Home appliance and control method thereof

Abstract

The application provides a household appliance and a control method thereof. The household appliance comprises a shell, a permanent magnet synchronous motor and a controller. The permanent magnet synchronous motor is arranged in the shell and is used for performing speed control of the permanent magnet synchronous motor according to a direct current input voltage. The controller is configured to obtain a set shaft voltage value of the permanent magnet synchronous motor, judge whether the permanent magnet synchronous motor satisfies a condition of field weakening control, and control the permanent magnet synchronous motor to switch between first field weakening control and second field weakening control according to the set shaft voltage value of the permanent magnet synchronous motor and a preset voltage threshold when the permanent magnet synchronous motor satisfies the condition of field weakening control. The application enables the permanent magnet synchronous motor to quickly respond within the preset voltage threshold when the permanent magnet synchronous motor is in the first field weakening control, and the timeliness is good. When the permanent magnet synchronous motor is in the second field weakening control, the permanent magnet synchronous motor can further weaken the field in the extreme case of exceeding the preset voltage threshold, the speed of the permanent magnet synchronous motor is improved, and higher speed demand is met.

Description

Technical Field

[0001] This invention relates to the field of home appliance technology, and in particular to a home appliance and its control method. Background Technology

[0002] In household appliances, permanent magnet synchronous motors need to operate at high speeds, such as 16,000 rpm or higher, to meet the operational requirements. However, under normal bus voltage, the voltage demand of a permanent magnet synchronous motor cannot be met when it operates at high speed. Therefore, field weakening control is implemented, increasing the reluctance torque to reduce the voltage demand and allow the motor to reach the required speed.

[0003] Currently, when controlling the speed of a permanent magnet synchronous motor (PMSM), methods such as voltage loop field weakening or lead angle field weakening control the reluctance current and permanent magnet current through voltage loop or current control angle. With adaptive loop design, a relatively fast response can be achieved. However, as the speed increases, the current increases to a certain extent, and due to the limitation of permanent magnet torque output, it cannot continue to weaken the field further. This prevents the PMSM speed from increasing further, failing to meet the high-speed operation requirements of household appliances such as washing machines. Using a single current loop field weakening, the reluctance current is directly controlled through the speed loop, achieving a deeper level of field weakening. However, the speed loop is significantly affected by the observer, resulting in a slow response and poor timeliness, failing to meet the main controller's requirements for rapid changes in PMSM speed. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art.

[0005] Therefore, one object of the present invention is to provide a household appliance that enables a permanent magnet synchronous motor to respond quickly within a preset voltage threshold during the first field weakening control, with good timeliness, and enables the permanent magnet synchronous motor to further weaken the field when the preset voltage threshold is exceeded during the second field weakening control, thereby increasing the speed of the permanent magnet synchronous motor and meeting the demand for higher speed.

[0006] Therefore, a second objective of this invention is to provide a method for controlling household appliances.

[0007] To achieve the above objectives, an embodiment of the first aspect of the present invention provides a household appliance comprising: a housing; a permanent magnet synchronous motor disposed within the housing for controlling the speed of the permanent magnet synchronous motor based on a DC input voltage; and a controller configured to: acquire a set shaft voltage value of the permanent magnet synchronous motor; determine whether the permanent magnet synchronous motor meets the conditions for field weakening control; and, when the permanent magnet synchronous motor meets the conditions for field weakening control, control the permanent magnet synchronous motor to switch between a first field weakening control and a second field weakening control based on the set shaft voltage value of the permanent magnet synchronous motor and a preset voltage threshold.

[0008] According to the home appliance of the present invention, the set shaft voltage value of the permanent magnet synchronous motor is obtained, and it is determined whether the permanent magnet synchronous motor meets the field weakening control conditions. When the permanent magnet synchronous motor meets the field weakening control conditions, the permanent magnet synchronous motor is controlled to perform field weakening control. The permanent magnet synchronous motor is adaptively switched between the first field weakening control and the second field weakening control according to the relationship between the set shaft voltage value of the permanent magnet synchronous motor and the preset voltage threshold. This allows the permanent magnet synchronous motor to respond quickly within the preset voltage threshold during the first field weakening control, with good timeliness. During the second field weakening control, the permanent magnet synchronous motor can further weaken the field when the voltage threshold is exceeded, thereby increasing the speed of the permanent magnet synchronous motor and meeting the demand for higher speeds.

[0009] In some embodiments, before controlling the permanent magnet synchronous motor to switch between first field weakening control and second field weakening control based on the set shaft voltage value and preset voltage threshold of the permanent magnet synchronous motor, the controller is further configured to control the permanent magnet synchronous motor to perform first field weakening control.

[0010] In some embodiments, when the set shaft voltage value is the quadrature shaft voltage value, the permanent magnet synchronous motor is controlled to switch between a first field weakening control and a second field weakening control based on the quadrature shaft voltage value and a preset voltage threshold. The controller is configured to: control the permanent magnet synchronous motor to switch to the second field weakening control or maintain in the second field weakening control when the quadrature shaft voltage value is less than the first preset voltage threshold; and control the permanent magnet synchronous motor to switch to the first field weakening control or maintain in the first field weakening control when the quadrature shaft voltage value is greater than the second preset voltage threshold, wherein the first preset voltage threshold is less than the second preset voltage threshold.

[0011] In some embodiments, the controller is further configured to: when the quadrature-axis voltage value is between the first preset voltage threshold and the second preset voltage threshold, if the permanent magnet synchronous motor is under the first field weakening control, then control the permanent magnet synchronous motor to maintain under the first field weakening control; when the quadrature-axis voltage value is between the first preset voltage threshold and the second preset voltage threshold, if the permanent magnet synchronous motor is under the second field weakening control, then control the permanent magnet synchronous motor to maintain under the second field weakening control.

[0012] In some embodiments, when the set shaft voltage value is the direct shaft voltage value, the permanent magnet synchronous motor is controlled to switch between a first field weakening control and a second field weakening control based on the direct shaft voltage value and a preset voltage threshold. The controller is configured to: control the permanent magnet synchronous motor to switch to the second field weakening control or maintain in the second field weakening control when the absolute value of the direct shaft voltage value is less than the first preset voltage threshold; and control the permanent magnet synchronous motor to switch to the first field weakening control or maintain in the first field weakening control when the absolute value of the direct shaft voltage value is greater than the second preset voltage threshold, wherein the first preset voltage threshold is less than the second preset voltage threshold.

[0013] In some embodiments, the controller is further configured to: when the direct-axis voltage value is between the first preset voltage threshold and the second preset voltage threshold, if the permanent magnet synchronous motor is under the first field weakening control, then control the permanent magnet synchronous motor to maintain under the first field weakening control; when the direct-axis voltage value is between the first preset voltage threshold and the second preset voltage threshold, if the permanent magnet synchronous motor is under the second field weakening control, then control the permanent magnet synchronous motor to maintain under the second field weakening control.

[0014] In some embodiments, when controlling the permanent magnet synchronous motor to switch to the first field weakening control or to remain in the first field weakening control, the controller is configured to: calculate the voltage difference between the voltage vector amplitude and the target voltage value; and adjust the excitation current value of the permanent magnet synchronous motor according to the voltage difference.

[0015] In some embodiments, when controlling the permanent magnet synchronous motor to switch to the second field weakening control or to remain in the second field weakening control, the controller is further configured to: calculate the speed difference between the actual speed and the target speed of the permanent magnet synchronous motor; and adjust the excitation current of the permanent magnet synchronous motor according to the speed difference.

[0016] In some embodiments, before obtaining the set shaft voltage value of the permanent magnet synchronous motor, the controller is further configured to perform low-pass filtering and / or averaging on the set shaft voltage value.

[0017] In some embodiments, when it is determined that the permanent magnet synchronous motor meets the field weakening control conditions, the controller is further configured to: acquire the voltage vector amplitude of the permanent magnet synchronous motor; and when the voltage vector amplitude exceeds the target voltage value, determine that the permanent magnet synchronous motor meets the field weakening control conditions.

[0018] In some embodiments, before the permanent magnet synchronous motor meets the field weakening control conditions, the controller is further configured to: acquire field weakening control parameters and bus voltage values; and determine the target voltage value based on the bus voltage value and the field weakening control parameters.

[0019] In some embodiments, when determining the target voltage value based on the bus voltage value and the field weakening control parameters, the controller is configured to: calculate the product of the bus voltage value and the field weakening control parameters, and use half of the product as the target voltage value.

[0020] In some embodiments, the home appliance includes at least one of an air conditioner, a washing machine, and a refrigerator.

[0021] To achieve the above objectives, a second aspect of the present invention provides a control method for a household appliance, the method comprising: acquiring a set shaft voltage value of a permanent magnet synchronous motor; determining whether the permanent magnet synchronous motor meets the conditions for field weakening control; and when the permanent magnet synchronous motor meets the conditions for field weakening control, controlling the permanent magnet synchronous motor to switch between a first field weakening control and a second field weakening control based on the set shaft voltage value of the permanent magnet synchronous motor and a preset voltage threshold.

[0022] According to the control method of the home appliance of the present invention, the set shaft voltage value of the permanent magnet synchronous motor is obtained, and it is determined whether the permanent magnet synchronous motor meets the field weakening control conditions. When the permanent magnet synchronous motor meets the field weakening control conditions, the permanent magnet synchronous motor is controlled to perform field weakening control. The permanent magnet synchronous motor is controlled to adaptively switch between the first field weakening control and the second field weakening control according to the relationship between the set shaft voltage value of the permanent magnet synchronous motor and the preset voltage threshold. This allows the permanent magnet synchronous motor to respond quickly within the preset voltage threshold during the first field weakening control, with good timeliness. During the second field weakening control, the permanent magnet synchronous motor can further weaken the field when the voltage threshold is exceeded, thereby increasing the speed of the permanent magnet synchronous motor and meeting the demand for higher speed.

[0023] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0024] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0025] Figure 1 This is a structural block diagram of a household appliance according to an embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram of a permanent magnet synchronous motor switching field weakening control according to an embodiment of the present invention;

[0027] Figure 3 This is a schematic diagram of a permanent magnet synchronous motor switching field weakening control according to an embodiment of the present invention;

[0028] Figure 4 This is a schematic diagram of a permanent magnet synchronous motor performing a first field weakening control according to an embodiment of the present invention;

[0029] Figure 5 This is a schematic diagram of a permanent magnet synchronous motor performing a second field weakening control according to an embodiment of the present invention;

[0030] Figure 6 This is a flowchart of a first field weakening control for a permanent magnet synchronous motor according to an embodiment of the present invention;

[0031] Figure 7 This is a flowchart of the field weakening control switching of a permanent magnet synchronous motor according to an embodiment of the present invention;

[0032] Figure 8 This is a flowchart of a control method for a household appliance according to an embodiment of the present invention.

[0033] Figure label: Household appliance 1;

[0034] Housing 11; Permanent magnet synchronous motor 12; Controller 13. Detailed Implementation

[0035] The embodiments of the present invention are described in detail below. The embodiments described with reference to the accompanying drawings are exemplary. The embodiments of the present invention are described in detail below.

[0036] The following is combined with Figures 1-7 The following is an example of a household appliance 1 according to an embodiment of the present invention.

[0037] like Figure 1 As shown, the household appliance 1 of this embodiment includes: a housing 11, a permanent magnet synchronous motor 12, and a controller 13, wherein,

[0038] The permanent magnet synchronous motor 12 is disposed inside the housing 11 and is used to control the speed of the permanent magnet synchronous motor 12 according to the DC input voltage. The controller 13 is configured to: acquire the set shaft voltage value of the permanent magnet synchronous motor 12; determine whether the permanent magnet synchronous motor 12 meets the field weakening control conditions; when the permanent magnet synchronous motor 12 meets the field weakening control conditions, control the permanent magnet synchronous motor 12 to switch between the first field weakening control and the second field weakening control according to the set shaft voltage value of the permanent magnet synchronous motor 12 and the preset voltage threshold.

[0039] Among them, the first field weakening control is shallow field weakening control, such as voltage loop field weakening control, and the second field weakening control is deep field weakening control, such as current loop field weakening control. When the permanent magnet synchronous motor 12 meets the field weakening control conditions, the permanent magnet synchronous motor 12 is controlled to adaptively switch between shallow field weakening control and deep field weakening control according to the set shaft voltage value and preset voltage threshold of the permanent magnet synchronous motor 12, thereby meeting the requirements of the permanent magnet synchronous motor 12 for speed and response speed.

[0040] In this embodiment, the controller 13 acquires the set shaft voltage value of the permanent magnet synchronous motor 12 and determines whether the permanent magnet synchronous motor 12 meets the conditions for field weakening control. For example, it determines whether the permanent magnet synchronous motor 12 meets the conditions for field weakening control based on the relationship between the voltage vector amplitude of the permanent magnet synchronous motor 12 and the target voltage value; or it determines whether the permanent magnet synchronous motor 12 meets the conditions for field weakening control based on the relationship between the ratio of the output voltage value of the permanent magnet synchronous motor 12 to the bus voltage value and the set value. The output voltage value is the quadrature axis voltage value and the direct axis voltage value.

[0041] When the permanent magnet synchronous motor 12 meets the field weakening control conditions based on the above information, the controller 13 controls the permanent magnet synchronous motor 12 to perform field weakening control. By controlling the permanent magnet synchronous motor 12 to perform field weakening control, the controller can adaptively switch between the first field weakening control and the second field weakening control according to the relationship between the set shaft voltage value and the preset voltage threshold.

[0042] For example, such as Figure 2 The diagram illustrates a field weakening control switching mechanism for a permanent magnet synchronous motor according to an embodiment of the present invention. The controller 13 controls the permanent magnet synchronous motor 12 to switch between first field weakening control and second field weakening control based on the set shaft voltage value and a preset voltage threshold of the permanent magnet synchronous motor 12. For example, when the set shaft voltage value of the permanent magnet synchronous motor 12 is less than the first preset voltage threshold, for example, V... q <V q1When it is assumed that the permanent magnet synchronous motor 12 has a higher speed requirement, the permanent magnet synchronous motor 12 is switched to the second field weakening control to ensure that the permanent magnet synchronous motor 12 can further weaken the field even when the voltage exceeds the preset threshold, thereby increasing the speed of the permanent magnet synchronous motor 12 and meeting the higher speed requirement; when the set shaft voltage value of the permanent magnet synchronous motor 12 is greater than the second preset voltage threshold, for example, V q >V q2 When the permanent magnet synchronous motor 12 is switched to the first field weakening control, the permanent magnet synchronous motor 12 performs the first field weakening control. When the permanent magnet synchronous motor 12 performs the first field weakening control, its response is fast but its timeliness is poor.

[0043] According to the present invention, the household appliance 1 acquires the set shaft voltage value of the permanent magnet synchronous motor 12 and determines whether the permanent magnet synchronous motor 12 meets the field weakening control conditions. When the permanent magnet synchronous motor 12 meets the field weakening control conditions, the permanent magnet synchronous motor 12 is controlled to perform field weakening control. Based on the relationship between the set shaft voltage value of the permanent magnet synchronous motor 12 and the preset voltage threshold, the permanent magnet synchronous motor 12 is controlled to adaptively switch between the first field weakening control and the second field weakening control. This allows the permanent magnet synchronous motor 12 to respond quickly within the preset voltage threshold during the first field weakening control, with good timeliness. During the second field weakening control, the permanent magnet synchronous motor 12 can further weaken the field even when the voltage threshold is exceeded, thereby increasing the speed of the permanent magnet synchronous motor 12 and meeting the demand for higher speeds.

[0044] In some embodiments, before the permanent magnet synchronous motor 12 switches between first field weakening control and second field weakening control according to the set shaft voltage value and preset voltage threshold of the permanent magnet synchronous motor 12, the controller 13 is further configured to control the permanent magnet synchronous motor 12 to perform the first field weakening control.

[0045] In this embodiment, before the controller 13 controls the permanent magnet synchronous motor 12 to switch between shallow field weakening control and deep field weakening control according to the set shaft voltage value and the preset voltage threshold, the controller 13 controls the permanent magnet synchronous motor 12 to perform the first field weakening control, i.e., shallow field weakening control, so that the permanent magnet synchronous motor 12 can respond quickly when low speed is required, thereby improving the timeliness of the home appliance 1.

[0046] In some embodiments, when the set shaft voltage value is the quadrature shaft voltage value, the permanent magnet synchronous motor 12 is controlled to switch between the first field weakening control and the second field weakening control according to the quadrature shaft voltage value and the preset voltage threshold. The controller 13 is configured to: control the permanent magnet synchronous motor 12 to switch to the second field weakening control or maintain the second field weakening control when the quadrature shaft voltage value is less than the first preset voltage threshold; control the permanent magnet synchronous motor 12 to switch to the first field weakening control or maintain the first field weakening control when the quadrature shaft voltage value is greater than the second preset voltage threshold, wherein the first preset voltage threshold is less than the second preset voltage threshold.

[0047] In an embodiment, such as Figure 3 The diagram shown is a schematic of a permanent magnet synchronous motor switching field weakening control according to an embodiment of the present invention. When the set shaft voltage value is the quadrature shaft voltage value, the relationship between the quadrature shaft voltage value and a preset voltage threshold is determined. If the quadrature shaft voltage value is less than a first preset voltage threshold, for example denoted as V... q1 When the permanent magnet synchronous motor 12 is switched to the second field weakening control (i.e., deep field weakening control) or maintained in the second field weakening control (i.e., deep field weakening control), it ensures that the permanent magnet synchronous motor 12 can further weaken the field even when the voltage exceeds the preset threshold, thereby increasing the speed of the permanent magnet synchronous motor 12 and meeting higher speed requirements; when the cross-axis voltage value is greater than or equal to the second preset voltage threshold, for example denoted as V... q2 When the permanent magnet synchronous motor 12 is switched to the first field weakening control (i.e., shallow field weakening control) or maintained in the first field weakening control (i.e., shallow field weakening control), the permanent magnet synchronous motor 12 can respond quickly under normal speed conditions. A first preset voltage threshold V is set. q1 Less than the second preset voltage threshold V q2 This achieves hysteresis control of a preset voltage threshold, preventing the first preset voltage threshold V from being affected. q1 Second preset voltage threshold V q2 If the difference is too small, the permanent magnet synchronous motor 12 will switch back and forth between the first field weakening control and the second field weakening control during field weakening control, resulting in the problem of unstable field weakening control. Therefore, the permanent magnet synchronous motor 12 can perform dual field weakening mode, namely shallow field weakening and deep field weakening, under different speed conditions, so as to meet the main controller's requirements for rapid changes in the speed of the permanent magnet synchronous motor 12.

[0048] In some embodiments, the controller 13 is further configured to: when the quadrature-axis voltage value is between a first preset voltage threshold and a second preset voltage threshold, if the permanent magnet synchronous motor 12 is under first field weakening control, then control the permanent magnet synchronous motor 12 to maintain under first field weakening control; when the quadrature-axis voltage value is between a first preset voltage threshold and a second preset voltage threshold, if the permanent magnet synchronous motor 12 is under second field weakening control, then control the permanent magnet synchronous motor 12 to maintain under second field weakening control.

[0049] In an embodiment, such as Figure 3The diagram shown is a schematic representation of a permanent magnet synchronous motor switching field weakening control according to an embodiment of the present invention. The quadrature-axis voltage value is set at a first preset voltage threshold V. q1 Second preset voltage threshold V q2 During this period, if the permanent magnet synchronous motor 12 is under first field weakening control (i.e., shallow field weakening control), then the controller 13 controls the permanent magnet synchronous motor 12 to maintain the first field weakening control (i.e., shallow field weakening control); the quadrature axis voltage value is at the first preset voltage threshold V. q1 Second preset voltage threshold V q2 If the permanent magnet synchronous motor 12 is in the second field weakening mode (i.e., deep field weakening control), then the permanent magnet synchronous motor 12 is controlled to remain in the second field weakening mode (i.e., deep field weakening control). This further reduces the problem of unstable field weakening control caused by the permanent magnet synchronous motor 12 switching back and forth between the first field weakening control and the second field weakening control. This allows the permanent magnet synchronous motor 12 to adaptively and stably switch between dual field weakening modes (i.e., shallow field weakening and deep field weakening) under different speed conditions, meeting the main controller's requirements for rapid changes in the speed of the permanent magnet synchronous motor 12. In some embodiments, when the shaft voltage value is set to the direct shaft voltage value, the permanent magnet synchronous motor 12 is controlled to switch between the first field weakening control and the second field weakening control according to the direct shaft voltage value and a preset voltage threshold. The controller 13 is configured to: control the permanent magnet synchronous motor 12 to switch to the second field weakening control or remain in the second field weakening control when the absolute value of the direct shaft voltage value is less than the first preset voltage threshold; and control the permanent magnet synchronous motor 12 to switch to the first field weakening control or remain in the first field weakening control when the absolute value of the direct shaft voltage value is greater than the second preset voltage threshold, wherein the first preset voltage threshold is less than the second preset voltage threshold.

[0050] In this embodiment, when the axis voltage value is set to the direct axis voltage value, the relationship between the direct axis voltage value and a preset voltage threshold is determined. If the absolute value of the direct axis voltage value is less than a first preset voltage threshold V, the value is determined to be within the range of the direct axis voltage value. q1 When the permanent magnet synchronous motor 12 is switched to the second field weakening control (i.e., deep field weakening control) or maintained in the second field weakening control (i.e., deep field weakening control), it ensures that the permanent magnet synchronous motor 12 can further weaken the field even when the voltage exceeds the preset threshold, thereby increasing the speed of the permanent magnet synchronous motor 12 and meeting higher speed requirements; when the absolute value of the direct axis voltage is greater than the second preset voltage threshold V q2 When the permanent magnet synchronous motor 12 is switched to the first field weakening control (i.e., shallow field weakening control) or maintained in the first field weakening control (i.e., shallow field weakening control), the permanent magnet synchronous motor 12 can respond quickly under normal speed conditions. A first preset voltage threshold V is set. q1 Less than the second preset voltage threshold V q2 This achieves hysteresis control of a preset voltage threshold, preventing the first preset voltage threshold V from being affected. q1 Second preset voltage threshold V q2If the difference is too small, the permanent magnet synchronous motor 12 will switch back and forth between the first field weakening control and the second field weakening control during field weakening control, resulting in the problem of unstable field weakening control. Therefore, the permanent magnet synchronous motor 12 can perform dual field weakening mode, namely shallow field weakening and deep field weakening, under different speed conditions, so as to meet the main controller's requirements for rapid changes in the speed of the permanent magnet synchronous motor 12.

[0051] In some embodiments, the controller 13 is further configured to: when the direct-axis voltage value is between a first preset voltage threshold and a second preset voltage threshold, if the permanent magnet synchronous motor 12 is under first field weakening control, then control the permanent magnet synchronous motor 12 to maintain under first field weakening control; when the direct-axis voltage value is between the first preset voltage threshold and the second preset voltage threshold, if the permanent magnet synchronous motor 12 is under second field weakening control, then control the permanent magnet synchronous motor 12 to maintain under second field weakening control.

[0052] In this embodiment, the direct-axis voltage value is at a first preset voltage threshold V. q1 Second preset voltage threshold V q2 During this period, if the permanent magnet synchronous motor 12 is under first field weakening control (i.e., shallow field weakening control), then the controller 13 controls the permanent magnet synchronous motor 12 to maintain the first field weakening control (i.e., shallow field weakening control); the direct-axis voltage value is at the first preset voltage threshold V. q1 Second preset voltage threshold V q2 If the permanent magnet synchronous motor 12 is in the second field weakening mode, i.e., deep field weakening control, then the permanent magnet synchronous motor 12 is controlled to maintain the second field weakening mode, i.e., deep field weakening control. This further reduces the problem of the permanent magnet synchronous motor 12 switching back and forth between the first field weakening control and the second field weakening control, which leads to the instability of field weakening control. This allows the permanent magnet synchronous motor 12 to perform adaptive and stable switching between dual field weakening modes, i.e., shallow field weakening and deep field weakening, under different speed conditions, so as to meet the main controller's requirements for rapid changes in the speed of the permanent magnet synchronous motor 12.

[0053] In some embodiments, when the permanent magnet synchronous motor 12 is switched to the first field weakening control or maintained in the first field weakening control, the controller 13 is configured to: calculate the voltage difference between the voltage vector magnitude and the target voltage value; and adjust the excitation current value of the permanent magnet synchronous motor 12 according to the voltage difference.

[0054] In an embodiment, such as Figure 4 The diagram shown illustrates a first field weakening control of a permanent magnet synchronous motor according to an embodiment of the present invention. Taking voltage loop field weakening as an example, when the controller 13 controls the permanent magnet synchronous motor 12 to switch to the first field weakening (i.e., shallow field weakening control) or maintain the first field weakening (i.e., shallow field weakening control), it calculates the voltage difference between the voltage vector amplitude and the target voltage value, and adjusts the motor according to the voltage difference. The direct-axis voltage is, for example, denoted as V. d * And the quadrature-axis voltage, for example, denoted as V q* And calculate the direct-axis voltage V. d * and quadrature axis voltage V q * The root mean square (RMS) is used as the magnitude of the voltage vector, for example, denoted as V. s That is, voltage vector magnitude V s The calculation formula is as follows:

[0055]

[0056] Determine the voltage vector magnitude V s Then, calculate the voltage vector magnitude V. s The voltage difference from the target voltage value is used to adjust the excitation current I of the permanent magnet synchronous motor 12 via a PI (proportional-integral) controller or an integral controller. d * This controls the voltage vector amplitude V. s Within the limits of the bus voltage tolerance, ensure the normal operation of the permanent magnet synchronous motor 12.

[0057] In some embodiments, when the permanent magnet synchronous motor 12 is switched to the second field weakening control or maintained in the second field weakening control, the controller 13 is further configured to: calculate the speed difference between the actual speed and the target speed of the permanent magnet synchronous motor 12; and adjust the excitation current of the permanent magnet synchronous motor 12 according to the speed difference.

[0058] In an embodiment, such as Figure 5 The diagram shown illustrates a second field weakening control of a permanent magnet synchronous motor according to an embodiment of the present invention. Taking single-current-loop field weakening as an example, when the controller 13 controls the permanent magnet synchronous motor 12 to switch to or maintain the second field weakening control, the actual rotational speed ω is calculated. Λ With the target rotational speed ω * The speed difference is used to control the excitation current of the permanent magnet synchronous motor 12. Specifically, the current command after torque conversion from the speed loop is used as the excitation current command for the permanent magnet synchronous motor 12, and the excitation current value I is adjusted accordingly. d * The adjustment. The torque current, for example, is denoted as I. q * And the excitation current, for example, denoted as I d * Torque current I q * and excitation current I d * The root mean square (RMS) is used as the phase current limiting amplitude, for example, denoted as I. slim * That is, the phase current limiting amplitude Islim * The calculation formula is as follows:

[0059]

[0060] Therefore, the torque current I q * By current limiting value I slim * and excitation current I d * It changes with the change of excitation current I d * Adjust according to changes.

[0061] Obtain the excitation current I d * and torque current I q * Then, based on the excitation current I d * and I d Perform PI control and adjust according to the torque current I. q * and I q PI control is performed, followed by decoupling control. After decoupling control, the corresponding quadrature-axis voltage value and direct-axis voltage value are obtained. By changing the angle of the quadrature-axis voltage value and direct-axis voltage value, the voltage value at the corresponding coordinate angle is obtained. The three-phase voltage is obtained by changing the above voltage values ​​accordingly, and the motor is controlled accordingly based on the above three-phase output voltage.

[0062] In some embodiments, before acquiring the set shaft voltage value of the permanent magnet synchronous motor 12, the controller 13 is further configured to perform low-pass filtering and / or averaging on the set shaft voltage value.

[0063] In an embodiment, such as Figure 2 As shown, before obtaining the set shaft voltage value of the permanent magnet synchronous motor 12, the controller 13 performs low-pass filtering and / or averaging processing on the obtained set shaft voltage value to obtain the processed actual speed, for example, denoted as V. qmean This is to ensure the stability of the obtained set shaft voltage value.

[0064] In some embodiments, when it is determined that the permanent magnet synchronous motor 12 meets the field weakening control conditions, the controller 13 is further configured to: acquire the voltage vector amplitude of the permanent magnet synchronous motor 12; and determine that the permanent magnet synchronous motor 12 meets the field weakening control conditions when the voltage vector amplitude exceeds the target voltage value.

[0065] In this embodiment, the controller 13 acquires the voltage vector amplitude of the permanent magnet synchronous motor 12, determines the relationship between the voltage vector amplitude and the target voltage value, and considers that the voltage vector amplitude of the permanent magnet synchronous motor 12 exceeds the bus voltage value when the voltage vector amplitude exceeds the target voltage value, that is, exceeds the modulation limit range that the bus voltage can withstand, and determines that the permanent magnet synchronous motor 12 meets the field weakening control conditions.

[0066] In some embodiments, before the permanent magnet synchronous motor 12 meets the field weakening control conditions, the controller 13 is further configured to: acquire field weakening control parameters and bus voltage values; and determine a target voltage value based on the bus voltage values ​​and field weakening control parameters.

[0067] In an embodiment, such as Figure 4 The diagram shown illustrates the first field weakening control of a permanent magnet synchronous motor according to an embodiment of the present invention. Before the permanent magnet synchronous motor 12 meets the field weakening control conditions, the controller 13 acquires field weakening control parameters, for example, denoted as K. fw And the bus voltage value, for example, denoted as V dc So as to control the field weakening parameter K fw and bus voltage value V dc Determine the target voltage value.

[0068] In some embodiments, when determining the target voltage value based on the bus voltage value and the field weakening control parameters, the controller 13 is configured to: calculate the product of the bus voltage value and the field weakening control parameters, and use half of the product as the target voltage value.

[0069] In an embodiment, such as Figure 4 The diagram shown illustrates the first field weakening control of a permanent magnet synchronous motor according to an embodiment of the present invention. The controller 13 acquires the field weakening control parameter K. fw and bus voltage value V dc Then, calculate the bus voltage value V. dc With field weakening control parameter K fw The product of V and V is used, and half of the product is taken as the target voltage value. Therefore, the formula for calculating the target voltage value is: V dc ×K fw / 2, in order to determine the modulation limit range that the bus voltage can withstand.

[0070] The following is for reference. Figure 6 This invention describes a method for performing first field weakening control on a permanent magnet synchronous motor according to an embodiment of the present invention.

[0071] like Figure 6 As shown, the method for performing first field weakening control on a permanent magnet synchronous motor according to an embodiment of the present invention includes at least steps S11-S13.

[0072] Step S11: Obtain the field weakening control parameters and bus voltage values.

[0073] Step S12: Calculate the product of the bus voltage value and the field weakening control parameter, and take half of the product as the target voltage value.

[0074] Step S13: Calculate the voltage difference between the voltage vector amplitude and the target voltage value, and adjust the excitation current value of the permanent magnet synchronous motor according to the voltage difference.

[0075] The following is for reference. Figure 7 This invention describes a method for switching field weakening control of a permanent magnet synchronous motor according to an embodiment of the present invention.

[0076] like Figure 7 As shown, the method for switching field weakening control of a permanent magnet synchronous motor according to an embodiment of the present invention includes at least steps S31-S45.

[0077] Step S31: Control the permanent magnet synchronous motor to perform the first field weakening control, perform low-pass filtering and / or averaging processing on the set shaft voltage value, and obtain the set shaft voltage value of the permanent magnet synchronous motor.

[0078] Step S32: Obtain the field weakening control parameters and bus voltage values.

[0079] Step S33: Calculate the product of the bus voltage value and the field weakening control parameter, and take half of the product as the target voltage value.

[0080] Step S34: Determine whether the permanent magnet synchronous motor meets the field weakening control conditions. If yes, proceed to step S35; otherwise, proceed to step S31.

[0081] Step S35: Determine whether the absolute value of the quadrature-axis voltage value or the direct-axis voltage value is less than the first preset voltage threshold. If yes, proceed to step S36; otherwise, proceed to step S38.

[0082] Step S36: Control the permanent magnet synchronous motor to switch to the second field weakening control or maintain the second field weakening control.

[0083] Step S37: Calculate the voltage difference between the voltage vector amplitude and the target voltage value, and adjust the excitation current value of the permanent magnet synchronous motor according to the voltage difference.

[0084] Step S38: Determine whether the absolute value of the quadrature-axis voltage value or the direct-axis voltage value is less than the second preset voltage threshold. If yes, proceed to step S39; otherwise, proceed to step S43.

[0085] Step S39: Determine whether the permanent magnet synchronous motor is under first field weakening control. If yes, proceed to step S40; otherwise, proceed to step S41.

[0086] Step S40: Control the permanent magnet synchronous motor to maintain the first field weakening control.

[0087] Step S41: Determine whether the permanent magnet synchronous motor is under second field weakening control. If yes, proceed to step S42; otherwise, proceed to step S40.

[0088] Step S42: Control the permanent magnet synchronous motor to maintain the second field weakening control.

[0089] Step S43: Determine whether the absolute value of the quadrature-axis voltage value or the direct-axis voltage value is greater than the second preset voltage threshold. If yes, proceed to step S44; otherwise, proceed to step S34.

[0090] Step S44: Control the permanent magnet synchronous motor to switch to the first field weakening control or maintain the first field weakening control.

[0091] Step S45: Calculate the speed difference between the actual speed and the target speed, and adjust the excitation current of the permanent magnet synchronous motor according to the speed difference.

[0092] According to an embodiment of the present invention, the household appliance 1,

[0093] The following is for reference. Figure 8 This invention describes a method for controlling home appliances according to an embodiment of the invention.

[0094] like Figure 8 As shown, the control method for home appliances in this embodiment of the invention includes at least steps S1-S3.

[0095] Step S1: Obtain the set shaft voltage value of the permanent magnet synchronous motor.

[0096] In this embodiment, the controller acquires the set shaft voltage value of the permanent magnet synchronous motor.

[0097] Step S2: Determine whether the permanent magnet synchronous motor meets the conditions for field weakening control.

[0098] In this embodiment, it is determined whether the permanent magnet synchronous motor meets the field weakening control conditions. For example, it is determined whether the permanent magnet synchronous motor meets the field weakening control conditions based on the relationship between the voltage vector amplitude of the permanent magnet synchronous motor and the target voltage value; or it is determined whether the permanent magnet synchronous motor meets the field weakening control conditions based on the relationship between the ratio of the output voltage value of the permanent magnet synchronous motor to the bus voltage value and the set value. The output voltage value is the quadrature axis voltage value and the direct axis voltage value.

[0099] Step S3: When the permanent magnet synchronous motor meets the field weakening control conditions, the permanent magnet synchronous motor is controlled to switch between the first field weakening control and the second field weakening control according to the set shaft voltage value and the preset voltage threshold of the permanent magnet synchronous motor.

[0100] In this embodiment, when it is determined that the permanent magnet synchronous motor meets the conditions for field weakening control, the permanent magnet synchronous motor is controlled to perform field weakening control. By controlling the permanent magnet synchronous motor to perform field weakening control, the permanent magnet synchronous motor can be adaptively switched between the first field weakening control and the second field weakening control according to the relationship between the set shaft voltage value and the preset voltage threshold.

[0101] For example, such as Figure 2 The diagram shown illustrates the switching field weakening control of a permanent magnet synchronous motor according to an embodiment of the present invention. The controller controls the permanent magnet synchronous motor to switch between first field weakening control and second field weakening control based on the set shaft voltage value and a preset voltage threshold. For example, when the set shaft voltage value of the permanent magnet synchronous motor is less than the first preset voltage threshold, such as V... q <V q1 When a higher speed requirement is considered for the permanent magnet synchronous motor (PMSM), the control switches to the second field weakening control. This ensures that the PMSM can further weaken the field even when the voltage exceeds a preset threshold, thereby increasing the PMSM's speed and meeting the higher speed requirement. When the set shaft voltage value of the PMSM exceeds the second preset voltage threshold, for example, V... q >V q2 When the permanent magnet synchronous motor is switched to the first field weakening control, the permanent magnet synchronous motor performs the first field weakening control. When the permanent magnet synchronous motor performs the first field weakening control, its response is fast, but its timeliness is poor.

[0102] According to the control method of the home appliance of the present invention, the set shaft voltage value of the permanent magnet synchronous motor is obtained, and it is determined whether the permanent magnet synchronous motor meets the field weakening control conditions. When the permanent magnet synchronous motor meets the field weakening control conditions, the permanent magnet synchronous motor is controlled to perform field weakening control. The permanent magnet synchronous motor is controlled to adaptively switch between the first field weakening control and the second field weakening control according to the relationship between the set shaft voltage value of the permanent magnet synchronous motor and the preset voltage threshold. This allows the permanent magnet synchronous motor to respond quickly within the preset voltage threshold during the first field weakening control, with good timeliness. During the second field weakening control, the permanent magnet synchronous motor can further weaken the field when the voltage threshold is exceeded, thereby increasing the speed of the permanent magnet synchronous motor and meeting the demand for higher speed.

[0103] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example.

[0104] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A household appliance, characterized in that, include: case; A permanent magnet synchronous motor is installed inside the housing and is used to control the speed of the permanent magnet synchronous motor according to the DC input voltage; The controller is configured to acquire a set shaft voltage value of the permanent magnet synchronous motor; Determine whether the permanent magnet synchronous motor meets the conditions for field weakening control; When the permanent magnet synchronous motor meets the field weakening control conditions, the controller switches between first field weakening control and second field weakening control based on the set shaft voltage value and preset voltage threshold of the permanent magnet synchronous motor. When controlling the permanent magnet synchronous motor to switch to second field weakening control or maintain in second field weakening control, the controller is further configured to: Calculate the speed difference between the actual speed and the target speed of the permanent magnet synchronous motor; The excitation current command of the permanent magnet synchronous motor is adjusted according to the speed difference. The torque current command changes with the current limit value and the excitation current command, and is adjusted as the excitation current command changes.

2. The household appliance according to claim 1, characterized in that, Before switching between first field weakening control and second field weakening control based on the set shaft voltage value and preset voltage threshold of the permanent magnet synchronous motor, the controller is further configured to: The permanent magnet synchronous motor is controlled to perform the first field weakening control.

3. The household appliance according to claim 1 or 2, characterized in that, When the set shaft voltage value is the quadrature shaft voltage value, the permanent magnet synchronous motor is controlled to switch between first field weakening control and second field weakening control based on the quadrature shaft voltage value and a preset voltage threshold. The controller is configured to: When the cross-axis voltage value is less than the first preset voltage threshold, the permanent magnet synchronous motor is controlled to switch to the second field weakening control or remain in the second field weakening control. When the cross-axis voltage value is greater than the second preset voltage threshold, the permanent magnet synchronous motor is controlled to switch to the first field weakening control or remain in the first field weakening control, wherein the first preset voltage threshold is less than the second preset voltage threshold.

4. The household appliance according to claim 3, characterized in that, The controller is also configured to: When the cross-axis voltage value is between the first preset voltage threshold and the second preset voltage threshold, if the permanent magnet synchronous motor is under the first field weakening control, then the permanent magnet synchronous motor is controlled to remain under the first field weakening control. When the cross-axis voltage value is between the first preset voltage threshold and the second preset voltage threshold, if the permanent magnet synchronous motor is under the second field weakening control, then the permanent magnet synchronous motor is controlled to remain under the second field weakening control.

5. The household appliance according to claim 2, characterized in that, When the set shaft voltage value is the direct shaft voltage value, the permanent magnet synchronous motor is controlled to switch between first field weakening control and second field weakening control based on the direct shaft voltage value and a preset voltage threshold. The controller is configured to: When the absolute value of the direct-axis voltage is less than the first preset voltage threshold, the permanent magnet synchronous motor is controlled to switch to the second field weakening control or remain in the second field weakening control. When the absolute value of the direct-axis voltage is greater than the second preset voltage threshold, the permanent magnet synchronous motor is controlled to switch to the first field weakening control or remain in the first field weakening control, wherein the first preset voltage threshold is less than the second preset voltage threshold.

6. The household appliance according to claim 5, characterized in that, The controller is also configured to: When the direct-axis voltage value is between the first preset voltage threshold and the second preset voltage threshold, if the permanent magnet synchronous motor is under the first field weakening control, then the permanent magnet synchronous motor is controlled to remain under the first field weakening control. When the direct-axis voltage value is between the first preset voltage threshold and the second preset voltage threshold, if the permanent magnet synchronous motor is under the second field weakening control, then the permanent magnet synchronous motor is controlled to remain under the second field weakening control.

7. The household appliance according to claim 3, characterized in that, When controlling the permanent magnet synchronous motor to switch to the first field weakening control or maintain in the first field weakening control, the controller is configured to: Calculate the voltage difference between the voltage vector magnitude and the target voltage value; The excitation current value of the permanent magnet synchronous motor is adjusted according to the voltage difference.

8. The household appliance according to claim 1, characterized in that, Before obtaining the set shaft voltage value of the permanent magnet synchronous motor, the controller is further configured to: The set shaft voltage value is subjected to low-pass filtering and / or averaging.

9. The household appliance according to claim 1, characterized in that, Before the permanent magnet synchronous motor meets the field weakening control conditions, the controller is further configured to: Obtain the field weakening control parameters and bus voltage values; The target voltage value is determined based on the bus voltage value and the field weakening control parameters.

10. A method for controlling a household appliance, characterized in that, include: Obtain the set shaft voltage value of the permanent magnet synchronous motor; Determine whether the permanent magnet synchronous motor meets the conditions for field weakening control; When the permanent magnet synchronous motor meets the field weakening control conditions, the permanent magnet synchronous motor is controlled to switch between first field weakening control and second field weakening control according to the set shaft voltage value and preset voltage threshold of the permanent magnet synchronous motor. Specifically, when controlling the permanent magnet synchronous motor to switch to second field weakening control or maintain in second field weakening control: Calculate the speed difference between the actual speed and the target speed of the permanent magnet synchronous motor; The excitation current command of the permanent magnet synchronous motor is adjusted according to the speed difference. The torque current command changes with the current limit value and the excitation current command, and is adjusted as the excitation current command changes.

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