An air conditioner and its motor parameter offline identification method

Abstract

The present invention discloses an air conditioner and a method for offline identification of motor parameters thereof. The air conditioner includes an indoor unit, an outdoor unit, and a controller. The outdoor unit is equipped with an outdoor heat exchanger, an outdoor fan, a compressor, a motor, a flow control valve, and a four-way valve. The controller is configured to fix the position of the motor rotor according to the motor current and calculate the motor resistance and voltage error according to the motor voltage and current. A pulse current is injected into the motor with a preset increment amplitude to increase the motor's q-axis current to 0Amp and the motor's d-axis current to the rated current, thereby calculating the motor's d-axis inductance. When the motor's d-axis current reaches the rated current, a high-frequency current and a pulse current are injected into the motor's q-axis current to calculate the motor's q-axis inductance. The present invention increases the d-axis current while passing the pulse current and maintains it at the rated value. Even if the rotor is inserted into the q-axis current, it does not change, thereby enabling accurate identification of the inductance parameter.

Description

Technical Field

[0001] The present invention relates to the technical field of air conditioning, and in particular to an air conditioner and a method for offline identification of motor parameters thereof. Background Art

[0002] Air conditioner MTPA control (maximum torque per ampere) utilizes the motor's inductance parameters, Ld and Lq, to ​​achieve high motor efficiency. However, the changes in Ld and Lq depend on the current, which can lead to delays and errors during actual commissioning. Furthermore, inductance parameters also change with motor aging. If the values ​​of Ld and Lq are incorrect, even if MTPA control is incorrect, the current will still increase, resulting in reduced motor efficiency. Therefore, it is crucial to regularly identify inductance parameters and maintain MTPA performance.

[0003] Currently, inductor parameters are identified when the motor is stopped, but several issues remain. Low-inertia compressors without position sensors are driven by pulsed currents, and Lq cannot be identified through the inductor during shutdown. Because Ld and Lq in interior permanent magnet motors (IPMs) vary with current, Ke parameter identification during motor operation cannot accurately identify Ld and Lq due to current fluctuations, making precise MTPA control impossible. Because Lq and Ld are identified simultaneously, Id and Iq influence each other, making accurate identification of Lq and Ld impossible. Summary of the Invention

[0004] The present invention provides an air conditioner and a method for offline identification of motor parameters thereof, which increases the d-axis current and maintains it at a rated value while passing a pulse current, and does not change the q-axis current even if the rotor is inserted, thereby enabling accurate identification of inductance parameters.

[0005] The air conditioner provided in the first embodiment of the present invention includes:

[0006] Indoor unit, which houses an indoor heat exchanger and an indoor fan;

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

[0008] The indoor heat exchanger is used to act as an evaporator or a condenser according to the operating state of the indoor unit, so as to perform heat exchange between the refrigerant flowing in the heat transfer tube and the air passing through the indoor heat exchanger;

[0009] The outdoor heat exchanger is used to act as a condenser or an evaporator according to the operating state of the outdoor unit, so that the refrigerant flowing in the heat transfer tube and the air passing through the outdoor heat exchanger can exchange heat;

[0010] The flow regulating valve is used to convert the medium-temperature and high-pressure liquid after the outdoor heat exchanger absorbs cold and releases heat into a low-temperature and low-pressure liquid;

[0011] The four-way valve is used to switch between cooling and heating by changing the flow direction of the refrigerant in the circulation loop;

[0012] The controller is configured to fix the position of the motor rotor according to the current of the motor, and calculate the resistance and voltage error of the motor according to the voltage and current of the motor; inject pulse current into the motor with a preset incremental amplitude, increase the q-axis current of the motor to 0Amp, increase the d-axis current of the motor to the rated current, and calculate the d-axis inductance of the motor; when the d-axis current of the motor reaches the rated current, high-frequency current and pulse current are injected into the q-axis current of the motor, and the q-axis inductance of the motor is calculated.

[0013] In the air conditioner provided by the second embodiment of the present invention, the controller is further configured to:

[0014] The resistance of the motor winding is calculated based on the voltage and current of the motor:

[0015] R a =(V d2 -V d1 ) / (I d2 -I d1 );

[0016] Among them, R a Represents the resistance of the motor winding, V d1 Indicates the first voltage of the motor, V d2 Indicates the second voltage of the motor, I d1 Indicates the first current of the motor, I d2 Represents the second current of the motor;

[0017] The voltage error of the motor is calculated based on the voltage and current of the motor:

[0018] ΔV*D d =(V d2 *I d1 -V d1 *I d2 ) / (I d1 -I d2 );

[0019] Where, ΔV*D dIndicates the voltage error of the motor.

[0020] In the air conditioner provided by the third embodiment of the present invention, the calculation formula of the d-axis inductance of the motor is:

[0021]

[0022] Among them, L d represents the d-axis inductance of the motor, T s represents the calculation time, k represents the discrete value, i d (k+1)- d (k) represents T s i between d Current changes, Indicates the d-axis given voltage.

[0023] In the air conditioner provided by the fourth embodiment of the present invention, the calculation formula of the q-axis inductance of the motor is:

[0024]

[0025] Among them, L q represents the q-axis inductance of the motor, i q (k+1)- q (k) represents T s i between q Current changes, Indicates the q-axis given voltage.

[0026] In the air conditioner provided in the fifth embodiment of the present invention, the controller is further configured to:

[0027] When the high-frequency current is injected into the q-axis current of the motor, the effective value of the pulse current is increased to a preset value.

[0028] A sixth embodiment of the present invention provides an off-line identification method for air conditioner motor parameters. The method is applied to an air conditioner including an indoor heat exchanger, an indoor fan, an outdoor heat exchanger, an outdoor fan, a compressor, a motor, a flow control valve, and a four-way valve. The off-line identification method for air conditioner motor parameters includes:

[0029] Fixing the position of the motor rotor according to the current of the motor, and calculating the resistance and voltage error of the motor according to the voltage and current of the motor;

[0030] Injecting a pulse current into the motor with a preset incremental amplitude to increase the q-axis current of the motor to 0 Amp, increasing the d-axis current of the motor to the rated current, and calculating the d-axis inductance of the motor;

[0031] When the d-axis current of the motor reaches the rated current, high-frequency current and pulse current are injected into the q-axis current of the motor, and the q-axis inductance of the motor is calculated.

[0032] In the off-line identification method for air conditioner motor parameters provided by the seventh embodiment of the present invention, the calculation of the resistance and voltage error of the motor based on the voltage and current of the motor specifically includes:

[0033] The resistance of the motor winding is calculated based on the voltage and current of the motor:

[0034] R a =(V d2 -V d1 ) / (I d2 -I d1 );

[0035] Among them, R a Represents the resistance of the motor winding, V d1 Indicates the first voltage of the motor, V d2 Indicates the second voltage of the motor, I d1 Indicates the first current of the motor, I d2 Represents the second current of the motor;

[0036] The voltage error of the motor is calculated based on the voltage and current of the motor:

[0037] ΔV*D d =(V d2 *I d1 -V d1 *I d2 ) / (I d1 -I d2 );

[0038] Where, ΔV*D d Indicates the voltage error of the motor.

[0039] In the off-line identification method for air conditioner motor parameters provided by the eighth embodiment of the present invention, the calculation formula of the d-axis inductance of the motor is:

[0040]

[0041] Among them, L d represents the d-axis inductance of the motor, T s represents the calculation time, k represents the discrete value, i d (k+1)- d (k) represents T s i between d Current changes, Indicates the d-axis given voltage.

[0042] In the off-line identification method for air conditioner motor parameters provided by the ninth embodiment of the present invention, the calculation formula of the q-axis inductance of the motor is:

[0043]

[0044] Among them, L q represents the q-axis inductance of the motor, i q (k+1)- q (k) represents T s i between q Current changes, Indicates the q-axis given voltage.

[0045] In the off-line identification method for air conditioner motor parameters provided by the tenth embodiment of the present invention, the method further includes:

[0046] When the high-frequency current is injected into the q-axis current of the motor, the effective value of the pulse current is increased to a preset value.

[0047] Compared with the prior art, the beneficial effect of an air conditioner and its motor parameter offline identification method provided by an embodiment of the present invention is that: the air conditioner includes an indoor unit, an outdoor unit and a controller. The indoor unit is equipped with an indoor heat exchanger and an indoor fan. The outdoor unit is equipped with an outdoor heat exchanger, an outdoor fan, a compressor, a motor, a flow regulating valve and a four-way valve. The compressor, the flow regulating valve, the four-way valve, the outdoor heat exchanger and the indoor heat exchanger are connected through pipelines to form a refrigerant circulation loop; the indoor heat exchanger is used to act as an evaporator or a condenser according to the operating state of the indoor unit, so that the refrigerant flowing in the heat transfer pipe and the air passing through the indoor heat exchanger are heat exchanged; the outdoor heat exchanger is used to act as a condenser or an evaporator according to the operating state of the outdoor unit, so that the refrigerant flowing in the heat transfer pipe and the air passing through the outdoor heat exchanger are heat exchanged; the flow regulating valve is used to adjust the outdoor heat exchanger to absorb and release cold air. The heated medium-temperature, high-pressure liquid becomes a low-temperature, low-pressure liquid; the four-way valve is used to switch between cooling and heating by changing the flow direction of the refrigerant within the circulation loop; the controller is configured to fix the position of the motor rotor according to the motor current and calculate the motor resistance and voltage error based on the motor voltage and current; pulse current is injected into the motor at a preset increment to increase the motor's q-axis current to 0Amp and the motor's d-axis current to the rated current, and the motor's d-axis inductance is calculated; when the motor's d-axis current reaches the rated current, high-frequency current and pulse current are injected into the motor's q-axis current to calculate the motor's q-axis inductance. This embodiment of the present invention increases the d-axis current while passing the pulse current and maintains it at the rated value. Even if the rotor is inserted into the q-axis current, the d-axis current does not change, thereby enabling accurate identification of the inductance parameter. Furthermore, this embodiment of the present invention reduces interference by separately identifying Ld and Lq, effectively improving identification accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 This is a perspective view of the appearance of an air conditioner provided by one embodiment of the present invention;

[0049] Figure 2 This is a structural diagram of an air conditioner provided by one embodiment of the present invention;

[0050] Figure 3 This is a schematic diagram of a refrigerant circulation circuit of an air conditioner provided by one embodiment of the present invention;

[0051] Figure 4 This is a schematic diagram of a first change of a pulse current in an air conditioner provided by one embodiment of the present invention;

[0052] Figure 5 This is a schematic diagram of a second change of a pulse current in an air conditioner provided by one embodiment of the present invention;

[0053] Figure 6 1 is a third schematic diagram of a change in pulse current in an air conditioner provided by one embodiment of the present invention;

[0054] Figure 7 1 is a schematic diagram showing the variation of inductance with current in an air conditioner provided by one embodiment of the present invention;

[0055] Figure 8 This is an inductance curve diagram of an air conditioner provided by one embodiment of the present invention;

[0056] Figure 9 1 is a flow chart of an off-line identification method for air conditioner motor parameters provided by an embodiment of the present invention;

[0057] Figure 10 The figure is a schematic diagram of a calculation flow of a voltage error in an off-line identification method for air conditioner motor parameters provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0058] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0059] In the description of this application, 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 accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0060] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature specified as "first" or "second" may explicitly or implicitly include one or more of such features. Throughout this application, unless otherwise specified, "plurality" means two or more.

[0061] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0062] See also Figures 1 to 2 , Figure 1 This is a perspective view of the appearance of an air conditioner provided by one embodiment of the present invention. Figure 2 FIG1 is a structural diagram of an air conditioner provided in one embodiment of the present invention. The air conditioner 1 provided in the embodiment of the present invention comprises:

[0063] Indoor unit 2, which is equipped with indoor heat exchanger 21 and indoor fan 22;

[0064] The outdoor unit 3 includes an outdoor heat exchanger 31, an outdoor fan 32, a compressor 33, a motor 34, a flow regulating valve 35, and a four-way valve 36. The compressor 33, the flow regulating valve 35, the four-way valve 36, the outdoor heat exchanger 31, and the indoor heat exchanger 21 are connected by pipelines to form a refrigerant circulation loop.

[0065] The indoor heat exchanger 21 is used to act as an evaporator or a condenser according to the operating state of the indoor unit 2, so that the refrigerant flowing in the heat transfer tube and the air passing through the indoor heat exchanger can exchange heat;

[0066] The outdoor heat exchanger 31 is used to act as a condenser or an evaporator according to the operating state of the outdoor unit 3, so that the refrigerant flowing in the heat transfer tube and the air passing through the outdoor heat exchanger can exchange heat;

[0067] The flow regulating valve 35 is used to convert the medium-temperature and high-pressure liquid after the outdoor heat exchanger 31 absorbs cold and releases heat into a low-temperature and low-pressure liquid;

[0068] The four-way valve 36 is used to switch between cooling and heating by changing the flow direction of the refrigerant in the circulation loop;

[0069] The controller is configured to fix the position of the motor rotor according to the current of the motor 34, and calculate the resistance and voltage error of the motor according to the voltage and current of the motor 34; inject pulse current into the motor 34 with a preset incremental amplitude, increase the q-axis current of the motor 34 to 0Amp, increase the d-axis current of the motor 34 to the rated current, and calculate the d-axis inductance of the motor 34; when the d-axis current of the motor 34 reaches the rated current, the q-axis current of the motor 34 is injected with high-frequency current and pulse current, and the q-axis inductance of the motor 34 is calculated.

[0070] Specifically, the air conditioner 1 in the embodiment of the present invention includes an indoor unit 2. Taking the indoor wall mounted unit (shown in the figure) as an example, the indoor wall mounted unit is usually installed on the indoor wall. For another example, the indoor cabinet unit (not shown in the figure) is also a form of indoor unit. The outdoor unit 3 is usually installed outdoors and is used for heat exchange in the indoor environment. In addition, Figure 1In the illustration, the outdoor unit 3 is shown with a dashed line because it is located outdoors on the opposite side of the indoor unit 2, separated by a wall. The indoor unit 2 and the outdoor unit 3 are connected by a connecting pipe 4. The indoor unit 2 houses an indoor heat exchanger 21 and an indoor fan 22. The indoor heat exchanger 21 consists of a plurality of fins and a coil extending through the fins. Depending on the operating state of the indoor unit 2, the indoor heat exchanger 21 functions as an evaporator or a radiator, exchanging heat between the refrigerant flowing through the coil and the air passing through the indoor heat exchanger 21. The indoor fan 22 is located approximately in the center of the indoor unit casing. It is a cross-flow fan that is elongated in the longitudinal direction (left-right direction) of the indoor unit 2. As the indoor fan 22 rotates, indoor air is drawn in through the air inlet, passes through the air filter, and then passes through the indoor heat exchanger 21. The resulting conditioned air is then blown out through the outlet into the room. The higher the speed of the indoor fan 22, the greater the volume of conditioned air blown out of the outlet. When the air conditioner is in cooling mode, the indoor heat exchanger 21 operates as an evaporator. Depending on the operating state of the indoor unit, the indoor heat exchanger 21 functions as either an evaporator or a radiator, exchanging heat between the refrigerant flowing through the heat transfer tubes and the air passing through the indoor heat exchanger. The indoor fan 22 generates airflow through the indoor heat exchanger 21 to facilitate heat exchange between the refrigerant flowing through the heat transfer tubes of the indoor heat exchanger 21 and the indoor air. The outdoor unit 3 includes an outdoor heat exchanger 31, an outdoor fan 32, a compressor 33, a motor 34, a flow control valve 35, and a four-way valve 36. The outdoor fan 32 generates airflow through the outdoor heat exchanger 31 to facilitate heat exchange between the refrigerant flowing through the heat transfer tubes and the outdoor air. The outdoor fan 32 is driven by an outdoor motor with a variable speed. When the air conditioner is in cooling mode, the outdoor heat exchanger 31 operates as a condenser. The outdoor fan 32 generates an airflow of outdoor air through the outdoor heat exchanger 31 to promote heat exchange between the refrigerant flowing in the heat transfer tubes of the outdoor heat exchanger 31 and the outdoor air.

[0071] See also Figure 3 , Figure 3The figure is a schematic diagram of a refrigerant circulation circuit for an air conditioner provided in one embodiment of the present invention. A compressor 33, a flow control valve 35, a four-way valve 36, an outdoor heat exchanger 31, and an indoor heat exchanger 21 are connected by pipes to form a refrigerant circulation circuit. The indoor heat exchanger 21 and the outdoor heat exchanger 31 function as a condenser or an evaporator. When the indoor heat exchanger 21 functions as a condenser and the outdoor heat exchanger 31 functions as an evaporator, the air conditioner functions as a heater in heating mode; when the indoor heat exchanger 21 functions as an evaporator and the outdoor heat exchanger 31 functions as a condenser, the air conditioner functions as a cooler in cooling mode. The four-way valve 36 is used to control the flow direction of the refrigerant in the refrigerant circulation circuit so that the outdoor heat exchanger and the indoor heat exchanger can switch between functioning as a condenser and an evaporator. When the air conditioner is in cooling mode, the indoor heat exchanger 21 and the outdoor heat exchanger 31 function as an evaporator and a condenser, respectively. The refrigerant is compressed by the compressor and transformed into a high-temperature, high-pressure gas. It then passes through a four-way valve and enters the outdoor heat exchanger of the outdoor unit. There, it absorbs cold air and releases heat, becoming a medium-temperature, high-pressure liquid. After passing through a flow control valve, it becomes a low-temperature, low-pressure liquid. After absorbing heat and releasing heat in the indoor heat exchanger of the indoor unit, it becomes a low-temperature, low-pressure gas. It then passes through the four-way valve and returns to the compressor, continuing its cycle. The refrigerant circulation in the refrigerant circuit enables a vapor compression refrigeration cycle. The flow control valve can change its opening. Reducing the opening increases the flow resistance of the refrigerant through the flow control valve, while increasing the opening decreases the flow resistance. During cooling operation, this flow control valve expands and decompresses the refrigerant flowing from the indoor heat exchanger to the outdoor heat exchanger. Furthermore, even if the conditions of other components in the refrigerant circuit remain unchanged, changes in the opening of the flow control valve can change the flow rate of the refrigerant flowing through the refrigerant circuit.

[0072] This embodiment of the present invention increases the d-axis current while passing the pulse current and maintains it at the rated value. Even when the rotor is inserted, the q-axis current remains unchanged, enabling accurate identification of inductance parameters. Furthermore, by separately identifying Ld and Lq, this embodiment of the present invention reduces interference and effectively improves identification accuracy.

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

[0074] The resistance of the motor winding is calculated based on the voltage and current of the motor:

[0075] R a =(V d2 -V d1 ) / (I d2 -I d1 );

[0076] Among them, Ra Indicates the resistance of the motor winding, B f1 Indicates the first voltage of the motor, B f2 Indicates the second voltage of the motor, I f1 Indicates the first current of the motor, I d2 Represents the second current of the motor;

[0077] The voltage error of the motor is calculated based on the voltage and current of the motor:

[0078] ΔV*D d =(V d2 *I d1 -V d1 *I d2 ) / (I d1 -I d2 );

[0079] Where, ΔV*D d Indicates the voltage error of the motor.

[0080] For example, in the embodiment of the present invention, when the rotor position is at 0°, the motor d-axis current I d1 The amplitude is set in the range of 3 to 8A to fix the rotor position; when the rotor position is 0°, the motor d-axis current I d2 The amplitude is set in the range of 1 to 5A to fix the rotor position. The stator voltage equation is:

[0081]

[0082] Among them, v d_ref Indicates the d-axis given voltage, v q_ref represents the q-axis given voltage, ω represents the compressor angular velocity, ΔVDd represents the voltage error caused by the dead time, L d and L q They represent the d-axis inductance and q-axis inductance respectively, Represents magnetic flux.

[0083] Since the rotor is fixed, the compressor angular velocity ω is 0, then:

[0084]

[0085] Performing discrete transformation on the above determinant, we get the following formula:

[0086]

[0087] Wherein, k is a discrete sampling value, k = 1, 2, 3, ···, N.

[0088] Then the d-axis current value is:

[0089]

[0090] Assuming that the current reaches a stable condition, the above formula can be simplified to:

[0091]

[0092] According to the above obtained linear equation, R a is its slope, ΔV*D d is its intercept.

[0093] Therefore, according to the voltage and current of the motor and the formula R a =(V d2 -V d1 ) / (I d2 -I d1 ) Calculate the resistance R of the motor winding a , where V d1 Indicates the first voltage of the motor, V d2 Indicates the second voltage of the motor, I d1 Indicates the first current of the motor, I d2 Represents the second current of the motor. According to the voltage and current of the motor and the formula ΔV*D d =(V d2 *I d1 -V d1 *I d2 ) / (I d1 -I d2 ) Calculate the motor voltage error ΔV*D d .

[0094] As one of the optional embodiments, the calculation formula of the d-axis inductance of the motor is:

[0095]

[0096] Among them, L d represents the d-axis inductance of the motor, T s represents the calculation time, k represents the discrete value, i d (k+1)- d (k) represents T s i between d Current changes, Indicates the d-axis given voltage.

[0097] For details, please refer to Figure 4 and Figure 5 , Figure 4 FIG. 1 is a first schematic diagram of a change in a pulse current in an air conditioner provided by an embodiment of the present invention. Figure 5This is a second schematic diagram of a pulse current variation in an air conditioner provided by one embodiment of the present invention. To identify Ld, the present embodiment injects pulse current into the motor according to a preset increment. For example, the pulse current is injected in increments of 10% to 20%. Figure 4 This corresponds to the case where Ts is very long. By increasing the change in each Step, the recognition accuracy of Ld can be improved. Figure 5 When Ts is short, the change is made in a step-by-step manner because of the higher accuracy. Increase the motor's q-axis current Iq to 0Amp to stop the motor, and increase the motor's d-axis current Id to the rated current according to the formula:

[0098]

[0099] After transforming the above formula, the results are as follows:

[0100]

[0101] Then the d-axis inductance of the motor is calculated as:

[0102]

[0103] As one of the optional embodiments, the calculation formula of the q-axis inductance of the motor is:

[0104]

[0105] Among them, L q represents the q-axis inductance of the motor, i q (k+1)- q (k) represents T s i between q Current changes, Indicates the q-axis given voltage.

[0106] Specifically, when the d-axis current Id of the motor reaches the rated current, the q-axis current Iq of the motor is injected with a high-frequency current on the basis of the pulse current of the preset incremental amplitude, according to the formula:

[0107]

[0108] The q-axis inductance of the motor is calculated as:

[0109]

[0110] As one of the optional embodiments, the controller is further configured to:

[0111] When the high-frequency current is injected into the q-axis current Iq of the motor, the effective value of the pulse current is increased to a preset value.

[0112] For details, please refer to Figure 6 , Figure 6 This is a third variation diagram of a pulse current in an air conditioner provided by an embodiment of the present invention. In this embodiment of the present invention, when the q-axis current of the motor is injected with a high-frequency current, the effective value of the pulse current is increased to a preset value (200 Hz to 3 kHz).

[0113] See also Figure 7 and Figure 8 , Figure 7 FIG1 is a schematic diagram showing the variation of inductance with current in an air conditioner provided by an embodiment of the present invention. Figure 8 This is an inductance curve diagram of an air conditioner provided by one embodiment of the present invention.

[0114] Create a table or function that correlates the identified Ld with the Id parameter. Similarly, create a table or function that correlates Lq with Iq. Then, based on the current, substitute Lq and Ld into the MTPA formula to calculate the command value for Id:

[0115]

[0116] Because Ld and Lq change linearly according to the changes in Iq and Id, it is very important to accurately grasp their parameters, tabulate them and reflect them in the logic of the MTPA. Usually, it takes about a month to analyze and measure Ld and Lq. In addition, Ld and Lq will change due to years of degradation, resulting in deviations in the measured values ​​and poor performance of the MTPA. However, the embodiment of the present invention increases the d-axis current and maintains it at the rated value while passing the pulse current. Even if the rotor is inserted, the q-axis current will not change, thereby enabling accurate identification of the inductance parameters. In addition, the embodiment of the present invention reduces interference and effectively improves the accuracy of identification by identifying Ld and Lq separately. If regular parameter identification is performed using the motor parameter offline identification method provided by the embodiment of the present invention, the inductance can be regularly identified in a short time, thereby always maintaining the performance of the MTPA.

[0117] See also Figure 9 , Figure 9The figure is a flow chart of an off-line identification method for air conditioner motor parameters provided by one embodiment of the present invention. An air conditioner motor parameter offline identification method provided in an embodiment of the present invention is applied to an air conditioner including an indoor heat exchanger, an indoor fan, an outdoor heat exchanger, an outdoor fan, a compressor, a motor, a flow control valve, and a four-way valve; the compressor, the flow control valve, the four-way valve, the outdoor heat exchanger, and the indoor heat exchanger are connected by pipelines to form a refrigerant circulation loop; the indoor heat exchanger is used to act as an evaporator or a condenser according to the operating state of the indoor unit, so that the refrigerant flowing in the heat transfer tube exchanges heat with the air passing through the indoor heat exchanger; the outdoor heat exchanger is used to act as a condenser or an evaporator according to the operating state of the outdoor unit, so that the refrigerant flowing in the heat transfer tube exchanges heat with the air passing through the outdoor heat exchanger; the flow control valve is used to convert the medium-temperature and high-pressure liquid after absorbing cold and releasing heat in the outdoor heat exchanger into a low-temperature and low-pressure liquid; the four-way valve is used to achieve switching between cooling and heating by changing the flow direction of the refrigerant in the circulation loop. The air conditioner motor parameter offline identification method includes:

[0118] S1. Fixing the position of the motor rotor according to the current of the motor, and calculating the resistance and voltage error of the motor according to the voltage and current of the motor;

[0119] S2. Injecting a pulse current into the motor with a preset incremental amplitude to increase the q-axis current of the motor to 0 Amp, increase the d-axis current of the motor to the rated current, and calculate the d-axis inductance of the motor;

[0120] S3. When the d-axis current of the motor reaches the rated current, a high-frequency current and a pulse current are injected into the q-axis current of the motor, and the q-axis inductance of the motor is calculated.

[0121] This embodiment of the present invention increases the d-axis current while passing the pulse current and maintains it at the rated value. Even when the rotor is inserted, the q-axis current remains unchanged, enabling accurate identification of inductance parameters. Furthermore, by separately identifying Ld and Lq, this embodiment of the present invention reduces interference and effectively improves identification accuracy.

[0122] See also Figure 10 , Figure 10 The figure is a schematic diagram of a calculation flow of a voltage error in an off-line identification method for air conditioner motor parameters provided by an embodiment of the present invention.

[0123] As one of the optional embodiments, calculating the resistance and voltage error of the motor according to the voltage and current of the motor specifically includes:

[0124] The resistance of the motor winding is calculated based on the voltage and current of the motor:

[0125] R a =(V d2 -V d1 ) / (I d2 -I d1 );

[0126] Among them, R a Represents the resistance of the motor winding, V d1 Indicates the first voltage of the motor, V d2 Indicates the second voltage of the motor, I d1 Indicates the first current of the motor, I d2 Represents the second current of the motor;

[0127] The voltage error of the motor is calculated based on the voltage and current of the motor:

[0128] ΔV*D d =(V d2 *I d1 -V d1 *I d2 ) / (I d1 -I d2 );

[0129] Where, ΔV*D d Indicates the voltage error of the motor.

[0130] For example, in the embodiment of the present invention, when the rotor position is at 0°, the motor d-axis current I d1 The amplitude is set in the range of 3 to 8A to fix the rotor position; when the rotor position is 0°, the motor d-axis current I d2 The amplitude is set in the range of 1 to 5A to fix the rotor position. The stator voltage equation is:

[0131]

[0132] Among them, v d_ref Indicates the d-axis given voltage, v q_ref represents the q-axis given voltage, ω represents the compressor angular velocity, ΔVDd represents the voltage error caused by the dead time, L d and L q They represent the d-axis inductance and q-axis inductance respectively, Represents magnetic flux.

[0133] Since the rotor is fixed, the compressor angular velocity ω is 0, then:

[0134]

[0135] Performing discrete transformation on the above determinant, we get the following formula:

[0136]

[0137] Wherein, k is a discrete sampling value, k = 1, 2, 3, ···, N.

[0138] Then the d-axis current value is:

[0139]

[0140] Assuming that the current reaches a stable condition, the above formula can be simplified to:

[0141]

[0142] According to the above obtained linear equation, R a is its slope, ΔV*D d is its intercept.

[0143] Therefore, according to the voltage and current of the motor and the formula R a =(V d2 -V d1 ) / (I d2 -I d1 ) Calculate the resistance R of the motor winding a , where V d1 Indicates the first voltage of the motor, V d2 Indicates the second voltage of the motor, I d1 Indicates the first current of the motor, I d2 Represents the second current of the motor. According to the voltage and current of the motor and the formula ΔV*D d =(V d2 *I d1 -V d1 *I d2 ) / (I d1 -I d2 ) Calculate the motor voltage error ΔV*D d .

[0144] As one of the optional embodiments, the calculation formula of the d-axis inductance of the motor is:

[0145]

[0146] Among them, L d represents the d-axis inductance of the motor, T s represents the calculation time, k represents the discrete value, i d (k+1)- d (k) represents T s i between d Current changes, Indicates the d-axis given voltage.

[0147] As one of the optional embodiments, the calculation formula of the q-axis inductance of the motor is:

[0148]

[0149] Among them, L q represents the q-axis inductance of the motor, i q (k+1)-i q (k) represents T s i between q Current changes, Indicates the q-axis given voltage.

[0150] Specifically, in order to identify Ld, the embodiment of the present invention injects pulse current into the motor according to a preset increment. For example, the pulse current is injected in increments of 10% to 20%. The q-axis current Iq of the motor is increased to 0Amp to stop the motor, and the d-axis current Id of the motor is increased to the rated current according to the formula:

[0151]

[0152] After transforming the above formula, the results are as follows:

[0153]

[0154] Then the d-axis inductance of the motor is calculated as:

[0155]

[0156] When the motor's d-axis current Id reaches the rated current, the motor's q-axis current Iq is injected with a high-frequency current in addition to the pulse current of the preset incremental amplitude. According to the formula:

[0157]

[0158] The q-axis inductance of the motor is calculated as:

[0159]

[0160] As an optional embodiment, the method further includes:

[0161] When the high-frequency current is injected into the q-axis current of the motor, the effective value of the pulse current is increased to a preset value.

[0162] Specifically, in the embodiment of the present invention, when the q-axis current of the motor is injected with a high-frequency current, the effective value of the pulse current is increased to a preset value (200 Hz to 3 kHz).

[0163] An embodiment of the present invention provides an air conditioner and a method for offline identification of motor parameters thereof. The air conditioner includes an indoor unit, an outdoor unit and a controller. An indoor heat exchanger and an indoor fan are provided in the indoor unit. An outdoor heat exchanger, an outdoor fan, a compressor, a motor, a flow regulating valve and a four-way valve are provided in the outdoor unit. The compressor, the flow regulating valve, the four-way valve, the outdoor heat exchanger and the indoor heat exchanger are connected through pipelines to form a refrigerant circulation loop; the indoor heat exchanger is used to act as an evaporator or a condenser according to the operating state of the indoor unit, so that the refrigerant flowing in the heat transfer pipe is heat-exchanged with the air passing through the indoor heat exchanger; the outdoor heat exchanger is used to act as a condenser or an evaporator according to the operating state of the outdoor unit, so that the refrigerant flowing in the heat transfer pipe is heat-exchanged with the air passing through the outdoor heat exchanger; the flow regulating valve is used to adjust the outdoor heat exchanger to absorb and release cold air. The heated medium-temperature, high-pressure liquid becomes a low-temperature, low-pressure liquid; the four-way valve is used to switch between cooling and heating by changing the flow direction of the refrigerant within the circulation loop; the controller is configured to fix the position of the motor rotor according to the motor current and calculate the motor resistance and voltage error based on the motor voltage and current; pulse current is injected into the motor at a preset increment to increase the motor's q-axis current to 0Amp and the motor's d-axis current to the rated current, and the motor's d-axis inductance is calculated; when the motor's d-axis current reaches the rated current, high-frequency current and pulse current are injected into the motor's q-axis current to calculate the motor's q-axis inductance. This embodiment of the present invention increases the d-axis current while passing the pulse current and maintains it at the rated value. Even if the rotor is inserted into the q-axis current, the d-axis current does not change, thereby enabling accurate identification of the inductance parameter. Furthermore, this embodiment of the present invention reduces interference by separately identifying Ld and Lq, effectively improving identification accuracy.

[0164] It should be noted that the system embodiment described above is merely illustrative, wherein the units described as separate components may or may not be physically separate, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed across multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the present embodiment. In addition, in the drawings of the system embodiment provided by the present invention, the connection relationship between the modules indicates that there is a communication connection between them, which can be specifically implemented as one or more communication buses or signal lines. A person of ordinary skill in the art can understand and implement the present invention without inventive work.

[0165] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. An air conditioner, characterized in that: include: Indoor unit, which houses an indoor heat exchanger and an indoor fan; An outdoor unit is provided with an outdoor heat exchanger, an outdoor fan, a compressor, a motor, a flow regulating valve and a four-way valve, wherein the compressor, the flow regulating valve, the four-way valve, the outdoor heat exchanger and the indoor heat exchanger are connected by pipelines to form a refrigerant circulation loop; The indoor heat exchanger is used to act as an evaporator or a condenser according to the operating state of the indoor unit, so as to perform heat exchange between the refrigerant flowing in the heat transfer tube and the air passing through the indoor heat exchanger; The outdoor heat exchanger is used to act as a condenser or an evaporator according to the operating state of the outdoor unit, so that the refrigerant flowing in the heat transfer tube and the air passing through the outdoor heat exchanger can exchange heat; The flow regulating valve is used to convert the medium-temperature and high-pressure liquid after the outdoor heat exchanger absorbs cold and releases heat into a low-temperature and low-pressure liquid; The four-way valve is used to switch between cooling and heating by changing the flow direction of the refrigerant in the circulation loop; The controller is configured to fix the position of the motor rotor according to the current of the motor, and calculate the resistance and voltage error of the motor according to the voltage and current of the motor; inject pulse current into the motor with a preset incremental amplitude, increase the q-axis current of the motor to 0Amp, increase the d-axis current of the motor to the rated current, and calculate the d-axis inductance of the motor; when the d-axis current of the motor reaches the rated current, high-frequency current and pulse current are injected into the q-axis current of the motor, and the q-axis inductance of the motor is calculated.

2. The air conditioner according to claim 1, wherein The controller is further configured to: The resistance of the motor winding is calculated based on the voltage and current of the motor: R a =(V d2 -V d1 ) / (I d2 -I d1 ); Among them, R a Represents the resistance of the motor winding, V d1 Indicates the first voltage of the motor, V d2 Indicates the second voltage of the motor, I d1 Indicates the first current of the motor, I d2 Represents the second current of the motor; The voltage error of the motor is calculated based on the voltage and current of the motor: ΔV*D d =(V d2 *I d1 -V d1 *I d2 ) / (I d1 -I d2 ); Where, ΔV*D d Indicates the voltage error of the motor.

3. The air conditioner according to claim 2, wherein: The calculation formula of the d-axis inductance of the motor is: Among them, L d represents the d-axis inductance of the motor, T s represents the calculation time, k represents the discrete value, i d (k+1)-i d (k) represents T s i between d Current change, V d_ref Indicates the d-axis given voltage.

4. The air conditioner according to claim 3, wherein: The calculation formula of the q-axis inductance of the motor is: Among them, L q represents the q-axis inductance of the motor, i q (k+1)-i q (k) represents T s i between q Current change, V q_ref Indicates the q-axis given voltage.

5. The air conditioner according to claim 4, wherein: The controller is further configured to: When the high-frequency current is injected into the q-axis current of the motor, the effective value of the pulse current is increased to a preset value.

6. An off-line identification method for air conditioner motor parameters, characterized in that: The method is applied to an air conditioner including an indoor heat exchanger, an indoor fan, an outdoor heat exchanger, an outdoor fan, a compressor, a motor, a flow regulating valve, and a four-way valve. The method for offline identification of motor parameters of the air conditioner includes: Fixing the position of the motor rotor according to the current of the motor, and calculating the resistance and voltage error of the motor according to the voltage and current of the motor; Injecting a pulse current into the motor with a preset incremental amplitude to increase the q-axis current of the motor to 0 Amp, increasing the d-axis current of the motor to the rated current, and calculating the d-axis inductance of the motor; When the d-axis current of the motor reaches the rated current, high-frequency current and pulse current are injected into the q-axis current of the motor, and the q-axis inductance of the motor is calculated.

7. The method for offline identification of air conditioner motor parameters according to claim 6, wherein: The step of calculating the resistance and voltage error of the motor according to the voltage and current of the motor specifically includes: The resistance of the motor winding is calculated based on the voltage and current of the motor: R a =(V d2 -V d1 ) / (I d2 -I d1 ); Among them, R a Represents the resistance of the motor winding, V d1 Indicates the first voltage of the motor, V d2 Indicates the second voltage of the motor, I d1 Indicates the first current of the motor, I d2 Represents the second current of the motor; The voltage error of the motor is calculated based on the voltage and current of the motor: ΔV*D d =(V d2 *I d1 -V d1 *I d2 ) / (I d1 -I d2 ); Where, ΔV*D d Indicates the voltage error of the motor.

8. The method for offline identification of air conditioner motor parameters according to claim 7, wherein: The calculation formula of the d-axis inductance of the motor is: Among them, L d represents the d-axis inductance of the motor, T s represents the calculation time, k represents the discrete value, i d (k+1)-i d (k) represents T s i between d Current change, V d_ref Indicates the d-axis given voltage.

9. The method for offline identification of air conditioner motor parameters according to claim 8, wherein: The calculation formula of the q-axis inductance of the motor is: Among them, L q represents the q-axis inductance of the motor, i q (k+1)-i q (k) represents T s i between q Current change, V q_ref Indicates the q-axis given voltage.

10. The off-line identification method for air conditioner motor parameters according to claim 9, wherein: The method further comprises: When the high-frequency current is injected into the q-axis current of the motor, the effective value of the pulse current is increased to a preset value.

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