Air conditioner

Abstract

The invention provides an air conditioner. The air conditioner comprises a compressor; the controller is electrically connected with the compressor, and the controller is configured to obtain the running frequency range and the driving frequency of the compressor; according to the preset boundary frequency, the operation frequency range of the compressor is divided into at least two frequency bands, each frequency band corresponds to one Vdc control upper limit value, and the Vdc control upper limit value corresponding to the low frequency band is smaller than the Vdc control upper limit value corresponding to the high frequency band; according to the preset boundary frequency and the driving frequency, the current frequency band of the compressor is judged, and the current corresponding Vdc control upper limit value of the compressor is determined; wherein the Vdc control upper limit value is the upper limit value of the Vdc given value; and outputting the direct-current bus voltage Vdc to a compressor to drive the compressor to operate. According to the method, the operation frequency range of the compressor is segmented, the compressor is controlled by using different Vdc control upper limit values in different segmented intervals, and the high-frequency operation requirement of the compressor and the service life of the electrolytic capacitor are both considered.

Description

Technical Field

[0001] The invention belongs to the technical field of air conditioning, and in particular relates to an air conditioner. Background Art

[0002] The air conditioner includes an indoor unit and an outdoor unit. The compressor of the outdoor unit of the current air conditioner in the industry generally uses a permanent magnet synchronous motor. As the speed of the permanent magnet synchronous motor gradually increases, the back electromotive force also gradually increases, and compared with the resistance voltage drop, the proportion gradually increases (ignoring the inductance voltage drop caused by the current change). When the speed rises to a certain value, the speed cannot continue to rise due to the limitation of the voltage limit ellipse. At this time, if you want to continue to increase the speed, you can only increase the DC bus voltage at the input end of the power module. However, the upper limit of the DC bus voltage is limited, resulting in the compressor The high frequency of the permanent magnet synchronous motor also has an upper limit, and the more pole pairs the compressor has, the lower the upper frequency limit. At the same time, increasing the DC bus voltage will cause the electrolytic capacitor in the PFC circuit to work in a high voltage state for a long time, which will shorten its life. In view of this, this application is proposed. Summary of the invention

[0003] The present invention provides an air conditioner, which controls the compressor by segmenting the operating frequency range of the compressor and using different Vdc control upper limit values ​​in different segmented intervals, so that when the driving frequency to be operated is relatively high, the Vdc control upper limit value can be set relatively high, and when the driving frequency to be operated is relatively low, the Vdc control upper limit value uses a lower setting value, thereby taking into account the high-frequency operation requirements of the compressor and the service life of the electrolytic capacitor, and effectively solving the above-mentioned technical problems.

[0004] To this end, the present application provides an air conditioner, which includes:

[0005] The refrigerant circulation loop allows the refrigerant to circulate in the loop consisting of the compressor, condenser, expansion valve, and evaporator;

[0006] A compressor, used for compressing the refrigerant gas in a low-temperature and low-pressure state into a refrigerant gas in a high-temperature and high-pressure state and discharging the refrigerant gas to a condenser, wherein the compressor comprises a permanent magnet synchronous motor;

[0007] A controller is electrically connected to at least the compressor, and the controller is configured to:

[0008] Obtaining an operating frequency range and a driving frequency of the compressor;

[0009] According to a preset dividing frequency, the operating frequency range of the compressor is divided into at least two frequency segments, each of the frequency segments corresponds to a Vdc control upper limit value, and the Vdc control upper limit value corresponding to the frequency segment with a low operating frequency is smaller than the Vdc control upper limit value corresponding to the frequency segment with a high operating frequency;

[0010] According to the preset boundary frequency and the driving frequency, the frequency segment in which the compressor is currently located is judged, and according to the corresponding relationship between the frequency segment and the Vdc control upper limit value, the Vdc control upper limit value corresponding to the compressor is determined, and the Vdc control upper limit value is the upper limit value of the Vdc given value;

[0011] The DC bus voltage Vdc is output to the compressor to drive the compressor to operate, and a modulation ratio is obtained. When the modulation ratio meets a preset condition, the DC bus voltage Vdc is the Vdc given value.

[0012] In some embodiments of the present application, the controller is configured to:

[0013] Get indoor ambient temperature, set temperature, and outdoor ambient temperature;

[0014] Determine the target frequency of the compressor according to the indoor ambient temperature, the set temperature, and the outdoor ambient temperature;

[0015] The driving frequency F_dri is determined based on the target frequency and after the air conditioning system is protected by frequency reduction or frequency increase prohibition.

[0016] In some embodiments of the present application, the operating frequency range of the compressor is determined according to the temperature range of the outdoor ambient temperature, wherein the operating frequency range of the compressor includes the maximum allowable operating frequency of the compressor and the minimum allowable operating frequency of the compressor.

[0017] In some embodiments of the present application, the preset dividing frequency includes a dividing frequency F_divide, and the dividing frequency F_divide is less than the maximum allowable operating frequency of the compressor and greater than the minimum allowable operating frequency of the compressor, so as to divide the operating frequency range of the compressor into two frequency bands; wherein, the value above the dividing frequency F_divide is the Vdc control high frequency band, and the value below the dividing frequency F_divide is the Vdc control low frequency band.

[0018] In some embodiments of the present application, the controller is powered by an AC power supply, and when the AC power supply provides low voltage electricity, the Vdc control upper limit value is Vdc_limit;

[0019] If the driving frequency F_dri is in the Vdc control low frequency band, the corresponding Vdc_limit is a preset constant value Vdc_limit_low; if the driving frequency F_dri is in the Vdc control high frequency band, the corresponding Vdc_limit is a preset constant value Vdc_limit_high, wherein Vdc_limit_high>Vdc_limit_low.

[0020] In some embodiments of the present application, the controller is powered by an AC power supply, and when the AC power supply provides low voltage electricity, the Vdc control upper limit value is Vdc_limit;

[0021] If the driving frequency F_dri is in the Vdc control low frequency band, the corresponding Vdc_limit is a preset constant value Vdc_limit_low;

[0022] Take the function f(F_dri) of the driving frequency. If the driving frequency F_dri is in the Vdc control high frequency band, the corresponding Vdc_limit is calculated according to the first logic: Vdc_limit=Vdc_limit_delta*sat(F_dri)+Vdc_limit_low;

[0023] Among them, Vdc_limit_delta is the maximum bias value of the Vdc control upper limit in the high frequency band, and sat(F_dri) is the saturation function.

[0024] In some embodiments of the present application, the saturation function sat(F_dri) is obtained according to a second logical operation, wherein the second logical operation is:

[0025]

[0026] Wherein, sat(F_dri) takes the positive part of the horizontal axis frequency, k=1 / deltaF, and deltaF is a preset frequency value belonging to the high frequency band of Vdc control.

[0027] In some embodiments of the present application, when the AC power supply provides high voltage electricity, the Vdc control upper limit value corresponding to the Vdc control low frequency band and the Vdc control high frequency band is Vdc_limit_hiVol; when the AC power supply provides low voltage electricity, the Vdc control upper limit value corresponding to the Vdc control low frequency band and the Vdc control high frequency band is Vdc_limit, and Vdc_limit_hiVol is superimposed with a lift voltage deltaV relative to Vdc_limit.

[0028] In some embodiments of the present application, the controller includes:

[0029] A rectifier and filter circuit having an electrical interface connected to an AC power source;

[0030] A power module, an output end of which is electrically connected to the compressor to drive the compressor to operate;

[0031] A PFC circuit, wherein an input end thereof is electrically connected to an output end of the rectifier and filter circuit, and an output end of the PFC circuit is electrically connected to an input end of the power module via a DC bus, so that the PFC circuit outputs the DC bus voltage to the power module;

[0032] A control module is electrically connected to the PFC circuit and the power module.

[0033] In some embodiments of the present application, the control module calculates and determines the Vdc given value corresponding to the DC bus voltage Vdc based on the modulation ratio; when the modulation ratio is higher than the preset ratio M, at this time, the DC bus voltage Vdc is the same as the Vdc given value, and the DC bus voltage Vdc is calculated based on the maximum voltage controlled by the PFC circuit and the output voltage of the rectifier and filter circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0035] Figure 1 is a schematic diagram of the three-dimensional structure of an air conditioner according to an embodiment of the present disclosure;

[0036] Figure 2 is a system block diagram of an air conditioner according to an embodiment of the present disclosure;

[0037] Figure 3 is a system block diagram of an air conditioner outdoor unit according to an embodiment of the present disclosure;

[0038] Figure 4 is a system block diagram of another air-conditioning outdoor unit according to an embodiment of the present disclosure;

[0039] Figure 5 is a system block diagram of another air conditioner outdoor unit according to an embodiment of the present disclosure;

[0040] Figure 6 is a schematic structural diagram of a refrigerant circulation circuit according to an embodiment of the present disclosure;

[0041] Figure 7 is a schematic diagram of the circuit structure of an air conditioner according to an embodiment of the present disclosure;

[0042] Figure 8 is a structural block diagram of a controller according to an embodiment of the present disclosure;

[0043] Fig. 9is a system block diagram of another air conditioner according to an embodiment of the present disclosure;

[0044] Fig.10 is a schematic diagram of the hardware structure of an outdoor control device according to an embodiment of the present disclosure;

[0045] Fig.11 is a control logic diagram of the operation of the compressor according to an embodiment of the present disclosure;

[0046] Fig.12 is a flow chart for calculating the driving frequency and the operating frequency range according to an embodiment of the present disclosure;

[0047] Fig.13 is a flow chart for determining the frequency band in which the compressor is currently located according to an embodiment of the present disclosure;

[0048] Fig.14 is a flow chart for determining Vdc_limit according to a frequency band according to an embodiment of the present disclosure;

[0049] Fig.15 is a flow chart of determining Vdc_limit according to a frequency band according to another embodiment of the present disclosure;

[0050] Fig.16 is a schematic diagram of calculating Vdc_limit as a function of driving frequency according to an embodiment of the present disclosure;

[0051] Fig.17 is the voltage limit ellipse of the permanent magnet synchronous motor according to an embodiment of the present disclosure.

[0052] In the above figures: air conditioner 100; air conditioner outdoor unit 1; air conditioner indoor unit 2; refrigerant circulation loop 3; compressor 31; permanent magnet synchronous motor 311; condenser 32; expansion valve 33; evaporator 34; four-way valve 35; controller 4; indoor control device 41; outdoor control device 42; rectifier filter circuit 421; PFC circuit 422; power module 423; control module 424; DC bus 425; indoor fan 5; outdoor fan 6; AC power supply 7. DETAILED DESCRIPTION

[0053] The present invention is described in detail below by way of exemplary embodiments. However, it should be understood that elements, structures, and features in one embodiment may also be beneficially combined in other embodiments without further description.

[0054] In the description of the present invention, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0055] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features.

[0056] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0057] refer to Figure 1 to Figure 17 , the present application embodiment provides an air conditioner 100. Referring to Figures 1-2 The air conditioner 100 includes an air conditioner indoor unit 2 and an air conditioner outdoor unit 1. The air conditioner indoor unit 2 is arranged indoors for exchanging heat with the indoor environment, and the air conditioner outdoor unit 1 is usually arranged outdoors for bringing indoor heat to the outdoors.

[0058] In this embodiment, Figure 1 As shown, the air conditioner indoor unit 2 can be an indoor hanging unit hung on a wall or other structure, and the air conditioner indoor unit 2 can be hung on the indoor wall, and the rear plate of the air conditioner indoor unit 2 is against the wall. For another example, an indoor cabinet (not shown in the figure) is also a form of the air conditioner indoor unit 2. When the air conditioner indoor unit 2 is an indoor cabinet, the indoor cabinet can be cylindrical, square, irregular, or the like.

[0059] The air conditioner indoor unit 2 includes a casing, which forms the appearance of the air conditioner indoor unit 2. An air inlet and an air outlet are formed on the casing, and a heat exchange air duct is formed inside the casing. The heat exchange air duct is connected with the air inlet so that indoor air enters the heat exchange air duct from the air inlet, and the heat exchange air duct is connected with the air outlet so that the conditioned air in the heat exchange air duct can flow into the room from the air outlet of the casing.

[0060] The air conditioner indoor unit 2 also includes an indoor heat exchanger and an indoor fan 5. The indoor heat exchanger is arranged in the heat exchange air duct and is used to perform heat exchange with the air in the heat exchange air duct entering the casing. The indoor fan 5 is arranged in the heat exchange air duct and is used to drive the indoor air outside the casing into the heat exchange air duct, and the indoor fan 5 drives the air in the heat exchange air duct to flow from the air inlet to the air outlet.

[0061] The air conditioner outdoor unit 1 includes a compressor 31, a four-way valve 35 and an outdoor heat exchanger, wherein the compressor 31 is used to compress the refrigerant gas in a low-temperature and low-pressure state into a refrigerant gas in a high-temperature and high-pressure state; the four-way valve is used to switch the flow path of the refrigerant; and the outdoor heat exchanger is used to perform heat exchange between the refrigerant and the outdoor air. Figure 4 As shown, the compressor 31 includes a permanent magnet synchronous motor 311 , and the permanent magnet synchronous motor 311 is configured as a power source of the compressor 31 .

[0062] The air conditioner 100 further includes an expansion valve 33 disposed in the air conditioner indoor unit 2 or the air conditioner outdoor unit 1 , and the expansion valve 33 is used for throttling in a cooling condition or a heating condition.

[0063] Specifically, the expansion valve 33 may include an electronic expansion valve and a thermal expansion valve, wherein the electronic expansion valve is provided in the air-conditioning outdoor unit 1, and the electronic expansion valve is used to throttle in the heating mode to control the refrigerant flow rate of the pipeline between the indoor heat exchanger and the outdoor heat exchanger in the heating mode. The thermal expansion valve is provided in the air-conditioning indoor unit 2, and the thermal expansion valve is used to throttle in the cooling mode to control the refrigerant flow rate of the pipeline between the indoor heat exchanger and the outdoor heat exchanger in the cooling mode.

[0064] The air conditioner 100 includes a refrigerant circulation circuit 3, and can perform a vapor compression refrigeration cycle by circulating a refrigerant in the refrigerant circulation circuit 3. The air conditioner indoor unit 2 and the air conditioner outdoor unit 1 are connected by connecting pipes to form the refrigerant circulation circuit 3 for circulating a refrigerant. The refrigerant is a refrigerant.

[0065] The outdoor unit of the air conditioner 100, namely the air conditioner outdoor unit 1, refers to a part of the refrigeration cycle including the compressor 31 and the outdoor heat exchanger, the indoor unit of the air conditioner 100, namely the air conditioner indoor unit 2, includes an indoor heat exchanger, and the expansion valve 33 can be provided in the indoor unit or the outdoor unit.

[0066] Reference Figure 7, the circuit structure of the air conditioner 100 is shown in the figure. In the present application, the air conditioner 100 performs the refrigeration cycle of the air conditioner 100 by using a loop composed of a compressor 31, a condenser 32, an expansion valve 33 and an evaporator 34. The refrigeration cycle includes a series of processes, involving compression, condensation, expansion and evaporation, and supplies refrigerant to the conditioned and heat-exchanged air. The high-pressure and low-pressure states required for the operation of the refrigerant are established by the compressor 31, and heat is exchanged with the outdoor air to release the heat of the indoor air to the outdoor air (cooling condition) or to supplement the heat absorbed from the outdoor air to the indoor air (heating condition).

[0067] Compression process: The compressor 31 compresses the refrigerant gas in a low-temperature and low-pressure state into a refrigerant gas in a high-temperature and high-pressure state and discharges the compressed refrigerant gas. The compressor 31 may be a variable-capacity inverter compressor 31 that performs inverter-based speed control. The refrigerant gas discharged by the compressor 31 flows into the condenser 32.

[0068] Condensation process: The condenser 32 condenses the compressed refrigerant into a liquid phase, and heat is released to the surrounding environment through the condensation process.

[0069] Expansion process: The expansion valve 33 expands the high-temperature and high-pressure liquid-phase refrigerant condensed in the condenser 32 into a low-pressure liquid-phase refrigerant.

[0070] Evaporation process: The evaporator 34 evaporates the refrigerant expanded in the expansion valve 33 and returns the refrigerant gas in a low temperature and low pressure state to the compressor 31. The evaporator 34 can achieve a refrigeration effect by utilizing the latent heat of evaporation of the refrigerant to exchange heat with the material to be cooled. In the whole cycle, the air conditioner 100 can adjust the temperature of the indoor space.

[0071] The indoor heat exchanger and the outdoor heat exchanger function as the condenser 32 or the evaporator 34. When the indoor heat exchanger functions as the condenser 32, the air conditioner 100 functions as a heater in the heating mode, and when the indoor heat exchanger functions as the evaporator 34, the air conditioner 100 functions as a cooler in the cooling mode. That is, in the cooling mode, the indoor heat exchanger is the evaporator 34 and the outdoor heat exchanger is the condenser 32. In the heating mode, the indoor heat exchanger is the condenser and the outdoor heat exchanger is the evaporator 34.

[0072] The air conditioner outdoor unit 1 further includes an outdoor fan 6 that generates an airflow of outdoor air passing through the outdoor heat exchanger to promote heat exchange between the refrigerant flowing in the outdoor heat exchanger and the outdoor air. The outdoor fan 6 is driven by a drive device capable of changing the rotation speed.

[0073] Reference Figure 7The air conditioner 100 further includes a controller 4, which is electrically connected to the air conditioner indoor unit 2 and the air conditioner outdoor unit 1 to control the operation of the components therein, so that the components of the air conditioner 1 operate to realize the predetermined functions of the air conditioner. The controller 4 is at least used to control the operation of the compressor 31, the expansion valve 33, the indoor fan 5, and the outdoor fan 6, so that the air conditioner 100 operates to realize the predetermined functions of the air conditioner 100.

[0074] Those skilled in the art will understand that Figure 7 The circuit structure shown in the figure does not constitute a limitation on the air conditioner 100. The air conditioner 100 may include more or fewer components than shown in the figure, or combine certain components, or arrange the components differently.

[0075] like Figure 8 , Fig. 9 As shown, in this embodiment, the controller 4 has an outdoor control device 42 built into the air conditioner outdoor unit 1 and an indoor control device 41 built into the air conditioner indoor unit 2. The outdoor control device 42 and the indoor control device 41 are used to control the components inside the air conditioner outdoor unit 1 and the air conditioner indoor unit 2, respectively. The outdoor control device 42 and the indoor control device 41 are configured to be connected to each other by a signal line and can send / receive signals to each other. Among them, the outdoor control device 42 of the air conditioner outdoor unit 1 controls the compressor 31, the expansion valve 33 and the outdoor fan 6, etc.

[0076] Fig.10 Schematic diagram of the hardware structure of the outdoor control device 42 of the embodiment of the present application. The outdoor control device 42 includes a rectifier and filter circuit 421, a power module 423, a PFC circuit 422 and a control module 424.

[0077] The rectifier and filter circuit 421 has an electrical interface connected to the AC power supply 7. The AC power supply 7 is connected to the electrical interface of the rectifier and filter circuit 421 to provide a working power supply. The rectifier and filter circuit 421 is used to rectify and filter the AC power supply 7 to output DC power to the input end of the PFC circuit 422.

[0078] The PFC (power factor correction) circuit is used to increase the input voltage and power factor of the compressor 31 when it is turned on. The input end of the PFC circuit 422 is electrically connected to the output end of the rectifier filter circuit 421. The output end of the PFC circuit 422 is electrically connected to the input end of the power module 423 through the DC bus, so that the PFC circuit 422 outputs the DC bus voltage to the power module 423 to provide DC power to the power module 423. The output end of the power module 423 is electrically connected to the compressor 31 to drive the compressor 31 to operate. Among them, the PFC circuit 422 has an electrolytic capacitor, and the control module 424 is electrically connected to the PFC circuit 422 and the power module 423.

[0079] Specifically, the power module 423 may be a three-phase bridge drive circuit including a power switch tube, which may be composed of 6 IGBTs, or 6 MOSFETs, or an intelligent power module IPM (Intelligent Power Module), and may have an anti-parallel diode. In this embodiment, the power module 423 is a three-phase inverter.

[0080] The driving circuit can receive the driving signal output by the control module 424 and drive the operation of the compressor 31 according to the driving signal. The control module 424 can receive the feedback signal of the driving circuit and control the opening or closing of the PFC circuit 422 at the same time.

[0081] It should be noted that the specific method of processing and analyzing the collected signal can be determined according to the signal type and processing requirements, and can be processed by a processing method known in the art, and the present invention is not limited to this. In the present application, the control module 424 can be a processor that can receive and process electrical signals in the prior art. Among them, the processor can be a digital signal processor, a single-chip microcomputer, a microprocessor, a microcontroller, a programmable logic device or any combination thereof. The processor can also be any other device with a processing function, such as a circuit, a device or a software module.

[0082] The controller 4 is electrically connected to the compressor 31 to control the operation of the compressor 31. Fig.11 , is a flow chart of the work performed by the controller 4 when controlling the operation of the compressor in an embodiment of the present invention. The controller 4 is configured to perform steps S1 to S4:

[0083] Step S1: obtaining the operating frequency range and driving frequency of the compressor 31;

[0084] Step S2: According to the preset boundary frequency, the operating frequency range of the compressor 31 is divided into at least two frequency segments; each frequency segment corresponds to a Vdc control upper limit value, and the Vdc control upper limit value corresponding to the frequency segment with a low operating frequency is smaller than the Vdc control upper limit value corresponding to the frequency segment with a high operating frequency;

[0085] Step S3: judging the frequency band currently in which the compressor 31 is located according to the preset boundary frequency and the driving frequency, and determining the Vdc control upper limit value currently corresponding to the compressor 31 according to the corresponding relationship between the frequency band and the Vdc control upper limit value; wherein the Vdc control upper limit value is the upper limit value of the Vdc given value;

[0086] Step S4: outputting the DC bus voltage Vdc to the compressor 31 to drive the compressor 31 to operate.

[0087] In the above embodiment, the controller 4 executes steps S1 to S4, thereby segmenting the operating frequency range of the compressor 31, and using different Vdc control upper limit values ​​to control the compressor 31 in different segmented intervals, so that when the driving frequency is high, the Vdc control upper limit value can be set relatively high, thereby expanding the voltage limit ellipse of the permanent magnet synchronous motor 311 of the compressor 31, and increasing the limit values ​​of the d and q axis currents, which can support higher electromagnetic torque and higher frequency operation; when the driving frequency required to operate is low, the Vdc control upper limit value uses a lower setting value, so that the charging voltage of the electrolytic capacitor is appropriately reduced, and the service life is extended. Although the Vdc upper limit may be triggered due to the increase of the d and q axis currents when the medium and low frequency is overloaded, the cooling and heating capacity at this time is relatively not the first contradiction, and there is no need to increase the Vdc limit to extend the service life of the electrolytic capacitor.

[0088] Furthermore, the air conditioner also includes an indoor temperature sensor and an outdoor temperature sensor, wherein the indoor temperature sensor and the outdoor temperature sensor are both communicatively connected to the controller 4 , and the indoor temperature sensor and the outdoor temperature sensor transmit data information to the controller 4 .

[0089] In some implementations of this embodiment, the indoor temperature sensor is installed on the air-conditioning indoor unit 2 for detecting the indoor ambient temperature and sending the detected indoor ambient temperature to the controller 4 .

[0090] In some implementations of this embodiment, the outdoor temperature sensor is installed on the air-conditioning outdoor unit 1 to detect the outdoor ambient temperature and send the detected outdoor ambient temperature to the controller 4 .

[0091] In step S1, the controller 4 is configured to:

[0092] Step S11: Obtain indoor ambient temperature, set temperature, and outdoor ambient temperature;

[0093] Step S12: determining the target frequency of the compressor 31 according to the indoor ambient temperature, the set temperature, and the outdoor ambient temperature;

[0094] Step S13: Determine the driving frequency F_dri based on the target frequency and the air conditioning system protection frequency reduction or frequency increase prohibition. The air conditioning system protection includes exhaust temperature over-high protection, whole machine current protection, and coil overload / freeze protection.

[0095] After step S11, the controller 4 may execute step S14, which is to determine the operating frequency range of the compressor 31 according to the temperature range of the outdoor ambient temperature, wherein the operating frequency range of the compressor 31 is limited by the maximum allowable operating frequency F_max of the compressor 31 and the minimum allowable operating frequency F_min of the compressor 31.

[0096] refer to Fig.13 In step S2, the preset dividing frequency includes a dividing frequency F_divide, the dividing frequency F_divide is less than the maximum allowable operating frequency F_max of the compressor 31 and greater than the minimum allowable operating frequency F_min of the compressor 31, and the operating frequency range of the compressor 31 is divided into two frequency bands, a Vdc control low frequency band and a Vdc control high frequency band, by using the dividing frequency F_divide; wherein, the value above the dividing frequency F_divide is the Vdc control high frequency band, and the value below the dividing frequency F_divide is the Vdc control low frequency band.

[0097] When the operating frequency range of the compressor 31 is divided into a Vdc control low frequency band and a Vdc control high frequency band, in step S3, if the driving frequency F_dri reaches above the dividing frequency F_divide and below the maximum allowable operating frequency F_max, it is determined that the compressor 31 is currently in the Vdc control high frequency band; if the driving frequency F_dri reaches above the minimum allowable operating frequency F_min and does not reach the dividing frequency F_divide, it is determined that the compressor 31 is currently in the Vdc control low frequency band.

[0098] In some embodiments of the present application, when the AC power supply 7 provides low voltage electricity, the Vdc control upper limit value is Vdc_limit, where reference Fig.14 In step S3, according to the correspondence between the frequency segment and the Vdc control upper limit value, the specific steps of determining the Vdc control upper limit value currently corresponding to the compressor 31 are as follows:

[0099] Step S31: If the driving frequency F_dri is in the Vdc control low frequency band, the corresponding Vdc_limit is a preset constant value Vdc_limit_low; Step S32: If the driving frequency F_dri is in the Vdc control high frequency band, the corresponding Vdc_limit is a preset constant value Vdc_limit_high, wherein Vdc_limit_high>Vdc_limit_low. This setting enables different frequency bands to correspond to different Vdc control upper limit values, ensuring that the Vdc control upper limit value corresponding to the frequency band with low operating frequency is less than the Vdc control upper limit value corresponding to the frequency band with high operating frequency.

[0100] In some other embodiments of the present application, when the AC power supply 7 provides low voltage electricity, the Vdc control upper limit value is Vdc_limit, wherein, Fig.15 In step S3, according to the correspondence between the frequency segment and the Vdc control upper limit value, the specific steps of determining the Vdc control upper limit value currently corresponding to the compressor 31 may also be:

[0101] Step S31: if the driving frequency F_dri is in the Vdc control low frequency band, the corresponding Vdc_limit is a preset constant Vdc_limit_low; Step S32: taking the function f(F_dri) of the driving frequency, if the driving frequency F_dri is in the Vdc control high frequency band, the corresponding Vdc_limit is obtained according to the first logic, i.e., the following formula (1):

[0102] Vdc_limit=Vdc_limit_delta*sat(F_dri)+Vdc_limit_low (1)

[0103] Wherein, Vdc_limit_delta is the maximum bias value of the upper limit of Vdc control in the high frequency band, Vdc_limit_delta can be a constant value, and sat(F_dri) is a saturation function.

[0104] Specifically, the saturation function sat(F_dri) is obtained according to the second logic operation, and the second logic operation is the following formula (2):

[0105]

[0106] Among them, Fig.16 As shown, sat(F_dri) takes the positive part of the horizontal axis frequency, k=1 / deltaF, and deltaF is a preset frequency value belonging to the high frequency band of Vdc control.

[0107] Further, when the AC power supply 7 provides high voltage electricity, the Vdc control upper limit value corresponding to the Vdc control low frequency band and the Vdc control high frequency band is Vdc_limit_hiVol, and when the AC power supply 7 provides low voltage electricity, the Vdc control upper limit value corresponding to the Vdc control low frequency band and the Vdc control high frequency band is Vdc_limit, and Vdc_limit_hiVol is relative to the superimposed lift voltage deltaV.

[0108] That is, Vdc_limit_hiVol is obtained by the following formula (3):

[0109] Vdc_limit_hiVol=Vdc_limit+deltaV (3)

[0110] Among them, Vdc_limit is the Vdc control upper limit value corresponding to the Vdc control low frequency band and the Vdc control high frequency band when the low voltage power supply is used, and deltaV is the lift voltage.

[0111] It should be noted that, in the present application, the voltage range of low voltage electricity is AC140V to AC220V, and the voltage range of high voltage electricity is AC220V to AC270V.

[0112] Furthermore, the control module 424 calculates and determines the Vdc given value corresponding to the DC bus voltage Vdc according to the modulation ratio. It should be noted that the calculation of the Vdc given value is a prior art and will not be described in detail here.

[0113] Specifically, when the modulation ratio is lower than M, the DC bus voltage Vdc is obtained after the AC power supply 7 is rectified and filtered, where M is a constant; when the operating frequency of the compressor 31 increases, the modulation ratio is higher than M(, and the DC bus voltage Vdc is obtained by superimposing ΔV on the voltage of the AC power supply 7 after rectification and filtering, and the DC bus voltage Vdc is the Vdc given value.

[0114] In this embodiment, when the modulation ratio is higher than the preset ratio M, at this time, the DC bus voltage Vdc is the same as the given value of Vdc, and the DC bus voltage Vdc is calculated according to the maximum voltage controlled by the PFC circuit 422 and the output voltage of the rectifier filter circuit 421. The DC bus voltage Vdc is obtained by the following formula (4):

[0115] Vdc=Vdc_pfc*K+Vdc_normal (4)

[0116] Wherein, Vdc_pfc is the maximum voltage controlled by the PFC circuit 422 , Vdc_normal is the output voltage of the rectifier and filter circuit 421 , and K is the proportionality coefficient.

[0117] When the modulation ratio is constant, the given value of the DC bus voltage Vdc is proportional to the maximum stator voltage Umax that the power module 423 can output. The larger the DC bus voltage Vdc is, the larger Umax is.

[0118] Combining the d- and q-axis voltage constraints with the stator winding voltage winding equation of the permanent magnet synchronous motor, the Vdc control upper limit Vdc_limit can be set relatively high, and then the voltage limit ellipse of the permanent magnet synchronous motor is expanded, and the limit values ​​of the d- and q-axis currents are increased, thereby obtaining higher electromagnetic torque and higher frequency.

[0119] See formula (5), formula (6) and formula (7) for details.

[0120]

[0121] u d =R s i d +pψ d -ω r ψ q (6)

[0122] u q =R s i q +pψ q +ω r ψ d (7)

[0123] Where Rs is the stator resistance, ω r is the rotor speed, ψ d , q are the flux of stator d and q windings respectively, and p is the differential operator u d is the d-axis voltage component, u q is the q-axis voltage component, i d is the d-axis component of the stator current, i q is the q-axis component of the stator current.

[0124] When the motor enters steady-state operation, the differential term in the above formula is zero, so the steady-state operation equation of the permanent magnet synchronous motor is:

[0125] u d =R s i d -ω r ψ q (8)

[0126] u q =R s i q +ψ d (9)

[0127] ψ q =L q iq (10)

[0128] ψ d =L d i d +ψ f (11)

[0129] Among them, L d , L q are the d-axis and q-axis inductances respectively; ψ f is the permanent magnet excitation flux.

[0130] Substituting equations (8), (9), (10), and (11) into equation (5), we can obtain the following equation (12):

[0131]

[0132] When the permanent magnet synchronous motor operates in the high speed area, the stator voltage drop of the permanent magnet synchronous motor can be ignored. Therefore, the following formula can be obtained from formula (12):

[0133]

[0134] Due to L d <L q , at this time the equation is an elliptic equation, that is, the voltage limit ellipse.

[0135] The torque formula of permanent magnet synchronous motor is:

[0136] T e =1.5p n i q [ψ f +(L q -L d )i d ] (14)

[0137] Among them, p n is the number of pole pairs of the motor. When the compressor 31 is to run at a higher driving frequency, the Vdc control upper limit value Vdc_limit can be set relatively high, such as Fig.17 As shown, the voltage limit ellipse of the permanent magnet synchronous motor expands. It can be seen from formula (14) that when the d and q axis current components are increased, higher electromagnetic torque and higher frequency operation can be supported.

[0138] The air conditioner also includes a memory, which is electrically connected to the control module 424. The memory may be independent or integrated with the processor. The memory may contain computer program code. The processor is used to execute the computer program code stored in the memory, and the controller 4 controls the operation of the air conditioner and responds to the user's operation through various software control programs stored in the memory. It should be noted that the embodiment of the present application does not impose any restrictions on the type of memory.

[0139] The air conditioner provided by the present invention divides the operating frequency range of the compressor into segments, and uses different Vdc control upper limit values ​​Vdc_limit in different segmented intervals to control the compressor, so that when the driving frequency to be operated is relatively high, the Vdc control upper limit value can be set relatively high, and when the driving frequency to be operated is relatively low, the Vdc control upper limit value uses a lower setting value, which takes into account the high-frequency operation requirements of the compressor and the service life of the electrolytic capacitor. The upper limit frequency of the compressor can be increased without increasing the hardware cost, thereby improving the boundary cooling / heating capacity.

[0140] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. An air conditioner, characterized in that: include: The refrigerant circulation loop allows the refrigerant to circulate in the loop consisting of the compressor, condenser, expansion valve, and evaporator; A compressor, used for compressing the refrigerant gas in a low-temperature and low-pressure state into a refrigerant gas in a high-temperature and high-pressure state and discharging the refrigerant gas to a condenser, wherein the compressor comprises a permanent magnet synchronous motor; A controller is electrically connected to at least the compressor, and the controller is configured to: Obtaining an operating frequency range and a driving frequency of the compressor; According to a preset dividing frequency, the operating frequency range of the compressor is divided into at least two frequency segments, each of the frequency segments corresponds to a Vdc control upper limit value, and the Vdc control upper limit value corresponding to the frequency segment with a low operating frequency is smaller than the Vdc control upper limit value corresponding to the frequency segment with a high operating frequency; According to the preset boundary frequency and the driving frequency, the frequency segment in which the compressor is currently located is judged, and according to the corresponding relationship between the frequency segment and the Vdc control upper limit value, the Vdc control upper limit value currently corresponding to the compressor is determined, The DC bus voltage Vdc is output to the compressor to drive the compressor to operate; wherein the Vdc control upper limit value is the upper limit value of the Vdc given value.

2. The air conditioner according to claim 1, characterized in that: The controller is configured to: Get indoor ambient temperature, set temperature, and outdoor ambient temperature; Determine the target frequency of the compressor according to the indoor ambient temperature, the set temperature, and the outdoor ambient temperature; The driving frequency F_dri is determined based on the target frequency and after the air conditioning system is protected by frequency reduction or frequency increase prohibition.

3. The air conditioner according to claim 2, characterized in that: The operating frequency range of the compressor is determined according to the temperature range of the outdoor ambient temperature, wherein the operating frequency range of the compressor includes a maximum allowable operating frequency of the compressor and a minimum allowable operating frequency of the compressor.

4. The air conditioner according to claim 3, characterized in that: The preset dividing frequency includes a dividing frequency F_divide, which is less than the maximum allowable operating frequency of the compressor and greater than the minimum allowable operating frequency of the compressor, so as to divide the operating frequency range of the compressor into two frequency bands; wherein, the values ​​above the dividing frequency F_divide are the Vdc control high frequency band, and the values ​​below the dividing frequency F_divide are the Vdc control low frequency band.

5. The air conditioner according to claim 4, characterized in that: The controller is powered by an AC power supply. When the AC power supply provides low voltage electricity, the Vdc control upper limit value is Vdc_limit; If the driving frequency F_dri is in the Vdc control low frequency band, the corresponding Vdc_limit is a preset constant value Vdc_limit_low; if the driving frequency F_dri is in the Vdc control high frequency band, the corresponding Vdc_limit is a preset constant value Vdc_limit_high, wherein Vdc_limit_high>Vdc_limit_low.

6. The air conditioner according to claim 4, characterized in that: The controller is powered by an AC power supply. When the AC power supply provides low voltage electricity, the Vdc control upper limit value is Vdc_limit; If the driving frequency F_dri is in the Vdc control low frequency band, the corresponding Vdc_limit is a preset constant value Vdc_limit_low; Take the function f(F_dri) of the driving frequency. If the driving frequency F_dri is in the Vdc control high frequency band, the corresponding Vdc_limit is calculated according to the first logic: Vdc_limit=Vdc_limit_delta*sat(F_dri)+Vdc_limit_low; Among them, Vdc_limit_delta is the maximum bias value of the Vdc control upper limit in the high frequency band, and sat(F_dri) is the saturation function.

7. The air conditioner according to claim 6, characterized in that: The saturation function sat(F_dri) is obtained according to a second logical operation, wherein the second logical operation is: Wherein, sat(F_dri) takes the positive part of the horizontal axis frequency, k=1 / deltaF, and deltaF is a preset frequency value belonging to the high frequency band of Vdc control.

8. The air conditioner according to any one of claims 4 to 7, characterized in that: When the AC power supply provides high voltage electricity, the Vdc control upper limit value corresponding to the Vdc control low frequency band and the Vdc control high frequency band is Vdc_limit_hiVol; when the AC power supply provides low voltage electricity, the Vdc control upper limit value corresponding to the Vdc control low frequency band and the Vdc control high frequency band is Vdc_limit, and Vdc_limit_hiVol is superimposed with a lift voltage deltaV relative to Vdc_limit.

9. The air conditioner according to claim 1, characterized in that: The controller comprises: A rectifier and filter circuit having an electrical interface connected to an AC power source; A power module, an output end of which is electrically connected to the compressor to drive the compressor to operate; A PFC circuit, wherein an input end thereof is electrically connected to an output end of the rectifier and filter circuit, and an output end of the PFC circuit is electrically connected to an input end of the power module via a DC bus, so that the PFC circuit outputs the DC bus voltage to the power module; A control module is electrically connected to the PFC circuit and the power module.

10. The air conditioner according to claim 8, characterized in that: The control module calculates and determines the Vdc given value corresponding to the DC bus voltage Vdc according to the modulation ratio; when the modulation ratio is higher than the preset ratio M, the DC bus voltage Vdc is the same as the Vdc given value, and the DC bus voltage Vdc is calculated according to the maximum voltage controlled by the PFC circuit and the output voltage of the rectifier and filter circuit.

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