Household appliance and control method thereof

Abstract

The invention discloses a household appliance and a control method thereof, the household appliance comprises a shell, a permanent magnet synchronous motor and a controller, and the controller is configured to inject a high-frequency square wave voltage signal on a dr axis of an assumed coordinate system and obtain a three-phase current signal of the permanent magnet synchronous motor every N carrier wave periods; in the kNth carrier period, determining an included angle between the assumed coordinate system and the rotating coordinate system according to the three-phase current signals corresponding to the current carrier period and the (k-1) Nth carrier period; according to the included angle between the assumed coordinate system and the rotating coordinate system, the real rotor position of the permanent magnet synchronous motor is determined, so that the data updating frequency of the high-frequency square wave injection method is improved from the original frequency of injected high-frequency square wave voltage signals to N frequency division of the carrier frequency, and the estimation speed and the angle updating speed of the motor can be greatly improved; therefore, the response speed of the motor is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of motors, and in particular to a household appliance and a control method thereof. Background Art

[0002] When controlling a permanent magnet synchronous motor without a position sensor, a special algorithm is required to estimate the rotor position. In the medium and high speed operation stage, the rotor position is generally estimated by observing the back electromotive force, and in the zero speed and low speed stages, the rotor position is generally estimated by the high-frequency injection method. The industry has developed technologies for injecting sine waves in a stationary coordinate system, injecting sine waves in a rotating coordinate system, and injecting square waves in a rotating coordinate system. However, the above traditional high-frequency signal injection method has a slow response speed when determining the true rotor position of the permanent magnet synchronous motor, and when the frequency of the injected signal changes, the phase-locked loop design is more complicated. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the purpose of the present invention is to provide a household appliance and a control method thereof.

[0004] The present invention provides a household appliance, which comprises: a housing; a permanent magnet synchronous motor, which is arranged in the housing and is used to operate according to a DC input voltage; and a controller, which is configured to: r A high-frequency square wave voltage signal is injected into the axis, and the three-phase current signal of the permanent magnet synchronous motor is obtained every N carrier cycles; in the kNth carrier cycle, the angle between the assumed coordinate system and the rotating coordinate system is determined according to the three-phase current signal corresponding to the current carrier cycle and the (k-1)Nth carrier cycle; wherein N is a positive integer, and k is a positive integer greater than 1; according to the angle between the assumed coordinate system and the rotating coordinate system, the real rotor position of the permanent magnet synchronous motor is determined.

[0005] In addition, the household appliance according to the embodiment of the present invention may also have the following additional technical features:

[0006] Further, when determining the angle between the assumed coordinate system and the rotating coordinate system according to the three-phase current signal corresponding to the current carrier cycle and the (k-1)Nth carrier cycle, the controller is configured to: determine, according to the three-phase current signal corresponding to the current carrier cycle, the q corresponding to the current carrier cycle in the assumed coordinate system r The response current signal of the axis; and, according to the three-phase current signal corresponding to the (k-1)Nth carrier cycle, determining the q corresponding to the (k-1)Nth carrier cycle in the assumed coordinate system. r The response current signal of the axis; according to the q corresponding to the current carrier cycle rThe response current signal of the axis and the q corresponding to the (k-1)Nth carrier cycle r The response current signal of the shaft determines the angle between the assumed coordinate system and the rotating coordinate system.

[0007] Further, according to the three-phase current signal corresponding to the current carrier cycle, the q corresponding to the current carrier cycle in the assumed coordinate system is determined. r When the response current signal of the axis is obtained, the controller is configured to: obtain the q corresponding to the current carrier cycle by Clark transformation and Park transformation of the three-phase current signal corresponding to the current carrier cycle r The response current signal of the axis.

[0008] Further, according to the three-phase current signal corresponding to the (k-1)Nth carrier cycle, the q corresponding to the (k-1)Nth carrier cycle in the assumed coordinate system is determined. r When the response current signal of the axis is obtained, the controller is configured to: perform Clark transformation and Park transformation on the three-phase current signal corresponding to the (k-1)Nth carrier cycle to obtain the q corresponding to the (k-1)Nth carrier cycle r The response current signal of the axis.

[0009] Further, according to the q corresponding to the current carrier cycle r The response current signal of the axis and the q corresponding to the (k-1)Nth carrier cycle r When the angle between the assumed coordinate system and the rotating coordinate system is determined based on the response current signal of the axis, the controller is configured to perform the following calculation:

[0010]

[0011]

[0012]

[0013] Among them, θ err is the angle between the assumed coordinate system and the rotated coordinate system, I q[jN] is the q corresponding to the current carrier period r The response current of the shaft, I q[(k-1)N] is the q corresponding to the (k-1)Nth carrier period r The response current of the axis, T is the carrier period, u dh is the d of the permanent magnet synchronous motor after the high frequency square wave voltage signal is injected r Shaft voltage, L d , L q are the d-axis inductance and q-axis inductance of the permanent magnet synchronous motor respectively, and N is a positive integer.

[0014] Further, the controller is configured to execute the following formula:

[0015] When u dh >0,

[0016] When u dh <0,

[0017] Furthermore, when determining the true rotor position of the permanent magnet synchronous motor based on the angle between the assumed coordinate system and the rotating coordinate system, the controller is configured to: use a phase-locked loop to adjust the angle between the assumed coordinate system and the rotating coordinate system; when the angle between the assumed coordinate system and the rotating coordinate system is zero, obtain the true rotor position of the permanent magnet synchronous motor.

[0018] Furthermore, the d-axis direction of the rotating coordinate system is the N-pole direction of the permanent magnet rotor in the permanent magnet synchronous motor, and the q-axis direction of the rotating coordinate system is the direction of rotating the d-axis direction counterclockwise by 90°.

[0019] Further, according to the three-phase current signal corresponding to the current carrier cycle, the q corresponding to the current carrier cycle in the assumed coordinate system is determined. r After the response current signal of the shaft is received, the controller is further configured to: extract the current low-frequency component after the three-phase current signal corresponding to the current carrier cycle undergoes the Clark transformation and the Park transformation to control the normal operation of the permanent magnet synchronous motor.

[0020] According to an embodiment of the present invention, the household appliance comprises: a housing, a permanent magnet synchronous motor and a controller. The permanent magnet synchronous motor is arranged in the housing and is used to operate according to a DC input voltage; the controller is configured to: rA high-frequency square wave voltage signal is injected into the axis, and the three-phase current signal of the permanent magnet synchronous motor is obtained every N carrier cycles. In the kNth carrier cycle, the angle between the assumed coordinate system and the rotating coordinate system is determined according to the three-phase current signal corresponding to the current carrier cycle and the (k-1)Nth carrier cycle, wherein N is a positive integer and k is a positive integer greater than 1. According to the angle between the assumed coordinate system and the rotating coordinate system, the real rotor position of the permanent magnet synchronous motor is determined, so that the data update frequency of the high-frequency square wave injection method is increased from the original frequency of the injected high-frequency square wave voltage signal to the N-frequency division of the carrier frequency, that is, no matter how much the period of the injected high-frequency square wave voltage signal is, the angle between the assumed coordinate system and the rotating coordinate system is calculated according to the carrier cycle / N, which can greatly improve the update speed of the motor estimated speed and angle, thereby improving the response speed of the motor. Furthermore, when using a phase-locked loop to adjust the angle between the assumed coordinate system and the rotating coordinate system, the gain coefficient is made independent of the frequency of the injected high-frequency square wave signal. When the d r When the frequency of the high-frequency square wave voltage signal on the axis is not fixed, the design of the phase-locked loop can be simplified.

[0021] In view of the above problems, the present invention further proposes a control method for household appliances, comprising: assuming that the coordinate system d r A high-frequency square wave voltage signal is injected into the axis, and the three-phase current signal of the permanent magnet synchronous motor is obtained every N carrier cycles; in the kNth carrier cycle, the angle between the assumed coordinate system and the rotating coordinate system is determined according to the three-phase current signal corresponding to the current carrier cycle and the (k-1)Nth carrier cycle; wherein N is a positive integer, and k is a positive integer greater than 1; according to the angle between the assumed coordinate system and the rotating coordinate system, the real rotor position of the permanent magnet synchronous motor is determined.

[0022] According to the control method of the household appliance of the embodiment of the present invention, by assuming the coordinate system d rA high-frequency square wave voltage signal is injected into the axis, and the three-phase current signal of the permanent magnet synchronous motor is obtained every N carrier cycles. In the kNth carrier cycle, the angle between the assumed coordinate system and the rotating coordinate system is determined according to the three-phase current signal corresponding to the current carrier cycle and the (k-1)Nth carrier cycle, wherein N is a positive integer and k is a positive integer greater than 1. According to the angle between the assumed coordinate system and the rotating coordinate system, the real rotor position of the permanent magnet synchronous motor is determined, so that the data update frequency of the high-frequency square wave injection method is increased from the original frequency of the injected high-frequency square wave voltage signal to the N-frequency division of the carrier frequency, that is, no matter how much the period of the injected high-frequency square wave voltage signal is, the angle between the assumed coordinate system and the rotating coordinate system is calculated according to the carrier cycle / N, which can greatly improve the update speed of the motor estimated speed and angle, thereby improving the response speed of the motor. Furthermore, when using a phase-locked loop to adjust the angle between the assumed coordinate system and the rotating coordinate system, the gain coefficient is made independent of the frequency of the injected high-frequency square wave signal. When the d r When the frequency of the high-frequency square wave voltage signal on the axis is not fixed, the design of the phase-locked loop can be simplified.

[0023] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0026] Figure 2 is a schematic diagram of an assumed coordinate system and a rotated coordinate system according to an embodiment of the present invention;

[0027] Figure 3 is a principle block diagram of position sensorless control of a permanent magnet synchronous motor based on high frequency square wave injection according to an embodiment of the present invention;

[0028] Figure 4 is a flow chart of determining the angle between the assumed coordinate system and the rotated coordinate system according to one embodiment of the present invention;

[0029] Figure 5 is a waveform diagram of position sensorless control of a permanent magnet synchronous motor based on high-frequency square wave signal injection according to an embodiment of the present invention;

[0030] Figure 6 is a flow chart of obtaining the real rotor position of a permanent magnet synchronous motor according to one embodiment of the present invention;

[0031] Figure 7 is a flow chart of a method for controlling a household appliance according to an embodiment of the present invention. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] In the description of the present invention, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0034] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0035] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] Reference below Figure 1-Figure 7 A home appliance and a control method thereof according to an embodiment of the present invention are described.

[0037] Figure 1 Schematic diagram of the structure of a household appliance according to an embodiment of the present invention. Figure 1As shown, a household appliance comprises: a housing 10, a permanent magnet synchronous motor 20 and a controller 30. The permanent magnet synchronous motor 20 is arranged in the housing 10 and is used to operate according to a DC input voltage; the controller 30 is configured to: assume a coordinate system d r A high-frequency square wave voltage signal is injected into the axis, and the three-phase current signal of the permanent magnet synchronous motor 20 is obtained every N carrier cycles; in the kNth carrier cycle, the angle between the assumed coordinate system and the rotating coordinate system is determined according to the three-phase current signal corresponding to the current carrier cycle and the (k-1)Nth carrier cycle; wherein N is a positive integer, and k is a positive integer greater than 1; according to the angle between the assumed coordinate system and the rotating coordinate system, the actual rotor position of the permanent magnet synchronous motor 20 is determined.

[0038] Specifically, if Figure 2 As shown, assuming the coordinate system is d r q r Coordinate system, the rotating coordinate system is the dq coordinate system, assuming that the angle between the coordinate system and the rotating coordinate system is θ err The mathematical model of the permanent magnet synchronous motor 20 is as follows:

[0039]

[0040]

[0041] Among them, u d is the d-axis voltage of the permanent magnet synchronous motor 20, u q The q-axis voltage of the permanent magnet synchronous motor 20, R is the phase resistance of the permanent magnet synchronous motor 20, I d is the d-axis current of the permanent magnet synchronous motor 20, I q is the q-axis current of the permanent magnet synchronous motor 20, L d is the d-axis inductance of the permanent magnet synchronous motor 20, L q is the q-axis inductance of the permanent magnet synchronous motor 20, ω is the electrical angular velocity of the permanent magnet synchronous motor 20, ψ f is the magnetic flux of the permanent magnet synchronous motor 20.

[0042] When a high-frequency square wave signal is injected into the low-speed stage of the permanent magnet synchronous motor 20, the speed term and the resistance term in the above equation can be ignored and simplified to:

[0043]

[0044]

[0045] Among them, u dh is the d-axis voltage of the permanent magnet synchronous motor 20 after the high-frequency square wave signal is injected, u qhis the q-axis voltage of the permanent magnet synchronous motor 20 after the high-frequency square wave signal is injected, L d is the d-axis inductance of the permanent magnet synchronous motor 20, L q is the q-axis inductance of the permanent magnet synchronous motor 20, I dh is the d-axis current of the permanent magnet synchronous motor 20 after the high-frequency square wave signal is injected, I qh It is the q-axis current of the permanent magnet synchronous motor 20 after the high-frequency square wave signal is injected.

[0046] Then transform the above equation from the rotated coordinate system to the assumed coordinate system, and we can get:

[0047]

[0048]

[0049]

[0050]

[0051] Among them, I dh is the d-axis current of the permanent magnet synchronous motor 20 after the high-frequency square wave signal is injected, I qh is the q-axis current of the permanent magnet synchronous motor 20 after the high-frequency square wave signal is injected, θ err is the angle between the assumed coordinate system and the rotated coordinate system, u dh is the d-axis voltage of the permanent magnet synchronous motor 20 after the high-frequency square wave signal is injected, u qh is the q-axis voltage of the permanent magnet synchronous motor 20 after the high-frequency square wave signal is injected, L d is the d-axis inductance of the permanent magnet synchronous motor 20, L q is the q-axis inductance of the permanent magnet synchronous motor 20.

[0052] Without installing the rotor position sensor and without performing rotor position locking, the rotor position angle θ r is unknown, here we can first estimate the rotor position angle by assuming a coordinate system: In this way, the relationship between the assumed coordinate system and the rotating coordinate system is established. err When it approaches 0, the real rotor position of the permanent magnet synchronous motor 20 can be obtained.

[0053] Specifically, according to the angle θ between the assumed coordinate system and the rotated coordinate system err , determining the true rotor position of the permanent magnet synchronous motor 20, including: using a phase-locked loop to adjust the angle between the assumed coordinate system and the rotating coordinate system; when the angle θ between the assumed coordinate system and the rotating coordinate system err When is zero, the real rotor position of the permanent magnet synchronous motor 20 is obtained. Figure 3 As shown in the figure, after extracting the angle error, the angle error θ between the assumed coordinate system and the rotating coordinate system is adjusted in real time through the phase-locking technology. err , so that the difference between its position angle and the rotation coordinate system is θ err =0, thereby achieving real-time tracking of the assumed coordinate system and the rotating coordinate system, so that the position information of the permanent magnet synchronous motor 20 in the rotating coordinate system can be obtained without measuring through a rotor position sensor.

[0054] In the embodiment of the present invention, the coordinate system d is assumed to be r After the high-frequency square wave voltage signal is injected into the shaft, the three-phase current signal of the permanent magnet synchronous motor 20 is obtained every N carrier cycles, and the angle between the assumed coordinate system and the rotating coordinate system is determined according to the three-phase current signal of the permanent magnet synchronous motor 20, so as to determine the real rotor position of the permanent magnet synchronous motor 20 according to the angle between the assumed coordinate system and the rotating coordinate system. In this way, when determining the real rotor position of the permanent magnet synchronous motor 20, the angle between the assumed coordinate system and the rotating coordinate system is calculated once every N carrier cycles, so that the data update frequency of the high-frequency square wave injection method is increased from the original frequency of the injected high-frequency square wave voltage signal to the N-frequency division of the carrier frequency, that is, no matter how much the period of the injected high-frequency square wave voltage signal is, the angle between the assumed coordinate system and the rotating coordinate system is calculated according to the carrier period / N, which can greatly improve the update speed of the motor estimated speed and angle, thereby improving the response speed of the motor.

[0055] In a specific embodiment, N is a positive integer, k is a positive integer greater than 1, and for example, k is 2 and N is 1. Then, in the assumed coordinate system, r After the high-frequency square wave voltage signal is injected into the axis, the three-phase current signal of the permanent magnet synchronous motor 20 is obtained in each carrier cycle, and in each carrier cycle, the angle between the assumed coordinate system and the rotating coordinate system is determined according to the three-phase current signals corresponding to the current carrier cycle and the previous carrier cycle. In this way, the data update frequency of the high-frequency square wave injection method is increased from the original frequency of the injected high-frequency square wave voltage signal to the same as the carrier frequency, that is, no matter how much the period of the injected high-frequency square wave voltage signal is, the angle between the assumed coordinate system and the rotating coordinate system is calculated according to the carrier cycle, which greatly improves the update speed of the motor estimated speed and angle, thereby improving the response speed of the motor.

[0056] In one embodiment of the present invention, Figure 4 As shown, when determining the angle between the assumed coordinate system and the rotating coordinate system according to the three-phase current signal corresponding to the current carrier cycle and the (k-1)Nth carrier cycle, the controller is configured to: determine the angle q corresponding to the current carrier cycle in the assumed coordinate system according to the three-phase current signal corresponding to the current carrier cycle rThe response current signal of the axis; and, according to the three-phase current signal corresponding to the (k-1)Nth carrier cycle, determine the q corresponding to the (k-1)Nth carrier cycle in the assumed coordinate system. r The response current signal of the axis; according to the q corresponding to the current carrier cycle r The response current signal of the axis and the q corresponding to the (k-1)Nth carrier cycle r The response current signal of the axis determines the angle between the assumed coordinate system and the rotating coordinate system.

[0057] In a specific embodiment, the current carrier cycle is the kNth carrier cycle, such as Figure 3 As shown, the three-phase current i of the permanent magnet synchronous motor is sampled in the current carrier cycle and the (k-1)Nth carrier cycle respectively. u 、i v 、i w After Clark (3s / 2s) transformation and Park (2s / 2r) transformation, we can get the q corresponding to the current carrier period and the (k-1)Nth carrier period in the assumed coordinate system. r The response current signal of the axis is obtained according to the q corresponding to the current carrier cycle. r The response current signal of the axis and the q corresponding to the (k-1)Nth carrier cycle r The response current signal of the axis determines the angle between the assumed coordinate system and the rotating coordinate system.

[0058] In one embodiment of the present invention, the q corresponding to the current carrier cycle is determined in the assumed coordinate system according to the three-phase current signal corresponding to the current carrier cycle. r When the response current signal of the axis is obtained, the controller is configured to: obtain the q corresponding to the current carrier cycle by Clark transformation and Park transformation of the three-phase current signal corresponding to the current carrier cycle r The response current signal of the axis.

[0059] In a specific embodiment, the current carrier cycle is the kNth carrier cycle, such as Figure 3 As shown, in the assumed coordinate system d r After the high-frequency square wave signal is injected into the shaft, the three-phase current i of the permanent magnet synchronous motor is sampled at the kNth carrier cycle. u 、i v 、i w After Clark (3s / 2s) transformation and Park (2s / 2r) transformation, the response current signal i corresponding to the current carrier cycle in the assumed coordinate system can be obtained. q (q r axis response current).

[0060] In one embodiment of the present invention, the q corresponding to the (k-1)Nth carrier cycle is determined in the assumed coordinate system according to the three-phase current signal corresponding to the (k-1)Nth carrier cycle. r When the response current signal of the axis is obtained, the controller is configured to: transform the three-phase current signal corresponding to the (k-1)Nth carrier cycle through Clark transformation and Park transformation to obtain the q corresponding to the (k-1)Nth carrier cycle r The response current signal of the axis.

[0061] In a specific embodiment, as in the previous embodiment, Figure 3 As shown, in the assumed coordinate system d r After the high-frequency square wave signal is injected into the axis, the three-phase current i of the permanent magnet synchronous motor is sampled at the (k-1)Nth carrier cycle. u 、i v 、i w After Clark (3s / 2s) transformation and Park (2s / 2r) transformation, we can get the q corresponding to the (k-1)Nth carrier period in the assumed coordinate system. r The response current signal of the axis.

[0062] In one embodiment of the present invention, according to q corresponding to the current carrier cycle r The response current signal of the axis and the q corresponding to the (k-1)Nth carrier cycle r When the response current signal of the axis determines the angle between the assumed coordinate system and the rotating coordinate system, the controller is configured to perform the following calculation:

[0063]

[0064]

[0065]

[0066] Among them, θ err is the angle between the assumed coordinate system and the rotated coordinate system, I q[kN] is the q corresponding to the current carrier period r The response current of the shaft, I q[(k-1)N] is the q corresponding to the (k-1)Nth carrier period r The response current of the axis, T is the carrier period, u dh is the d of the permanent magnet synchronous motor after injecting high-frequency square wave voltage signal r Shaft voltage, L d , L q are the d-axis inductance and q-axis inductance of the permanent magnet synchronous motor respectively, and N is a positive integer.

[0067] In one embodiment of the present invention, the controller is configured to perform the following calculation:

[0068] When u dh >0,

[0069] When u dh <0,

[0070] In a specific embodiment, the injected high-frequency square wave signal is, for example:

[0071]

[0072] Among them, u dh is d in the assumed coordinate system r The high-frequency square wave signal injected on the axis, U is the amplitude of the high-frequency square wave signal, u qh is q in the assumed coordinate system r The high-frequency square wave signal injected on the axis. Substituting the high-frequency square wave signal into equation (6), we can get:

[0073]

[0074]

[0075]

[0076] in, is the q-axis response current of the permanent magnet synchronous motor after injecting high-frequency square wave signal, θ err is the angle between the assumed coordinate system and the rotated coordinate system, u dh is the d of the permanent magnet synchronous motor after injecting high-frequency square wave signal r Shaft voltage, L d , L q They are the d-axis inductance and q-axis inductance of the permanent magnet synchronous motor respectively.

[0077] According to formula (9), Discretization calculation is performed, the sampling period is N carrier cycles, at 2θ err If the 2θ err Approximately equal to sin 2θ err , after a simple transformation of formula (9), we can get:

[0078] Therefore, we can get:

[0079]

[0080]

[0081]

[0082] Among them, θerr is the angle between the assumed coordinate system and the rotated coordinate system, I q[kN] is the q corresponding to the current carrier period r The response current of the shaft, I q[(k-1)N] is the q corresponding to the (k-1)Nth carrier period r The response current of the axis, T is the carrier period, u dh is the d of the permanent magnet synchronous motor after injecting high-frequency square wave voltage signal r Shaft voltage, L d , L q are the d-axis inductance and q-axis inductance of the permanent magnet synchronous motor respectively, and N is a positive integer.

[0083] In a specific embodiment, Figure 5 As shown, k is 2, N is 1, and the injected high-frequency square wave voltage signal consists of 10 carrier signal cycles, that is, in the assumed coordinate system d r After the high-frequency square wave voltage signal is injected into the shaft, the three-phase current signal of the permanent magnet synchronous motor is obtained in each carrier cycle, and in each carrier cycle, the angle between the assumed coordinate system and the rotating coordinate system is determined according to the three-phase current signals corresponding to the current carrier cycle and the previous carrier cycle. When determining the angle between the assumed coordinate system and the rotating coordinate system according to the three-phase current signals corresponding to the current carrier cycle and the previous carrier cycle, the embodiment of the present invention no longer uses the edge of the injected high-frequency square wave signal as the calculation point, but uses the carrier cycle as the calculation point, that is, the current difference with the previous carrier cycle is calculated in each carrier cycle, that is, I q[2] -I q[1] , I q[3] -I q[2] , I q[4] -I q[3] …and so on.

[0084] It should be noted that the calculation of the high-frequency response current in the embodiment of the present invention no longer uses the edge of the injected high-frequency square wave signal as the calculation point, but uses every N carrier cycles as the calculation point, that is, the high-frequency response current component is obtained by subtracting the current of the kNth carrier cycle from the current of the (k-1)Nth carrier cycle. In order to ensure the consistency of the polarity of the high-frequency response current component, it is necessary to multiply the difference between the current of the kNth carrier cycle and the current of the (k-1)Nth carrier cycle by the polarity of the injected voltage signal: (I q[kN] -I q[(k-1)N] )sign(u dh), in this way, the angle between the assumed coordinate system and the rotating coordinate system is calculated once every N carrier cycles, so that the data update frequency of the high-frequency square wave injection method is increased from the original frequency of the injected high-frequency square wave voltage signal to N divided by the carrier frequency, that is, no matter how much the period of the injected high-frequency square wave voltage signal is, the angle between the assumed coordinate system and the rotating coordinate system is calculated according to the carrier cycle / N, which simplifies the processing flow and, at the same time, can greatly improve the update speed of the motor estimated speed and angle, thereby improving the response speed of the motor.

[0085] Furthermore, by considering the terms other than the current difference in equation (10) as the gain coefficient k1, we can obtain:

[0086]

[0087] Therefore, if Figure 6 As shown in the figure, when the angle between the assumed coordinate system and the rotating coordinate system is adjusted using a phase-locked loop, when the angle θ between the assumed coordinate system and the rotating coordinate system err When the actual rotor position of the permanent magnet synchronous motor is obtained, the gain coefficient is independent of the frequency of the injected high-frequency square wave signal. r When the frequency of the high-frequency square wave voltage signal on the axis is not fixed, the design of the phase-locked loop can be simplified.

[0088] In one embodiment of the present invention, the d-axis direction of the rotating coordinate system is the N-pole direction of the permanent magnet rotor in the permanent magnet synchronous motor, and the q-axis direction of the rotating coordinate system is the direction of rotating the d-axis direction 90° counterclockwise.

[0089] In a specific embodiment, Figure 2 As shown, the rotating coordinate system is a dq coordinate system, wherein the d-axis direction is the N-pole direction of the permanent magnet rotor in the permanent magnet synchronous motor, and the q-axis direction is the direction of rotating the d-axis direction counterclockwise by 90°.

[0090] In one embodiment of the present invention, according to the three-phase current signal corresponding to the current carrier cycle, the q corresponding to the current carrier cycle in the assumed coordinate system is determined. r After the response current signal of the shaft is obtained, the controller is also configured to: extract the current low-frequency component after Clark transformation and Park transformation of the three-phase current signal corresponding to the current carrier cycle to control the normal operation of the permanent magnet synchronous motor.

[0091] In a specific embodiment, Figure 3 As shown, the three-phase current signal i u 、i v 、i wAfter Clark (3s / 2s) transformation and Park (2s / 2r) transformation, the high-frequency response current is removed by the filter to obtain the current low-frequency component i q1 、i d1 , used for the control of permanent magnet synchronous motors, so that the injected high-frequency square wave signal does not affect the operation of the permanent magnet synchronous motors.

[0092] In one embodiment of the present invention, the household appliance includes at least one of an air conditioner, a washing machine, and a refrigerator.

[0093] Specifically, household appliances include: at least one of air conditioners, washing machines, and refrigerators, and any of them contain permanent magnet synchronous motors, and the above control method can be applied. That is, when determining the actual rotor position of the permanent magnet synchronous motor, the angle between the assumed coordinate system and the rotating coordinate system is calculated once every N carrier cycles, so that the data update frequency of the high-frequency square wave injection method is increased from the original frequency of the injected high-frequency square wave voltage signal to N divided by the carrier frequency, that is, no matter how much the period of the injected high-frequency square wave voltage signal is, the angle between the assumed coordinate system and the rotating coordinate system is calculated according to the carrier period / N, which can greatly improve the update speed of the motor estimated speed and angle, thereby improving the response speed of the motor.

[0094] According to an embodiment of the present invention, the household appliance comprises: a housing, a permanent magnet synchronous motor and a controller. The permanent magnet synchronous motor is arranged in the housing and is used to operate according to a DC input voltage; the controller is configured to: r A high-frequency square wave voltage signal is injected into the axis, and the three-phase current signal of the permanent magnet synchronous motor is obtained every N carrier cycles. In the kNth carrier cycle, the angle between the assumed coordinate system and the rotating coordinate system is determined according to the three-phase current signal corresponding to the current carrier cycle and the (k-1)Nth carrier cycle, wherein N is a positive integer and k is a positive integer greater than 1. According to the angle between the assumed coordinate system and the rotating coordinate system, the real rotor position of the permanent magnet synchronous motor is determined, so that the data update frequency of the high-frequency square wave injection method is increased from the original frequency of the injected high-frequency square wave voltage signal to the N-frequency division of the carrier frequency, that is, no matter how much the period of the injected high-frequency square wave voltage signal is, the angle between the assumed coordinate system and the rotating coordinate system is calculated according to the carrier cycle / N, which can greatly improve the update speed of the motor estimated speed and angle, thereby improving the response speed of the motor. Furthermore, when using a phase-locked loop to adjust the angle between the assumed coordinate system and the rotating coordinate system, the gain coefficient is made independent of the frequency of the injected high-frequency square wave signal. When the d r When the frequency of the high-frequency square wave voltage signal on the axis is not fixed, the design of the phase-locked loop can be simplified.

[0095] A further embodiment of the present invention also discloses a method for controlling a household appliance. Figure 7 FIG. 1 is a flow chart of a method for controlling a household appliance according to an embodiment of the present invention. Figure 7 As shown, a method for controlling a household appliance comprises the following steps:

[0096] Step S1: In the assumed coordinate system d r A high-frequency square wave voltage signal is injected into the shaft, and the three-phase current signal of the permanent magnet synchronous motor is obtained every N carrier cycles.

[0097] Step S2: In the kNth carrier cycle, determine the angle between the assumed coordinate system and the rotating coordinate system according to the three-phase current signal corresponding to the current carrier cycle and the (k-1)Nth carrier cycle; wherein N is a positive integer and k is a positive integer greater than 1.

[0098] Step S3: Determine the actual rotor position of the permanent magnet synchronous motor according to the angle between the assumed coordinate system and the rotating coordinate system.

[0099] In one embodiment of the present invention, when determining the angle between the assumed coordinate system and the rotating coordinate system according to the three-phase current signal corresponding to the current carrier cycle and the (k-1)Nth carrier cycle, the controller is configured to: determine the angle q corresponding to the current carrier cycle in the assumed coordinate system according to the three-phase current signal corresponding to the current carrier cycle r The response current signal of the axis; and, according to the three-phase current signal corresponding to the (k-1)Nth carrier cycle, determine the q corresponding to the (k-1)Nth carrier cycle in the assumed coordinate system. r The response current signal of the axis; according to the q corresponding to the current carrier cycle r The response current signal of the axis and the q corresponding to the (k-1)Nth carrier cycle r The response current signal of the axis determines the angle between the assumed coordinate system and the rotating coordinate system.

[0100] In one embodiment of the present invention, the q corresponding to the current carrier cycle is determined in the assumed coordinate system according to the three-phase current signal corresponding to the current carrier cycle. r When the response current signal of the axis is obtained, the controller is configured to: obtain the q corresponding to the current carrier cycle by Clark transformation and Park transformation of the three-phase current signal corresponding to the current carrier cycle r The response current signal of the axis.

[0101] In one embodiment of the present invention, the q corresponding to the (k-1)Nth carrier cycle is determined in the assumed coordinate system according to the three-phase current signal corresponding to the (k-1)Nth carrier cycle. rWhen the response current signal of the axis is obtained, the controller is configured to: transform the three-phase current signal corresponding to the (k-1)Nth carrier cycle through Clark transformation and Park transformation to obtain the q corresponding to the (k-1)Nth carrier cycle r The response current signal of the axis.

[0102] In one embodiment of the present invention, according to q corresponding to the current carrier cycle r The response current signal of the axis and the q corresponding to the (k-1)Nth carrier cycle r When the response current signal of the axis determines the angle between the assumed coordinate system and the rotating coordinate system, the controller is configured to perform the following calculation:

[0103]

[0104]

[0105]

[0106] Among them, θ err is the angle between the assumed coordinate system and the rotated coordinate system, I q[kN] is the q corresponding to the current carrier period r The response current of the shaft, I q[(k-1)N] is the q corresponding to the (k-1)Nth carrier period r The response current of the axis, T is the carrier period, u dh is the d of the permanent magnet synchronous motor after injecting high-frequency square wave voltage signal r Shaft voltage, L d , L q are the d-axis inductance and q-axis inductance of the permanent magnet synchronous motor respectively, and N is a positive integer.

[0107] In one embodiment of the present invention, the controller is configured to perform the following calculation:

[0108] When u dh >0,

[0109] When u dh <0,

[0110] In one embodiment of the present invention, when determining the true rotor position of a permanent magnet synchronous motor based on the angle between the assumed coordinate system and the rotating coordinate system, the controller is configured to: use a phase-locked loop to adjust the angle between the assumed coordinate system and the rotating coordinate system; when the angle between the assumed coordinate system and the rotating coordinate system is zero, the true rotor position of the permanent magnet synchronous motor is obtained.

[0111] In one embodiment of the present invention, the d-axis direction of the rotating coordinate system is the N-pole direction of the permanent magnet rotor in the permanent magnet synchronous motor, and the q-axis direction of the rotating coordinate system is the direction of rotating the d-axis direction 90° counterclockwise.

[0112] In one embodiment of the present invention, according to the three-phase current signal corresponding to the current carrier cycle, the q corresponding to the current carrier cycle in the assumed coordinate system is determined. r After the response current signal of the shaft is obtained, the controller is also configured to: extract the current low-frequency component after Clark transformation and Park transformation of the three-phase current signal corresponding to the current carrier cycle to control the normal operation of the permanent magnet synchronous motor.

[0113] It should be noted that when the control method of the household appliance in the embodiment of the present invention controls the household appliance, its specific implementation method is similar to the specific implementation method of the household appliance in the embodiment of the present invention. Please refer to the description of the household appliance part for details. In order to reduce redundancy, it will not be repeated here.

[0114] According to the control method of the household appliance of the embodiment of the present invention, by assuming the coordinate system d r A high-frequency square wave voltage signal is injected into the axis, and the three-phase current signal of the permanent magnet synchronous motor is obtained every N carrier cycles. In the kNth carrier cycle, the angle between the assumed coordinate system and the rotating coordinate system is determined according to the three-phase current signal corresponding to the current carrier cycle and the (k-1)Nth carrier cycle, wherein N is a positive integer and k is a positive integer greater than 1; according to the angle between the assumed coordinate system and the rotating coordinate system, the real rotor position of the permanent magnet synchronous motor is determined, so that the data update frequency of the high-frequency square wave injection method is increased from the original frequency of the injected high-frequency square wave voltage signal to the N-frequency division of the carrier frequency, that is, no matter how much the period of the injected high-frequency square wave voltage signal is, the angle between the assumed coordinate system and the rotating coordinate system is calculated according to the carrier cycle / N, which can greatly improve the update speed of the motor estimated speed and angle, thereby improving the response speed of the motor. Furthermore, when using a phase-locked loop to adjust the angle between the assumed coordinate system and the rotating coordinate system, the gain coefficient is made independent of the frequency of the injected high-frequency square wave signal, and when the d injected into the assumed coordinate system is r When the frequency of the high-frequency square wave voltage signal on the axis is not fixed, the design of the phase-locked loop can be simplified.

[0115] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example.

[0116] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A household appliance, characterized in that: include: case; a permanent magnet synchronous motor, disposed in the housing and configured to operate according to a DC input voltage; The controller is configured as follows: r A high-frequency square wave voltage signal is injected into the shaft, and the three-phase current signal of the permanent magnet synchronous motor is obtained every N carrier cycles; In the kNth carrier cycle, the angle between the assumed coordinate system and the rotating coordinate system is determined according to the three-phase current signal corresponding to the current carrier cycle and the (k-1)Nth carrier cycle; wherein N is a positive integer and k is a positive integer greater than 1; The actual rotor position of the permanent magnet synchronous motor is determined according to the angle between the assumed coordinate system and the rotating coordinate system.

2. The household appliance according to claim 1, characterized in that: When determining the angle between the assumed coordinate system and the rotating coordinate system according to the three-phase current signal corresponding to the current carrier cycle and the (k-1)Nth carrier cycle, the controller is configured as follows: According to the three-phase current signal corresponding to the current carrier cycle, the q corresponding to the current carrier cycle in the assumed coordinate system is determined. r The response current signal of the axis; And, according to the three-phase current signal corresponding to the (k-1)Nth carrier cycle, determine the q corresponding to the (k-1)Nth carrier cycle in the assumed coordinate system. r The response current signal of the axis; According to the q corresponding to the current carrier cycle r The response current signal of the axis and the q corresponding to the (k-1)Nth carrier cycle r The response current signal of the shaft determines the angle between the assumed coordinate system and the rotating coordinate system.

3. The household appliance according to claim 2, characterized in that: According to the three-phase current signal corresponding to the current carrier cycle, the q corresponding to the current carrier cycle in the assumed coordinate system is determined. r The controller is configured to: The three-phase current signal corresponding to the current carrier cycle is transformed by Clark transformation and Park transformation to obtain the q corresponding to the current carrier cycle. r The response current signal of the axis.

4. The household appliance according to claim 2, characterized in that: According to the three-phase current signal corresponding to the (k-1)Nth carrier cycle, the q corresponding to the (k-1)Nth carrier cycle in the assumed coordinate system is determined. r The controller is configured to: The three-phase current signal corresponding to the (k-1)Nth carrier cycle is transformed by Clark transformation and Park transformation to obtain the q corresponding to the (k-1)Nth carrier cycle. r The response current signal of the axis.

5. The household appliance according to claim 2, characterized in that: According to the q corresponding to the current carrier cycle r The response current signal of the axis and the q corresponding to the (k-1)Nth carrier cycle r When the angle between the assumed coordinate system and the rotating coordinate system is determined based on the response current signal of the axis, the controller is configured to perform the following calculation: Among them, θ err is the angle between the assumed coordinate system and the rotated coordinate system, I q[kN] is the q corresponding to the current carrier period r The response current of the shaft, I q[()] is the q corresponding to the (k-1)Nth carrier period r The response current of the axis, T is the carrier period, u dh is the d of the permanent magnet synchronous motor after the high frequency square wave voltage signal is injected r Shaft voltage, L d , L q are the d-axis inductance and q-axis inductance of the permanent magnet synchronous motor respectively, and N is a positive integer.

6. The household appliance according to claim 5, characterized in that: The controller is configured to perform the following calculation: When u dh >0, When u dh <0, 7. The household appliance according to claim 1, characterized in that: When determining the true rotor position of the permanent magnet synchronous motor according to the angle between the assumed coordinate system and the rotating coordinate system, the controller is configured as follows: Using a phase-locked loop to adjust the angle between the assumed coordinate system and the rotating coordinate system; When the angle between the assumed coordinate system and the rotating coordinate system is zero, the true rotor position of the permanent magnet synchronous motor is obtained.

8. The household appliance according to claim 1, characterized in that: The d-axis direction of the rotating coordinate system is the N-pole direction of the permanent magnet rotor in the permanent magnet synchronous motor, and the q-axis direction of the rotating coordinate system is the direction of rotating the d-axis direction by 90° counterclockwise.

9. The household appliance according to claim 3, characterized in that: According to the three-phase current signal corresponding to the current carrier cycle, the q corresponding to the current carrier cycle in the assumed coordinate system is determined. r After the response current signal of the shaft, the controller is also configured to: After the three-phase current signal corresponding to the current carrier cycle is subjected to the Clark transformation and the Park transformation, the current low-frequency component is extracted to control the normal operation of the permanent magnet synchronous motor.

10. A method for controlling a household appliance, characterized in that: include: In the assumed coordinate system d r A high-frequency square wave voltage signal is injected into the shaft, and the three-phase current signal of the permanent magnet synchronous motor is obtained every N carrier cycles; In the kNth carrier cycle, the angle between the assumed coordinate system and the rotating coordinate system is determined according to the three-phase current signal corresponding to the current carrier cycle and the (k-1)Nth carrier cycle; wherein N is a positive integer and k is a positive integer greater than 1; The actual rotor position of the permanent magnet synchronous motor is determined according to the angle between the assumed coordinate system and the rotating coordinate system.

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