airflow power in the indoor fan 23. Without the external rotor motor 24, the indoor fan 23 is just a static impeller and support, and cannot generate any airflow.

[0053] In some embodiments, the stator of the external rotor motor 24 is fixed on the bracket of the indoor fan 23 and is made of stacked silicon steel sheets with copper wire windings wound around its surface. When energized, it generates a rotating magnetic field. The rotor of the external rotor motor 24 is an annular sleeve-shaped structure that wraps around the outside of the stator. Permanent magnets are attached to the inner wall of the rotor, which drives the rotor to rotate around the stator under the action of the rotating magnetic field of the stator. In some embodiments, the air conditioner further includes a controller (not shown in the figure), which is electrically connected to the compressor 11 and the four-way valve 15 respectively, and is configured to control the conduction direction of the four-way valve 15 to adjust the flow direction of the refrigerant.

[0054] In other embodiments, the controller of the air conditioner is also connected to the external rotor motor 24 of the indoor fan 23, and can control the indoor fan 23 according to user settings, such as wind speed or temperature.

[0055] For example, the controller can also calculate the target speed of the external rotor motor 24 according to user settings, such as wind speed or temperature, using the FOC algorithm, and convert the speed command into a PWM signal, which is transmitted to the drive circuit of the external rotor motor 24 through wires. After receiving the PWM signal, the drive circuit of the external rotor motor 24 outputs three-phase AC power of different frequencies to the stator winding. The stator generates a rotating magnetic field, and the rotor rotates around the stator under the action of the magnetic field force. Since the impeller is directly fixed on the rotor shaft, the rotor rotates synchronously with the impeller. The blades of the impeller push the indoor air through the indoor heat exchanger 22 to complete the heat exchange through the action of centrifugal force and axial thrust.

[0056] Optionally, the air conditioner controller may include mechanical controllers, electronic controllers, proportional-integral-derivative controllers, frequency converters, and intelligent controllers, etc. No specific restrictions are imposed here, and the appropriate type can be selected according to the actual situation.

[0057] Based on the schematic structural diagram of the air conditioner disclosed in the embodiments of this application, in order to solve the noise problem of the external rotor motor 24 with less computation, please refer to... Figure 3 , Figure 3 This is a flowchart of a control method for a controller disclosed in an embodiment of this application. The flowchart includes at least the following steps S101-S106.

[0058] Step S101: The controller acquires the three-phase current of the rotor motor 24 and the first rotor angle during the first pulse width modulation (PWM) cycle; The pulse width modulation (PWM) period is a core parameter of a PWM signal. A PWM signal is a digital waveform that simulates a continuously changing signal by periodically changing the duration of pulse high or low levels. Its characteristics are defined by several core parameters, such as the PWM period, PWM frequency, and duty cycle.

[0059] The PWM period refers to a complete pulse cycle, that is, the total time from the start of a high level to the start of the next high level, usually measured in seconds, milliseconds, or microseconds. For example, if a PWM signal completes a high-to-low and low-to-high cycle every 0.0000625 seconds, its PWM period is 62.5 microseconds. It should be understood that this description of the PWM period size is merely an example and does not constitute a specific limitation.

[0060] PWM frequency is the number of pulse cycles per unit time, and it is the reciprocal of the period, measured in Hertz (Hz). For example, when the PWM period T = 62.5 microseconds, the frequency f = 1 / 62 microseconds = 16 kHz, meaning it completes 16,000 pulse cycles per second. It should be understood that this description of PWM frequency is merely an example and does not constitute a specific limitation.

[0061] Duty cycle is a core control parameter of PWM signals, referring to the ratio of the duration of the high level ("") to the total time of the cycle, usually expressed as a percentage (%). For example, a duty cycle of 50% means that the high and low levels each occupy half of a cycle. It should be understood that this description of duty cycle is merely an example and does not constitute a specific limitation.

[0062] In some embodiments, the average output voltage can be precisely adjusted by changing the duty cycle. For example, when the high level is 5V and the duty cycle is 60%, the average output voltage U = 5V × 60% = 3V, achieving the effect of simulating a continuous 3V voltage with a 5V digital signal. It is understood that the above description is merely an example and is not intended to impose specific limitations.

[0063] In one embodiment, the three-phase current relies on a three-phase AC power supply—that is, three sinusoidal AC currents with the same frequency, equal amplitude, and a 120° phase difference—to form the current in a three-phase load, such as a motor, transformer, or industrial equipment. Its waveform is synchronized with the drive power supply and also satisfies the symmetrical characteristics of "consistent frequency, equal amplitude, and a 120° phase difference." It connects to the load using either a star or delta connection. In a star (Y) configuration, the line current equals the phase current, and a neutral line can be used to adapt to single-phase equipment. In a delta configuration, the line current equals √3 × phase current. Using three-phase current not only results in high power transmission efficiency and stable power output but also allows for smaller, more compact three-phase loads with superior starting performance.

[0064] In some embodiments, the three-phase current of the external rotor motor 24 can be obtained through sampling resistors. A small-value precision resistor can be connected in series in each phase circuit as a sampling resistor to convert the three-phase current signal into a voltage signal. After being amplified by a differential amplifier, it is converted into a digital signal by an analog-to-digital converter and sent to the controller.

[0065] In other embodiments, a current transformer can also be used to obtain the three-phase current of the external rotor motor 24. A suitable model of current transformer is selected according to the rated current and measurement accuracy of the external rotor motor 24, and it is connected to the external rotor motor 24. The output terminal is connected to an ammeter or data acquisition instrument to obtain the current value of the three-phase current.

[0066] In other embodiments, the characteristic that the sum of the three-phase currents is zero can be utilized to measure the current of any two phases using a current transformer or a sampling resistor, and the value of the third-phase current can be derived.

[0067] It is understood that the above method for obtaining the three-phase current of the external rotor motor 24 is only an example, and other methods can also be used to obtain the three-phase current of the external rotor motor 24. No specific restrictions are made here.

[0068] In this embodiment, the rotor angle of the external rotor motor 24 refers to the angular position of the magnetic field of the motor rotor relative to the magnetic field of the stator winding. Its relationship with the mechanical angle is: rotor angle = number of pole pairs × mechanical angle, where the mechanical angle refers to the actual physical angle of the rotor's rotation relative to the stator.

[0069] In some embodiments, the first rotor angle can be obtained through a sensor method. For example, an incremental encoder or an absolute encoder can be used to directly measure the mechanical angle, and then the first rotor angle can be calculated based on the relationship between the rotor angle and the mechanical angle. Alternatively, a Hall sensor can be used to acquire the rotor position signal of the external rotor motor 24, and the first rotor angle can be estimated by interpolating the output position signal.

[0070] In other embodiments, the first rotor angle can be obtained using sensorless algorithms. For example, the rotor angle can be derived by detecting the back electromotive force of the windings and using algorithms such as phase-locked loops to track the zero-crossing point of the back electromotive force. Alternatively, model prediction methods such as sliding mode observers and extended Kalman filters can be used to indirectly solve for the first rotor angle using the mathematical model of the motor. Another example is that the initial value of the first rotor angle can be calculated based on the rotor response by injecting DC current into the stator windings of the external rotor motor 24.

[0071] It is understood that the above method for obtaining the first rotor angle of the external rotor motor 24 is only an example, and other methods can also be used to obtain the first rotor angle of the external rotor motor 24. No specific restrictions are made here.

[0072] Step S102: The controller performs field-oriented control (FOC) calculation based on the three-phase current and the first rotor angle to obtain the first target voltage and the first target current of the two-phase rotating coordinate system d-axis, and the second target voltage and the second target current of the two-phase rotating coordinate system q-axis. The d-axis is along the rotor flux linkage direction, and the q-axis is perpendicular to the d-axis. In some embodiments, the core of the field-oriented control (FOC) calculation is to achieve the decoupling of the excitation components of the three-phase current of the stator of the external rotor motor 24, namely the first target current of the d-axis and the torque components, namely the second target current of the q-axis, through coordinate transformation and closed-loop adjustment.

[0073] In the two-phase rotating coordinate system, the rotational speed and direction of the rotor magnetic field of the external rotor motor 24 are used as the reference, and it rotates synchronously with the rotor. The coordinate system contains two mutually perpendicular axes: the d-axis is along the rotor flux direction and is mainly used to control the first target current of the d-axis of the external rotor motor; the q-axis is perpendicular to the d-axis and leads the rotor rotation direction by 90° electrical angle and is mainly used to control the second target current of the external rotor motor 24.

[0074] In some embodiments, the FOC calculation process may include: first, using Clark transformation to convert the three-phase current in the three-phase stationary coordinate system into the α-axis current and β-axis current in the two-phase stationary coordinate system; then, combining the first rotor angle, using Park transformation to convert the α-axis current and β-axis current in the two-phase stationary coordinate system into the first target current of the d-axis in the synchronous rotating coordinate system, and obtaining the second target current of the q-axis in the two-phase rotating coordinate system, at which point the decoupling from excitation to torque components is completed; subsequently, comparing the first target current of the d-axis and the second target current of the q-axis with their respective given values ​​to generate the first target voltage of the d-axis and the first target voltage of the q-axis.

[0075] Step S103: The controller performs space vector pulse width modulation based on the first target voltage, the second target voltage, and the first rotor angle to obtain the first three-phase PWM duty cycle corresponding to the first PWM cycle; In some embodiments, Space Vector Pulse Width Modulation (SVPWM) refers to the use of different conduction combinations of the six power switches in an air conditioner's inverter to correspond to eight basic space voltage vectors, including two zero vectors and six non-zero vectors.

[0076] For example, SVPWM can be implemented as follows: First, the controller determines the amplitude and phase of the corresponding space voltage vector in a two-phase stationary coordinate system based on the first and second target voltages. This clarifies the vector's position in a vector space composed of six non-zero basic voltage vectors (distributed at 60-degree electrical angle intervals to form a hexagon) and two zero vectors. Next, by determining the sector where the target vector is located, two adjacent non-zero basic vectors within that sector are selected. Based on the principle of vector composition—that the target vector equals the superposition of two adjacent basic vectors at a specific time ratio—the respective durations of these two non-zero vectors within the current PWM cycle are calculated. Simultaneously, the duration of the zero vector is determined based on the difference between the total PWM cycle duration and the durations of the two non-zero vectors, ensuring that the voltage vector synthesis effect more closely approximates a circular trajectory and reducing switching losses. Finally, these calculated time parameters are converted into the on / off time ratio of the power switches in the inverter, yielding the three-phase PWM duty cycle corresponding to the first PWM cycle, thereby controlling the inverter to output a three-phase AC voltage that meets the motor's requirements. Compared to traditional sinusoidal pulse width modulation, SVPWM can improve bus voltage utilization and reduce switching losses.

[0077] In this embodiment, the controller first acquires the first target voltage, the second target voltage, and the first rotor angle. Then, based on these parameters, it executes the SVPWM algorithm to convert the first target voltage and the second target voltage into the first three-phase PWM duty cycle of the three-phase output signal corresponding to the first PWM cycle. This duty cycle is then used to turn the inverter switching transistors of the controller on and off, thereby enabling precise adjustment of the stator winding voltage of the external rotor motor 24.

[0078] Step S104: In the second PWM cycle, the controller obtains the electric angular velocity of the outer rotor in the first PWM cycle based on the third target voltage, the first target current, and the second target current. Wherein, the second PWM cycle is the next PWM cycle after the first PWM cycle, and the third target voltage is one or both of the first target voltage and the second target voltage; In some embodiments, the third voltage can be a first target voltage, that is, the controller obtains the electric angular velocity of the outer rotor in the first PWM cycle based on the first target voltage, the first target current and the second target current in the second PWM cycle.

[0079] In other embodiments, the third voltage can be a second target voltage, that is, the controller obtains the electric angular velocity of the outer rotor in the first PWM cycle based on the second target voltage, the first target current and the second target current in the second PWM cycle.

[0080] In other embodiments, the third voltage can be a first target voltage and a second target voltage. That is, the controller obtains the electric angular velocity of the outer rotor in the first PWM cycle based on the first target voltage, the second target voltage, the first target current and the second target current in the second PWM cycle.

[0081] In some embodiments, the controller uses a third target voltage, a first target current, and a second target current, combined with a motor mathematical model or related algorithms, such as estimation methods based on the relationship between voltage, current, and speed (without specific limitations), to deduce the electrical angular velocity of the external rotor motor 24 in the first PWM cycle. This calculation provides crucial speed feedback information for obtaining the second rotor position of the external rotor motor 24, and is an important step in achieving precise dynamic control of the external rotor motor 24.

[0082] Step S105: The controller obtains the second rotor angle corresponding to the second PWM cycle based on the electric angular velocity of the first PWM cycle, the first rotor angle, and the PWM cycle. In some embodiments, the controller uses the electrical angular velocity calculated in the first PWM cycle, the first rotor angle at the end of the first PWM cycle, and the known PWM cycle (i.e., the pulse width modulation time interval) to calculate the second rotor angle corresponding to the second PWM cycle through the instantaneous angle calculation logic of the rotating object at different times under a constant angular velocity. This update provides an accurate rotor position reference for subsequent SVPWM modulation, allowing the controller to obtain the second and third phase PWM duty cycles of the second PWM cycle without performing a complete FOC calculation. This solves the noise problem of the external rotor motor 24 during operation while saving computational resources.

[0083] Step S106: The controller performs space vector pulse width modulation based on the second rotor angle, the first target voltage, and the second target voltage to obtain the second three-phase PWM duty cycle.

[0084] In this embodiment, the controller first obtains the second rotor angle, the first target voltage, and the second target voltage. Then, based on these parameters, it executes the SVPWM algorithm to convert the first target voltage and the second target voltage into the second three-phase PWM duty cycle of the three-phase output signal corresponding to the first PWM cycle. This duty cycle is then used to turn the inverter switching transistors of the controller on and off, thereby enabling precise adjustment of the stator winding voltage of the external rotor motor 24.

[0085] For example, please refer to Figure 4 , Figure 4 This is a waveform diagram illustrating an SVPWM update strategy provided in an embodiment of this application, wherein... Figure 4Figure (1) is a waveform diagram of SVPWM updated once every two PWM cycles in related technologies, and Figure (2) is a waveform diagram of SVPWM updated twice every two cycles provided in the embodiment of this application. The figures include dead time, foc operation, start sampling, and SVPWM. Among them, dead time is a time gap between the upper and lower transistor drive waveforms of the same bridge arm of the air conditioner inverter, where both upper and lower transistors are in a turned-off state, to prevent the power devices in the inverter from being burned out due to shoot-through short circuit. foc operation refers to performing a complete FOC operation within this PWM cycle. It can be understood that a complete FOC calculation will also output the three-phase PWM duty cycle. Start sampling refers to sampling the three-phase current at this time node. SVPWM refers to not performing a complete FOC operation within this cycle, but outputting the three-phase PWM duty cycle. Therefore, from Figure 4 As can be seen from (1), a complete FOC operation is performed every two PWM cycles, and SVPWM is output. From Figure 4 As can be seen in (2), in this embodiment, a complete FOC calculation is performed in the first cycle, and SVPWM is output. In the second cycle, no complete FOC calculation is performed, and only SVPWM is output. In this embodiment, when the three-phase PWM duty cycle is updated in the second cycle, since the electrical angular velocity and voltage remain essentially unchanged for a very short time, the second rotor angle of the second cycle can be obtained based on the electrical angular velocity. The second three-phase PWM duty cycle of the second cycle can then be obtained based on the second rotor angle, the first target voltage, and the second target voltage, thereby greatly reducing the consumption of computational resources. Therefore, this solution can solve the problem of external motor noise with less computation.

[0086] For example, this application uses a PWM signal carrier frequency of 16kHz and an update frequency of 16kHz for the three-phase PWM duty cycle, which is updated once per PWM cycle. Please refer to [link to relevant documentation]. Figure 5 , Figure 5 This is a schematic diagram illustrating the fitting of a voltage vector to a vector circle within a circle, as provided in an embodiment of this application. Figure 5The diagram includes a first angle 51, a second angle 52, a first side 53, and a second side 54. The first angle 51 and the first side 53 represent the angle of each update of the fitted vector circle when the PWM signal carrier frequency is 16kHz and the three-phase PWM duty cycle is updated every two cycles, i.e., the voltage vector update frequency is 8kHz. The second angle 52 and the second side 54 represent the angle of each update of the voltage vector of the fitted vector circle when the PWM signal carrier frequency is 16kHz and the voltage vector update frequency is 16kHz. It can be seen that the size of the first angle 51 is twice the size of the second angle 52. Within the same size range of the first angle 51, there is only one first side 53, but there are two second sides 54. It can be understood that the circle fitted by the voltage vector of the size of the first angle 51 is not as smooth as the circle fitted by the size of the second angle 52. Furthermore, the circle fitted by the voltage vector at the first angle 51 has only half the number of sides of the circle fitted by the voltage vector at the second angle 52. That is, compared to the case where the PWM signal carrier frequency is 16kHz and the three-phase PWM duty cycle is updated every two cycles, i.e. the voltage vector update frequency is 8kHz, the control accuracy of the external rotor motor with an update frequency of 16kHz in this application is doubled.

[0087] In some embodiments, the external rotor motor 24 further includes a permanent magnet. In this application embodiment, the permanent magnet is a material that can maintain its magnetism for a long time without external magnetic field or current excitation.

[0088] Optionally, the permanent magnet can be a ferrite permanent magnet or a neodymium iron boron permanent magnet, etc. There are no specific restrictions here, and the choice can be made according to the actual situation.

[0089] exist Figure 3 In step S104, during the second PWM cycle, the controller obtains the electric angular velocity of the outer rotor during the first PWM cycle based on the third target voltage, the first target current, and the second target current. The controller can be configured to obtain target parameters, including the flux linkage of the permanent magnet, the stator resistance, the first inductance of the d-axis of the two-phase rotating coordinate system, and the second inductance of the q-axis of the two-phase rotating coordinate system. Based on the voltage equation of the outer rotor motor 24, the controller obtains the logical relationship between the electric angular velocity and the third target voltage, the first target current, the second target current, and the target parameters. The controller then obtains the electric angular velocity based on the logical relationship.

[0090] For a clearer understanding of this step, please refer to [link / reference]. Figure 6 , Figure 6 This is a flowchart of another controller control method disclosed in an embodiment of this application, which includes at least steps S201-S208.

[0091] Step S201: The controller acquires the three-phase current of the rotor motor 24 and the first rotor angle during the first pulse width modulation (PWM) cycle; Step S202: The controller performs field-oriented control (FOC) calculation based on the three-phase current and the first rotor angle to obtain the first target voltage and the first target current of the two-phase rotating coordinate system d-axis, and the second target voltage and the second target current of the two-phase rotating coordinate system q-axis. The d-axis is along the rotor flux linkage direction, and the q-axis is perpendicular to the d-axis. Step S203: The controller performs space vector pulse width modulation based on the first target voltage, the second target voltage, and the first rotor angle to obtain the first three-phase PWM duty cycle corresponding to the first PWM cycle; In this embodiment, the description of steps 201-203 is the same as the detailed description of steps 101-103 in the above embodiments, and will not be repeated in detail.

[0092] Step S204: During the second cycle, the controller acquires the target parameters, which include the magnetic flux of the permanent magnet, the stator resistance, the first inductance of the d-axis of the two-phase rotating coordinate system, and the second inductance of the q-axis of the two-phase rotating coordinate system. In some embodiments, the controller can acquire parameters such as permanent magnet flux linkage, stator resistance, first inductance of the d-axis and second inductance of the q-axis offline. This acquisition method involves pre-storing these target parameters in the controller's memory during the production of the external rotor motor 24 or the debugging phase of the controller, and then directly calling them during runtime.

[0093] In other embodiments, the controller can acquire parameters such as permanent magnet flux linkage, stator resistance, first inductance along the d-axis, and second inductance along the q-axis by real-time identification during operation.

[0094] For example, to obtain the stator resistance, a short-term DC current can be injected into the stator windings before starting the external rotor motor 24 or during low-speed operation. The controller collects the voltage and current signals at this time and calculates the real-time stator resistance according to Ohm's law. To obtain the first inductance of the d-axis or the second inductance of the q-axis, a high-frequency small-amplitude disturbance signal can be injected and calculated through impedance analysis, or it can be estimated using algorithms such as the extended Kalman filter in conjunction with the motor's dynamic voltage equation. To obtain the permanent magnet flux linkage, it can be obtained by inverse solving the q-axis dynamic voltage equation under load, based on the back electromotive force characteristics. It is understood that the above descriptions are only examples and no specific limitations are imposed here.

[0095] Step S205: Based on the voltage equation of the external rotor motor 24, obtain the logical relationship between the electric angular velocity and the third target voltage, the first target current, the second target current, and the target parameters; Step S206: Obtain the electric angular velocity according to the logical relationship.

[0096] The second PWM cycle is the next PWM cycle after the first PWM cycle, and the third target voltage is one or both of the first target voltage and the second target voltage.

[0097] In some embodiments, the third voltage can be the first target voltage, that is, the controller obtains the logical relationship between the electric angular velocity and the first target voltage, the first target current, the second target current and the target parameters according to the voltage equation of the external rotor motor 24.

[0098] In other embodiments, the third voltage can be a second target voltage, that is, the controller obtains the logical relationship between the electric angular velocity and the second target voltage, the first target current, the second target current and the target parameters according to the voltage equation of the external rotor motor 24.

[0099] In other embodiments, the third voltage can be a first target voltage and a second target voltage. That is, the controller obtains the logical relationship between the electric angular velocity and the first target voltage, the second target voltage, the first target current, the second target current, and the target parameters based on the voltage equation of the external rotor motor 24.

[0100] In this embodiment, the voltage equation of the external rotor motor 24 is used as the theoretical basis. The third target voltage, the first target current, the second target current, and the target parameters are substituted into the equation. A clear logical relationship between the electric angular velocity and these variables is established through mathematical derivation. That is, the expression of the electric angular velocity with respect to other parameters is derived from the voltage equation. Then, in step S206, the values ​​of the third target voltage, the first target current, the second target current, and the target parameters obtained by actual acquisition or calculation are substituted into the above logical relationship. The electric angular velocity of the current external rotor motor 24 can be directly solved, providing a key feedback basis for the subsequent second rotor angle update.

[0101] Step S207: The controller obtains the second rotor angle corresponding to the second PWM cycle based on the electrical angular velocity of the first PWM cycle, the first rotor angle, and the PWM cycle. Step S208: The controller performs space vector pulse width modulation based on the second rotor angle, the first target voltage, and the second target voltage to obtain the second three-phase PWM duty cycle.

[0102] In this embodiment, the description of steps 207-208 is the same as the detailed description of steps 105-106 in the above embodiments, and will not be repeated here.

[0103] In this scheme, the controller first acquires key target parameters of the motor, including permanent magnet flux linkage, stator resistance, and the first inductance along the d-axis and the second inductance along the q-axis in a two-phase rotating coordinate system. Then, based on the voltage equation of the external rotor motor 24, it establishes a logical relationship between the electric angular velocity and the third target voltage, the first target current, the second target current, and the aforementioned target parameters. Finally, the electric angular velocity is calculated based on this logical relationship. This method constructs the logical relationship based on the motor voltage equation, an essential model reflecting electromagnetic relationships, ensuring the theoretical accuracy of the electric angular velocity calculation. It can provide a reliable basis for the precise speed regulation and torque control of the external rotor motor 24.

[0104] exist Figure 3 In step S105: The controller obtains the second rotor angle corresponding to the second PWM cycle based on the electrical angular velocity of the first PWM cycle, the first rotor angle, and the PWM cycle; the controller can be configured to: obtain the product of the electrical angular velocity and the PWM cycle, obtain the sum of the product and the first rotor angle, and the sum is the second rotor angle.

[0105] For a clearer understanding of this step, please refer to [link / reference]. Figure 7 , Figure 7 This is a flowchart of another controller control method disclosed in an embodiment of this application, which includes at least steps S301-S307.

[0106] Step S301: The controller acquires the three-phase current of the rotor motor 24 and the first rotor angle during the first pulse width modulation (PWM) cycle; Step S302: The controller performs field-oriented control (FOC) calculation based on the three-phase current and the first rotor angle to obtain the first target voltage and the first target current of the two-phase rotating coordinate system d-axis, and the second target voltage and the second target current of the two-phase rotating coordinate system q-axis. The d-axis is along the rotor flux linkage direction, and the q-axis is perpendicular to the d-axis. Step S303: The controller performs space vector pulse width modulation based on the first target voltage, the second target voltage, and the first rotor angle to obtain the first three-phase PWM duty cycle corresponding to the first PWM cycle; Step S304: In the second PWM cycle, the controller obtains the electrical angular velocity of the outer rotor in the first PWM cycle based on the third target voltage, the first target current, and the second target current. Wherein, the second PWM cycle is the next PWM cycle after the first PWM cycle, and the third target voltage is one or both of the first target voltage and the second target voltage; In this embodiment, the description of steps 301-304 is the same as the detailed description of steps 101-104 in the above embodiments, and will not be repeated in detail.

[0107] Step S305: The controller obtains the product of the electrical angular velocity and the PWM period; Step S306: The controller obtains the sum of the product and the first rotor angle, and the sum is the second rotor angle.

[0108] The PWM period refers to a complete pulse cycle, that is, the total time from the "start of high level" to the "next start of high level," typically measured in seconds, milliseconds, or microseconds. For example, at a carrier frequency of 16kHz, if the PWM signal completes one high-to-low and low-to-high cycle every 0.0000625 seconds, its PWM period is 62.5 microseconds. It should be understood that this description of the PWM period size is merely an example and does not constitute a specific limitation.

[0109] Step S307: The controller performs space vector pulse width modulation based on the second rotor angle, the first target voltage and the second target voltage to obtain the second three-phase PWM duty cycle.

[0110] In this embodiment, the description of step 307 is the same as the detailed description of step 106 in the above embodiments, and will not be repeated in detail.

[0111] In this scheme, the controller obtains the product of the electrical angular velocity and the PWM period, then adds this product to the first rotor angle, and the sum is the second rotor angle, thus realizing the calculation and update of the rotor angle. This method can efficiently complete the second rotor angle update for the next PWM cycle based on one PWM cycle, thereby obtaining the second three-phase PWM duty cycle for the next cycle without performing complex FOC calculations. This reduces the computational load and also achieves the acquisition of the three-phase duty cycle signal in each PWM cycle to update the PWM signal, thus solving the noise problem.

[0112] exist Figure 3 In step S106: The controller performs space vector pulse width modulation based on the second rotor angle, the first target voltage, and the second target voltage to obtain the second three-phase PWM duty cycle. The controller can be configured to perform inverse Park transformation on the first target voltage and the second target voltage based on the second rotor angle to obtain the first voltage on the α axis of the two-phase stationary coordinate system and the second voltage on the β axis of the two-phase stationary coordinate system; obtain the amplitude and angle of the first space voltage vector based on the first voltage and the second voltage; and obtain the second three-phase PWM duty cycle based on the amplitude and angle of the first space voltage vector.

[0113] For a clearer understanding of this step, please refer to [link / reference]. Figure 8 , Figure 8This is a flowchart of another controller control method disclosed in an embodiment of this application, which includes at least steps S401-S407.

[0114] Step S401: The controller acquires the three-phase current of the rotor motor 24 and the first rotor angle during the first pulse width modulation (PWM) cycle; Step S402: The controller performs field-oriented control (FOC) calculation based on the three-phase current and the first rotor angle to obtain the first target voltage and the first target current of the two-phase rotating coordinate system d-axis, and the second target voltage and the second target current of the two-phase rotating coordinate system q-axis. The d-axis is along the rotor flux linkage direction, and the q-axis is perpendicular to the d-axis. Step S403: The controller performs space vector pulse width modulation based on the first target voltage, the second target voltage, and the first rotor angle to obtain the first three-phase PWM duty cycle corresponding to the first PWM cycle; Step S404: In the second PWM cycle, the controller obtains the electric angular velocity of the outer rotor in the first PWM cycle based on the third target voltage, the first target current, and the second target current. Wherein, the second PWM cycle is the next PWM cycle after the first PWM cycle, and the third target voltage is one or both of the first target voltage and the second target voltage; Step S405: The controller obtains the second rotor angle corresponding to the second PWM cycle based on the electrical angular velocity of the first PWM cycle, the first rotor angle, and the PWM cycle. In this embodiment, the description of steps 401-405 is the same as the detailed description of steps 101-105 in the above embodiments, and will not be repeated in detail.

[0115] Step S406: The controller performs an inverse Park transformation on the first target voltage and the second target voltage according to the second rotor angle to obtain the first voltage on the α axis of the two-phase stationary coordinate system and the second voltage on the β axis of the two-phase stationary coordinate system. In this embodiment, the inverse Park transformation is based on the angular relationship between the rotating coordinate system and the stationary coordinate system, and the coordinate transformation of the vector is achieved through trigonometric function operations.

[0116] For example, given the second rotor angle θ2, the first target voltage U along the d-axis of the rotating coordinate system d The second target voltage U along the q-axis of the rotating coordinate system q The first voltage U along the α-axis of the two-phase stationary coordinate system can be obtained using the following inverse Park formula. α And the second voltage U along the β axis of the two-phase stationary coordinate system β .

[0117]

[0118] Step S407: The controller obtains the amplitude and angle of the first space voltage vector based on the first voltage and the second voltage; and obtains the duty cycle of the second three-phase PWM based on the amplitude and angle of the first space voltage vector.

[0119] In this embodiment, the controller calculates the amplitude and angle of the first spatial voltage vector synthesized from the first voltage and the second voltage. The amplitude of the first spatial voltage vector reflects the voltage intensity, and the angle of the first spatial voltage vector reflects the phase position of the voltage vector in the complex plane. Subsequently, based on these two parameters, the SVPWM algorithm is used to determine the sector where the first spatial voltage vector is located, the duration of action of adjacent basic vectors, and the zero vector allocation ratio. Finally, it is converted into the duty cycle of the second three-phase PWM, which is the on-time ratio of the switching transistors of the air conditioner inverter.

[0120] In this scheme, the first and second target voltages are first subjected to an inverse Park transformation based on the second rotor angle to obtain the first voltage along the α-axis and the second voltage along the β-axis of the two-phase stationary coordinate system. Then, the amplitude and angle of the first spatial voltage vector are determined based on these two voltages. Finally, the duty cycle of the second three-phase PWM is calculated based on the amplitude and angle of this spatial voltage vector. This method achieves precise coordinate system transformation through the inverse Park transformation and calculates the duty cycle using the amplitude and angle of the spatial voltage vector. This conforms to the theoretical logic of voltage vector modulation in motor control, accurately reflects the correspondence between the motor voltage demand and the spatial vector, provides an accurate basis for PWM signal generation, and has clear steps that are easy to implement in engineering.

[0121] exist Figure 3 Step S102: The controller performs field-oriented control (FOC) calculation based on the three-phase current and the first rotor angle to obtain the first target voltage and the first target current along the d-axis of the two-phase rotating coordinate system, and to obtain the second target voltage and the second target current along the q-axis of the two-phase rotating coordinate system. The controller can be configured to: perform Clark transformation on the three-phase current to obtain the first current along the α-axis of the two-phase stationary coordinate system and the second current along the β-axis of the two-phase stationary coordinate system; perform Park transformation on the first current, the second current, and the first rotor angle to obtain the first target current along the d-axis of the two-phase rotating coordinate system and the second target current along the q-axis of the two-phase rotating coordinate system; and process the first target current and the second target current through the current loop PI regulator to obtain the first target voltage and the second target voltage.

[0122] For a clearer understanding of this method, please refer to [link / reference]. Figure 9 , Figure 9This is a flowchart of another controller control method disclosed in an embodiment of this application, which includes at least steps S501-S508.

[0123] Step S501: The controller acquires the three-phase current of the rotor motor 24 and the first rotor angle during the first pulse width modulation (PWM) cycle. In this embodiment, the description of step 501 is the same as the detailed description of step 101 in the above embodiments, and will not be repeated in detail.

[0124] Step S502: The controller performs Clark transformation on the three-phase current to obtain the first current along the α axis of the two-phase stationary coordinate system and the second current along the β axis of the two-phase stationary coordinate system; In this embodiment, the Clark transformation converts the three-phase current in the three-phase coordinate system into the first and second currents in the two-phase stationary coordinate system through linear transformation. While retaining all the electromagnetic information of the motor, it reduces the number of control variables and eliminates the coupling between the three-phase variables.

[0125] For example, the three-phase currents in a three-phase stationary coordinate system are known to be I... a I b and I c The first current I along the α axis of the two-phase stationary coordinate system can be obtained using the following formula. α The second current I along the β axis of the two-phase stationary coordinate system β .

[0126]

[0127] Step S503: The controller performs Park transformation on the first current, the second current and the first rotor angle to obtain the first target current on the d-axis of the two-phase rotating coordinate system and the second target current on the q-axis of the two-phase rotating coordinate system; In this embodiment, the essence of the Park transformation is to achieve vector transformation through trigonometric function operations based on the angular relationship between the stationary coordinate system and the rotating coordinate system.

[0128] For example, the first current I along the α axis of a two-phase stationary coordinate system is known. α The second current I along the β axis of the two-phase stationary coordinate system β Given the first rotor angle θ1, the first target current I along the d-axis of the two-phase rotating coordinate system can be obtained using the following formula. d The second target current I along the q-axis of the two-phase rotating coordinate system q .

[0129]

[0130] Step S504: Process the first target current and the second target current through the current loop PI regulator to obtain the first target voltage and the second target voltage.

[0131] In some embodiments, the first target voltage is obtained by processing the first target current through a current loop PI regulator. This can be achieved by obtaining a first target error based on a first preset current and a first target current along the d-axis of a set two-phase rotating coordinate system; and by obtaining the first target voltage based on a proportional coefficient, an integral coefficient, and the first target error along the d-axis of a set two-phase rotating coordinate system. In other embodiments, the second target voltage is obtained by processing the second target current through a current loop PI regulator. This can be achieved by obtaining the second target error based on the second preset current and the second target current of the set two-phase rotating coordinate system q-axis; and by obtaining the second target voltage based on the set proportional coefficient of the set two-phase rotating coordinate system q-axis, the set integral coefficient of the set two-phase rotating coordinate system q-axis, and the second target error.

[0132] In this scheme, the first target error is obtained by calculating the difference between the first preset current and the first target current of the d-axis in a two-phase rotating coordinate system. This error is then processed using the proportional and integral coefficients set for the d-axis to obtain the first target voltage. Simultaneously, the second target error is obtained by calculating the difference between the second preset current and the second target current of the q-axis. This error is also processed using the proportional and integral coefficients set for the q-axis to obtain the second target voltage. This method employs a split-axis independent PI control strategy, where the d-axis and q-axis are adjusted according to the error between their respective preset currents and actual currents. This allows for targeted optimization of the control performance of each axis, ensuring independent control of the excitation and torque components. Furthermore, the flexible setting of proportional and integral coefficients quickly eliminates current errors, improving the accuracy and dynamic response of current control and meeting the control requirements of the motor under different operating conditions.

[0133] Step S505: The controller performs space vector pulse width modulation based on the first target voltage, the second target voltage, and the first rotor angle to obtain the first three-phase PWM duty cycle corresponding to the first PWM cycle; Step S506: In the second PWM cycle, the controller obtains the electrical angular velocity of the outer rotor in the first PWM cycle based on the third target voltage, the first target current, and the second target current. Wherein, the second PWM cycle is the next PWM cycle after the first PWM cycle, and the third target voltage is one or both of the first target voltage and the second target voltage; Step S507: The controller obtains the second rotor angle corresponding to the second PWM cycle based on the electrical angular velocity of the first PWM cycle, the first rotor angle, and the PWM cycle. Step S508: The controller performs space vector pulse width modulation based on the second rotor angle, the first target voltage, and the second target voltage to obtain the second three-phase PWM duty cycle.

[0134] In this embodiment, the description of steps 505-508 is the same as the detailed description of steps 103-106 in the above embodiments, and will not be repeated in detail.

[0135] In this scheme, the three-phase currents are first subjected to Clark transformation to obtain the first current along the α-axis and the second current along the β-axis in a two-phase stationary coordinate system. Then, combined with the first rotor angle, these two currents are subjected to Park transformation to obtain the first target current along the d-axis and the second target current along the q-axis in a two-phase rotating coordinate system. Finally, the two target currents are processed by a current loop PI regulator to output the first target voltage and the second target voltage. This method achieves accurate conversion from three-phase current to two-phase rotating coordinate system current through Clark and Park transformations, which conforms to the theoretical framework of motor vector control. Furthermore, the closed-loop control of the first and second target currents by the PI regulator provides a reliable voltage regulation basis for obtaining the PWM signal of the external rotor motor 24.

[0136] In some embodiments, the air conditioner further includes a sensor that can be connected to the external rotor motor 24 and is configured to acquire a first rotor angle; the sensor is also communicatively connected to a controller that is configured to acquire the first rotor angle through the sensor.

[0137] In this embodiment of the application, where the air conditioner also includes a sensor, please refer to... Figure 10 , Figure 10 This is a flowchart of another controller control method disclosed in an embodiment of this application, which includes at least steps S601-S609.

[0138] Step S601: The controller acquires the three-phase current of the rotor motor 24 inside and outside the first pulse width modulation (PWM) cycle and acquires the first rotor angle through the sensor; In some embodiments, the sensor is an encoder configured to acquire rotational position information of the rotor of the external rotor motor 24. Based on the fact that the air conditioner includes an encoder, the controller is configured to acquire rotational position information through the encoder, process the rotational position information, and acquire a first rotor angle.

[0139] In this scheme, the air conditioner uses an encoder as a sensor to acquire the rotational position information of the 24 rotors of the external rotor motor. The controller obtains and processes this rotational position information through the encoder to obtain the first rotor angle. This method uses an encoder as a high-precision position detection element, which can accurately acquire rotor rotational position information, providing high-quality raw data for calculating the first rotor angle and ensuring the accuracy of the angle information. Furthermore, the controller's processing of the position information can further optimize the angle result to meet the accuracy requirements of motor control. In addition, the encoder's real-time detection characteristics can promptly reflect changes in rotor position, providing a rapid response position basis for the dynamic control of the motor and improving overall control performance.

[0140] In other embodiments, the sensor is a rotary transformer configured to acquire the induced electromotive force when the stator and rotor of the external rotor motor 24 are in an electromagnetically coupled state; based on the fact that the air conditioner includes a rotary transformer, the controller is configured to acquire the induced electromotive force through the rotary transformer and process the induced electromotive force to acquire a first rotor angle.

[0141] In this scheme, a rotary transformer is used as the sensor to acquire the induced electromotive force (EMF) when the stator and rotor of the external rotor motor 24 are in an electromagnetic coupling state. The controller acquires and processes this induced EMF through the rotary transformer to obtain the first rotor angle. The rotary transformer has strong anti-interference capabilities and environmental adaptability, and can stably acquire the induced EMF even under harsh operating conditions, providing a reliable raw signal for calculating the first rotor angle. The rotor angle obtained by processing the induced EMF conforms to the physical characteristics of electromagnetic coupling, ensuring the accuracy of the angle information. Furthermore, the rotary transformer has a robust and durable structure, allowing for long-term stable operation, which helps improve the reliability and service life of the motor control system.

[0142] In other embodiments, the sensor is a Hall sensor, which is configured to convert magnetic field information of the rotor of the external rotor motor 24 in a rotating state into a discrete electrical signal; based on the fact that the air conditioner includes the Hall sensor, the controller is configured to: acquire the discrete electrical signal through the Hall sensor, process the discrete electrical signal, and acquire a first rotor angle.

[0143] In this scheme, Hall effect sensors are used, which convert the magnetic field information of the external rotor motor 24 during rotor rotation into discrete electrical signals. The controller acquires and processes these discrete electrical signals through the Hall effect sensors to obtain the first rotor angle. Hall effect sensors are simple in structure and low in cost, making them suitable for large-scale applications. Their ability to convert magnetic field information into discrete electrical signals simplifies signal processing and allows for rapid provision of rotor position information to the controller. Furthermore, the Hall effect sensors have a fast response speed, promptly reflecting the rotor rotation state and meeting the basic real-time requirements of motor control.

[0144] It is understood that the above description of the sensor acquiring the first rotor angle is merely an example, but not limited to it.

[0145] Step S602: Perform Clark transformation on the three-phase currents to obtain the first current along the α axis of the two-phase stationary coordinate system and the second current along the β axis of the two-phase stationary coordinate system.

[0146] Step S603: Perform Park transformation on the first current, the second current, and the first rotor angle to obtain the first target current on the d-axis of the two-phase rotating coordinate system and the second target current on the q-axis of the two-phase rotating coordinate system.

[0147] Step S604: Process the first target current and the second target current through the current loop PI regulator to obtain the first target voltage and the second target voltage.

[0148] In this embodiment, the description of steps 602-604 is the same as the detailed description of steps 502-504 in the above embodiments, and will not be repeated in detail.

[0149] Step S605: During the second cycle, acquire the target parameters, which include the magnetic flux linkage of the permanent magnet, the stator resistance, the first inductance of the d-axis of the two-phase rotating coordinate system, and the second inductance of the q-axis of the two-phase rotating coordinate system.

[0150] Step S606: Based on the voltage equation of the external rotor motor 24, obtain the logical relationship between the electric angular velocity and the third target voltage, the first target current, the second target current, and the target parameters, and obtain the electric angular velocity based on the logical relationship.

[0151] In this embodiment, the description of steps 605-606 is the same as the detailed description of steps 204-206 in the above embodiments, and will not be repeated in detail.

[0152] Step S607: Obtain the product of the electrical angular velocity and the PWM period, obtain the sum of the product and the first rotor angle, and the sum is the second rotor angle.

[0153] In this embodiment, the description of step 607 is the same as that of steps 305-306 in the above embodiments, and will not be repeated in detail.

[0154] Step 608: The controller performs an inverse Park transformation on the first target voltage and the second target voltage according to the second rotor angle to obtain the first voltage on the α axis of the two-phase stationary coordinate system and the second voltage on the β axis of the two-phase stationary coordinate system.

[0155] Step 609: The controller obtains the amplitude and angle of the first spatial voltage vector based on the first voltage and the second voltage; and obtains the duty cycle of the second three-phase PWM based on the amplitude and angle of the first spatial voltage vector.

[0156] In this embodiment, the description of steps 608-609 is the same as the detailed description of steps 406-407 in the above embodiments, and will not be repeated in detail.

[0157] Based on the control method of the controller described above, this application also discloses a computer-readable storage medium that can implement any of the above control methods.

[0158] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a non-volatile computer-readable storage medium. When executed, the program can include the processes of the embodiments of the methods described above. The storage medium can be a magnetic disk, optical disk, ROM, etc.

[0159] It should be understood that the phrase "one embodiment" or "an embodiment" throughout the specification means that a specific feature, structure, or characteristic related to the embodiment is included in at least one embodiment of this application. Therefore, "in one embodiment" or "in an embodiment" appearing throughout the specification does not necessarily refer to the same embodiment. Furthermore, these specific features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Those skilled in the art should also recognize that the embodiments described in the specification are optional embodiments, and the actions and modules involved are not necessarily essential to this application.

[0160] In the various embodiments of this application, it should be understood that the sequence number of each process does not necessarily imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0161] The air conditioner disclosed in the embodiments of this application has been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this application. At the same time, those skilled in the art will recognize that there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. An air conditioner, characterized in that, The air conditioner includes: compressor; An indoor heat exchanger, connected to the compressor, is configured to exchange heat with indoor air via refrigerant; An outdoor heat exchanger, connected to the compressor, is configured to exchange heat with outdoor air via the refrigerant; The four-way valve includes a first port, a second port, a third port, and a fourth port. The first port is connected to the air outlet of the compressor, the second port is connected to the air inlet of the compressor, the third port is connected to the indoor heat exchanger, and the fourth port is connected to the outdoor heat exchanger. An indoor fan includes an external rotor motor, the stator of which is located inside the external rotor motor and the rotor of which is located outside the external rotor motor, and is configured to rotate under the drive of the external rotor motor to deliver indoor air to the air conditioner after passing through the indoor heat exchanger. The controller, electrically connected to both the compressor and the four-way valve, is configured to control the direction of the four-way valve to adjust the flow of the refrigerant. The controller is configured as follows: Obtain the three-phase current and the first rotor angle of the external rotor motor during the first pulse width modulation (PWM) cycle; Based on the three-phase current and the first rotor angle, field-oriented control (FOC) calculation is performed to obtain the first target voltage and the first target current along the d-axis of the two-phase rotating coordinate system, and to obtain the second target voltage and the second target current along the q-axis of the two-phase rotating coordinate system, wherein the d-axis is along the magnetic flux direction of the rotor and the q-axis is perpendicular to the d-axis; Based on the first target voltage, the second target voltage, and the first rotor angle, space vector pulse width modulation is performed to obtain the first three-phase PWM duty cycle corresponding to the first PWM cycle; In the second PWM cycle, the electric angular velocity of the outer rotor in the first PWM cycle is obtained based on the third target voltage, the first target current and the second target current. The second PWM cycle is the next PWM cycle after the first PWM cycle. The third target voltage is one or both of the first target voltage and the second target voltage. Based on the electrical angular velocity of the first PWM cycle, the first rotor angle, and the PWM cycle, the second rotor angle corresponding to the second PWM cycle is obtained; Space vector pulse width modulation is performed based on the second rotor angle, the first target voltage, and the second target voltage to obtain the second three-phase PWM duty cycle.

2. The air conditioner according to claim 1, characterized in that, The external rotor motor also includes a permanent magnet, and the controller is configured to: Obtain target parameters, including the magnetic flux linkage of the permanent magnet, the stator resistance, the first inductance of the d-axis of the two-phase rotating coordinate system, and the second inductance of the q-axis of the two-phase rotating coordinate system; Based on the voltage equation of the external rotor motor, obtain the logical relationship between the electric angular velocity and the third target voltage, the first target current, the second target current, and the target parameters; The electric angular velocity is obtained based on the logical relationship described above.

3. The air conditioner according to claim 1, characterized in that, The controller is configured to: Obtain the product of the electrical angular velocity and the PWM period; Obtain the sum of the product and the first rotor angle, where the sum is the second rotor angle.

4. The air conditioner according to claim 1, characterized in that, The controller is configured to: Based on the second rotor angle, perform an inverse Park transformation on the first target voltage and the second target voltage to obtain the first voltage along the α axis of the two-phase stationary coordinate system and the second voltage along the β axis of the two-phase stationary coordinate system. The magnitude and angle of the first spatial voltage vector are obtained based on the first voltage and the second voltage. The duty cycle of the second three-phase PWM is obtained based on the magnitude and angle of the first space voltage vector.

5. The air conditioner according to claim 1, characterized in that, The controller is configured to: Perform Clark transformation on the three-phase currents to obtain the first current along the α-axis of the two-phase stationary coordinate system and the second current along the β-axis of the two-phase stationary coordinate system. The first current, the second current, and the first rotor angle are subjected to Park transformation to obtain the first target current on the d-axis of the two-phase rotating coordinate system and the second target current on the q-axis of the two-phase rotating coordinate system. The first target current and the second target current are processed by a current loop PI regulator to obtain the first target voltage and the second target voltage.

6. The air conditioner according to claim 5, characterized in that, The controller is configured to: The first target error is obtained based on the first preset current of the d-axis of the set two-phase rotating coordinate system and the first target current. The first target voltage is obtained based on the set scaling factor of the d-axis of the two-phase rotating coordinate system, the set integral factor of the d-axis of the two-phase rotating coordinate system, and the first target error; and, The second target error is obtained based on the second preset current of the q-axis of the set two-phase rotating coordinate system and the second target current. The second target voltage is obtained based on the set scaling factor of the q-axis of the two-phase rotating coordinate system, the set integral factor of the q-axis of the two-phase rotating coordinate system, and the second target error.

7. The air conditioner according to claim 1, characterized in that, The air conditioner also includes sensors. The sensor, connected to the external rotor motor, is configured to acquire the first rotor angle; The sensor is also communicatively connected to the controller, which is configured to: The first rotor angle is obtained through the sensor.

8. The air conditioner according to claim 7, characterized in that, The sensor is an encoder. The encoder is configured to acquire the rotational position information of the rotor of the external rotor motor. The controller is configured to: The encoder is used to obtain the rotational position information, and the rotational position information is processed to obtain the first rotor angle.

9. The air conditioner according to claim 7, characterized in that, The sensor is a rotary transformer. The rotary transformer is configured to obtain the induced electromotive force of the stator and rotor of the external rotor motor when they are in an electromagnetic coupling state. The controller is configured to: The induced electromotive force is obtained through the rotary transformer, and the induced electromotive force is processed to obtain the first rotor angle.

10. The air conditioner according to claim 7, characterized in that, The sensor is a Hall sensor. The Hall sensor is configured to convert the magnetic field information of the external rotor motor when the rotor is rotating into a discrete electrical signal. The controller is configured to: The discrete electrical signal is acquired through the Hall sensor, and the discrete electrical signal is processed to obtain the first rotor angle.

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