Temperature monitoring method, temperature monitoring device and monitoring system

Abstract

The present disclosure relates to a temperature monitoring method, a temperature monitoring device and a monitoring system. A temperature monitoring method is disclosed for monitoring the temperature of a permanent magnet of a permanent magnet synchronous motor, comprising: obtaining the flux temperature coefficient of the permanent magnet in advance, the flux temperature coefficient being a proportional factor of the flux of the permanent magnet changing in proportion to the temperature; obtaining the reference temperature and reference flux of the permanent magnet in advance; keeping the motor running at a reference speed for a short period of time in advance so that the temperature of the permanent magnet is the reference temperature and the flux is the reference flux, changing the stator current in this state, and obtaining a set of reference stator voltages corresponding to different stator currents; obtaining the real-time stator current, the real-time stator voltage and the real-time speed of the rotor in real time when the motor is running; calculating the temperature of the permanent magnet using the real-time stator current, the real-time stator voltage and the real-time speed as well as the flux temperature coefficient, the reference temperature, the reference flux, the reference speed and the reference stator voltage corresponding to the real-time stator current.

Description

Technical Field

[0001] The present disclosure relates to monitoring of a permanent magnet synchronous motor, and in particular, to a temperature monitoring method and a temperature monitoring device for measuring the temperature of a permanent magnet of a permanent magnet synchronous motor, and a permanent magnet synchronous motor monitoring system including the temperature monitoring device. Background Art

[0002] Permanent magnets are arranged on the rotor of a permanent magnet synchronous motor to generate the magnetic field required for the motor to operate. However, permanent magnet materials are temperature-dependent, and as the temperature of the permanent magnet increases, the magnetic flux of the permanent magnet decreases. Therefore, as the temperature of the permanent magnet increases, the torque density of the permanent magnet synchronous motor decreases. Moreover, when the temperature of the permanent magnet exceeds the maximum operating temperature, the permanent magnet may be permanently demagnetized, causing serious damage to both the permanent magnet and the motor. Acquiring the temperature of the permanent magnet in real time while the motor is running helps to more effectively control the motor in response to the influence of temperature, and can monitor the state of the permanent magnet to avoid irreversible permanent demagnetization, thereby better monitoring and controlling the operating state of the permanent magnet synchronous motor.

[0003] Therefore, it is very important to obtain the temperature of the permanent magnet in real time when the permanent magnet synchronous motor is running.

[0004] However, when the permanent magnet synchronous motor is running, the rotor is in a rotating state, so it is difficult to directly measure the permanent magnet temperature through a temperature sensor. Existing methods for estimating the permanent magnet temperature mainly include the following categories: methods based on thermal networks, methods based on motor models, and methods based on sensors. However, these methods all have certain disadvantages.

[0005] The thermal network-based method estimates the temperature of the permanent magnet by building a thermal network model of the motor. This method requires geometric information of the motor, which is not always available in practical applications. In addition, the thermal network-based method requires accurate ambient temperature. In practical applications, especially in electric vehicles, motors are often installed in compact and harsh spaces. Therefore, the ambient temperature is affected by many factors and cannot be accurately obtained.

[0006] Motor model-based methods can be further divided into non-invasive methods and invasive methods.

[0007] In the non-invasive method, the temperature of the permanent magnet is estimated by the temperature-dependent permanent magnet flux linkage. The flux linkage of the permanent magnet is estimated based on the electrical model of the motor using known nominal motor parameters (such as winding resistance and inductance) and real-time measured motor operation data (such as stator current). The advantage of this method is its non-invasiveness, as it does not interfere with the drive of the motor. However, this method estimates the flux linkage of the permanent magnet by treating the nominal parameters of the motor, such as winding resistance and inductance, as constant values, but when the motor is running, the winding resistance and inductance will deviate from their nominal values ​​due to the increase in winding temperature and magnetic saturation. Therefore, the accuracy of the flux linkage and temperature of the permanent magnet estimated by this method will also be affected by the increase in winding temperature and the magnetic saturation of the motor accordingly.

[0008] In the intrusive method, a high-frequency signal is injected into the motor to estimate the high-frequency impedance. Since the high-frequency impedance is related to the temperature, the temperature of the permanent magnet can be estimated based on the high-frequency impedance. However, the injection of the high-frequency signal affects the drive of the motor, which has an adverse effect. Therefore, this method is somewhat intrusive and will cause additional losses and torque pulsations in the motor, which is usually not allowed in industrial drives.

[0009] Sensor-based methods use sensors to measure certain parameters of the motor to estimate the flux of the permanent magnet and, in turn, the temperature of the permanent magnet. In a typical approach, Hall sensors can be appropriately installed in the motor to measure the magnetic field voltage generated by the rotation of the rotor, which is proportional to the flux of the permanent magnet. Thus, the permanent magnet temperature is estimated by the voltage measurement results of the Hall sensor. However, in practical applications, the installation of sensors in the motor will bring certain challenges.

[0010] Therefore, there is a need for an improved temperature monitoring method for measuring the temperature of the permanent magnets of a permanent magnet synchronous motor. Summary of the invention

[0011] One of the objectives of the present disclosure is to provide an improved temperature monitoring method for measuring the temperature of a permanent magnet of a permanent magnet synchronous motor.

[0012] According to one aspect of the present disclosure, a temperature monitoring method is provided for monitoring the temperature T(t) of a permanent magnet of a permanent magnet synchronous motor, the method comprising: obtaining in advance a flux temperature coefficient β of the permanent magnet, the flux temperature coefficient β being a proportional factor by which the flux of the permanent magnet changes in proportion to the temperature; obtaining in advance a reference temperature T0 and a reference flux φ0 of the permanent magnet; preliminarily maintaining the motor at a reference speed ω0 for a short period of time so that the temperature of the permanent magnet is the reference temperature T0 and the flux is the reference flux φ0, and in this state, changing the stator current of the motor to obtain a set of reference stator voltages u corresponding to different stator currents d0 ,uq0 When the motor is running, the real-time stator current i of the motor is obtained in real time d (t),i q (t), real-time stator voltage u d (t),u q (t) and the real-time speed of the rotor ω(t); using the real-time stator current i d (t),i q (t), real-time stator voltage u d (t),u q (t) and real-time speed ω(t), as well as the pre-acquired flux temperature coefficient β, reference temperature T0, reference flux φ0, reference speed ω0 and the set of reference stator voltages u d0 ,u q0 The real-time stator current i d (t),i q (t) Corresponding reference stator voltage u d0 ,u q0 , calculate the temperature T(t) of the permanent magnet.

[0013] According to another aspect of the present disclosure, a temperature monitoring device is provided for monitoring the temperature of a permanent magnet of a permanent magnet synchronous motor, wherein the temperature monitoring device is configured to execute the aforementioned temperature monitoring method.

[0014] According to another aspect of the present disclosure, a monitoring system is provided for monitoring the operation of a permanent magnet synchronous motor, wherein the monitoring system includes the aforementioned temperature monitoring device.

[0015] Other features and advantages of the present disclosure will become more apparent from the following detailed description of exemplary embodiments of the present disclosure with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings, which constitute a part of the specification, illustrate embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0017] The present disclosure may be more clearly understood from the following detailed description with reference to the accompanying drawings, in which:

[0018] Figure 1 A flow chart of a temperature monitoring method for measuring the temperature of a permanent magnet of a permanent magnet synchronous motor according to an exemplary embodiment of the present disclosure is shown.

[0019] Figure 2 A schematic block diagram of a monitoring system for monitoring the operation of a permanent magnet synchronous motor according to an exemplary embodiment of the present disclosure is shown.

[0020] Note that in the embodiments described below, sometimes the same reference numerals are used in common between different drawings to represent the same parts or parts with the same functions, and their repeated descriptions are omitted. In some cases, similar numbers and letters are used to represent similar items, so once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0021] For ease of understanding, the position, size, range, etc. of each structure shown in the drawings and the like may not represent the actual position, size, range, etc. Therefore, the present disclosure is not limited to the position, size, range, etc. disclosed in the drawings and the like. DETAILED DESCRIPTION

[0022] Various exemplary embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. It should be noted that unless otherwise specifically stated, the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present disclosure.

[0023] The following description of at least one exemplary embodiment is in fact merely illustrative and is in no way intended to limit the present disclosure and its application or use. That is, the structures and methods herein are shown in an exemplary manner to illustrate different embodiments of the structures and methods in the present disclosure. However, those skilled in the art will appreciate that they merely illustrate exemplary ways of the present disclosure that can be implemented, rather than exhaustive ways. In addition, the drawings need not be drawn to scale, and some features may be enlarged to illustrate the details of specific components.

[0024] Technologies, methods, and apparatus known to ordinary technicians in the relevant field may not be discussed in detail, but where appropriate, such technologies, methods, and apparatus should be considered part of the authorization specification.

[0025] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0026] The present disclosure proposes a method for estimating the temperature of a permanent magnet based on a steady-state model of a motor. The permanent magnet temperature can be estimated based on real-time measurement data of the motor without using motor parameters such as winding resistance and inductance that may change during motor operation due to factors such as increased winding temperature and magnetic saturation. Therefore, the method proposed in the present disclosure will not be affected by these changing and inaccurate parameters, thereby showing a higher accuracy.

[0027] The following is based on the steady-state model of the motor to derive the relationship between the permanent magnet temperature and the real-time electrical state of the motor.

[0028] At any time t, the steady-state model of the permanent magnet synchronous motor can be expressed as:

[0029]

[0030] Among them, u d (t),u q (t) is the dq axis stator voltage at time t, i d (t),i q (t) is the dq-axis stator current at time t, ω(t) is the rotor speed (electrical angular velocity) at time t, φ(t) is the permanent magnet flux at time t, L d (t), L q (t) is the time between time t and i d (t),i q (t) is the corresponding dq-axis stator inductance, and R is the winding resistance.

[0031] When the motor is running, the winding resistance R and the permanent magnet flux φ(t) depend on the winding temperature and the permanent magnet temperature respectively. Therefore, based on equation (1), the dq-axis stator voltage u d (t),u q (t) also depends on the winding temperature and the permanent magnet temperature. The present disclosure aims to use the stator voltage u based on equation (1) d (t),u q (t), stator current i d (t),i q The permanent magnet temperature at time t is estimated by measuring the rotational speed ω(t) and the rotor speed ω(t).

[0032] Multiply the first equation in equation (1) by i q (t), multiply the second formula by i d (t), we can get:

[0033]

[0034] Subtract the first equation from the second equation in equation (2), and we get:

[0035]

[0036] That is, at any time t, the stator voltage u d (t),u q (t), stator current i d (t),i q (t), rotor speed ω(t), permanent magnet flux φ(t) and stator inductance L d (t), L q (t) satisfies formula (3).

[0037] On the other hand, when the motor is running, the increase in permanent magnet temperature will lead to a decrease in permanent magnet flux. A linear model can be used to describe the relationship between the change in permanent magnet flux and permanent magnet temperature, as shown below:

[0038] φ(t)=φ0(1+β(T(t)-T0)) (4)

[0039] Wherein, T(t) represents the permanent magnet temperature at any time t, φ(t) represents the permanent magnet flux linkage when the permanent magnet temperature is T(t) at time t; T0 represents the reference temperature of the permanent magnet (for example, the initial temperature when the permanent magnet temperature has not yet increased), φ0 represents the reference flux linkage of the permanent magnet when the permanent magnet temperature is T0; β is the flux linkage temperature coefficient.

[0040] The motor is made to run at a low speed of reference speed ω0 for a short period of time, so that the permanent magnet temperature is the reference temperature T0 and the permanent magnet flux is the reference flux φ0. At this time, the motor is in the reference state. In the reference state, the temperature of the permanent magnet has not increased significantly, and the various parameters of the motor are not affected by factors such as temperature. Therefore, the reference temperature T0 and the reference flux φ0 can be simply obtained by measurement or calculation.

[0041] In the reference state, the rotor speed of the motor is kept at the reference speed ω0, and the dq axis stator current i is changed. d0 ,i q0 , measured with different dq axis stator current i d0 ,i q0 The corresponding set of dq axis stator voltage u d0 ,u q0 For the sake of clarity, the stator current and the corresponding stator voltage obtained in the reference state may be referred to as the reference stator current i and i respectively. d0 ,i q0 and the reference stator voltage u d0 ,u q0 .

[0042] Note that the electrical state of the motor should also satisfy equation (3). In this way, in the reference state, for any reference stator current i d0 ,i q0 And the corresponding reference stator voltage u d0 ,u q0 , from formula (3):

[0043]

[0044] Among them, L d0 , L q0 is the reference stator current i d0 ,i q0 The dq-axis stator inductance.

[0045] Note that for any reference stator current i under the reference state (i.e., the motor runs at a low speed of reference speed ω0 for a short period of time, so that the permanent magnet temperature is the reference temperature T0 and the permanent magnet flux is the reference flux φ0), equation (5) is d0 ,i q0 And the corresponding reference stator voltage u d0 ,u q0 All are established.

[0046] Therefore, in equation (5), the reference stator current i d0 ,i q0 The stator current i at time t is d (t),i q (t). Therefore, the reference stator voltage u d0 ,u q0 The value is the stator current i at time t d (t),i q (t) Corresponding reference stator voltage u d0 ,u q0 In addition, since the reference stator current i d0 ,i q0 The stator current i at time t is d (t),i q (t), the corresponding stator inductance L in formula (5) d0 , L q0 Correspondingly, the stator inductance L at time t d (t), L q (t) are equal.

[0047] Therefore, in the reference state, when the reference stator current i in equation (5) d0 ,i q0 The stator current i at time t is d (t),i q (t), we get:

[0048]

[0049] Subtracting equation (6) from equation (3) yields:

[0050]

[0051] Substituting formula (4) into formula (7), we can get:

[0052]

[0053] Right now

[0054]

[0055] Thus, for any time t, the real-time stator current i can be calculated based on equation (9): d (t),i q (t), real-time stator voltage u d (t),u q (t) and the real-time rotation speed ω(t) of the rotor to calculate the permanent magnet temperature T(t).

[0056] Based on the above derivation, Figure 1 A flow chart of a temperature monitoring method 100 according to an exemplary embodiment of the present disclosure is shown.

[0057] The method 100 starts at block 101 for measuring the temperature of permanent magnets of a permanent magnet synchronous motor.

[0058] At block 102, the flux temperature coefficient β of the permanent magnet is obtained in advance. The flux temperature coefficient β is a proportional factor that changes the flux φ(t) of the permanent magnet in proportion to the change of the permanent magnet temperature T(t). The relationship between the flux φ(t) of the permanent magnet and the permanent magnet temperature T(t) satisfies equation (4).

[0059] The flux temperature coefficient β is related to the material of the permanent magnet and can be simply obtained by measurement. For example, for a permanent magnet made of NdFeB material, the flux temperature coefficient β is about -0.12% / °C. In a preferred embodiment, the flux temperature coefficient β can be pre-stored in a storage device.

[0060] At block 104, a reference temperature T0 and a reference flux φ0 of the permanent magnet are obtained in advance. The reference temperature T0 and the reference flux φ0 of the permanent magnet are the temperature and flux of the permanent magnet when the motor temperature has not increased significantly and the flux and other parameters of the motor are not affected by factors such as temperature.

[0061] The reference temperature T0 and the reference flux φ0 of the permanent magnet may be measured and / or calculated in an appropriate manner as required. In a preferred embodiment, the ambient temperature of the motor may be measured as the reference temperature T0. In a preferred embodiment, the reference temperature T0 and the reference flux φ0 of the permanent magnet may be stored in advance in a storage device.

[0062] At block 106, the motor is kept running at a reference speed ω0 for a short period of time so that the temperature of the permanent magnet is the reference temperature T0 and the flux is the reference flux φ0, that is, the motor is kept in a reference state. In the reference state of the motor, the rotor speed is kept at the reference speed ω0, and the stator current of the motor is changed (that is, the reference stator current is changed) i d0 ,i q0 , get the stator current i with different d0 ,i q0 The corresponding set of reference stator voltages u d0,u q0 .

[0063] In a preferred embodiment, the reference speed ω0 is selected as a relatively low speed to ensure that the temperature of the permanent magnet is maintained at the reference temperature T0 and the flux is maintained at the reference flux φ0 during the short period. For example, the reference speed ω0 can be selected as about 100 r / min.

[0064] In a preferred embodiment, the above-mentioned reference stator current i d0 ,i q0 The corresponding set of reference stator voltages u d0 ,u q0 In a further preferred embodiment, the above-mentioned reference stator current i d0 ,i q0 The corresponding set of reference stator voltages u d0 ,u q0 Stored in the storage device in the form of a lookup table.

[0065] At box 108 , the motor begins running.

[0066] At block 110 , when the motor is running, the real-time stator current i of the motor is obtained in real time. d (t),i q (t), real-time stator voltage u d (t),u q (t) and the real-time speed of the rotor ω(t).

[0067] The real-time stator current i of the motor can be measured and / or calculated in an appropriate manner as required. d (t),i q (t), real-time stator voltage u d (t),u q (t) and the real-time speed of the rotor ω(t). In a preferred embodiment, the average value I of the stator current and the stator voltage in one or more electrical cycles can be obtained. d (t), I q (t), U d (t), U q (t), and the average value is used to calculate the temperature T(t) of the permanent magnet.

[0068] At block 112, the real-time stator current i d (t),i q (t), real-time stator voltage u d (t),u q(t) and real-time speed ω(t), as well as the pre-acquired flux temperature coefficient β, reference temperature T0, reference flux φ0, reference speed ω0 and the above-mentioned set of reference stator voltages u d0 ,u q0 The real-time stator current i d (t),i q (t) Corresponding reference stator voltage u d0 ,u q0 , the temperature T(t) of the permanent magnet is calculated based on equation (9).

[0069] In a preferred embodiment, when the motor is running, the pre-stored flux temperature coefficient β, reference temperature T0, reference flux φ0, reference speed ω0 and the above-mentioned set of reference stator voltage u can be obtained from the storage device. d0 ,u q0 The real-time stator current i d (t),i q (t) Corresponding reference stator voltage u d0 ,u q0 at least one of .

[0070] In a preferred embodiment, a linear Gaussian system can be used to perform state estimation based on equation (9) to calculate the temperature T(t) of the permanent magnet, thereby reducing the influence of errors and further improving the accuracy of the calculated permanent magnet temperature T(t).

[0071] Since the temperature of the permanent magnet changes slowly, it can be considered to change linearly with time in a short period of time. That is, the temperature change T(t)-T(t-1) of the permanent magnet can be linearized with respect to time:

[0072] T(t)-T(t-1)=k M (t)Δt (10)

[0073] To further simplify the model, we can assume that k M (t) = k M (t-1).

[0074] Therefore, the difference between the temperature T(t) of the permanent magnet and the reference temperature T0 can be regarded as a state, and the slope k of the temperature change T(t)-T(t-1) of the permanent magnet relative to time can be regarded as M (t) As another state, the following linear Gaussian system is used for state estimation:

[0075] The state of this linear Gaussian system is

[0076]

[0077] The measurement quantity is

[0078]

[0079] Its satisfaction

[0080]

[0081] in

[0082]

[0083] Among them, A is the state transfer matrix, B is the measurement matrix, g t and e t represent random vectors and measurement noise respectively. g can be appropriately determined as needed t and e t to improve the accuracy of state estimation.

[0084] In a preferred embodiment, Kalman filtering can be used for state estimation. In other embodiments, other methods can be used to appropriately estimate the state of the linear Gaussian system to calculate the temperature T(t) of the permanent magnet.

[0085] At box 114, the calculated temperature T(t) of the permanent magnet is stored in a storage device and / or transmitted to a remote end via a wired or wireless link. In a preferred embodiment, the calculated temperature T(t) of the permanent magnet is transmitted to a remote monitoring system to be displayed to a user and further processed and analyzed.

[0086] At box 116, it is determined whether it is still necessary to continue monitoring the temperature of the permanent magnet. If yes, the method 100 returns to box 110 to continue acquiring the real-time stator current i of the motor. d (t),i q (t), real-time stator voltage u d (t),u q (t) and the real-time rotation speed ω(t) of the rotor. If not, the method 100 ends at block 118. In a preferred embodiment, the temperature of the permanent magnet may be monitored at certain time intervals (eg, several seconds).

[0087] Figure 2 A schematic block diagram of a monitoring system 200 according to an exemplary embodiment of the present disclosure is shown.

[0088] The monitoring system 200 is used to monitor the operation of the motor 201, and may include a temperature monitoring device 210, a rotation speed measuring device 220, and a motor control device 230. The motor 201 is a permanent magnet synchronous motor.

[0089] The temperature monitoring device 210 may perform Figure 1The temperature monitoring method 100 shown is used to monitor the temperature of the permanent magnet of the motor 201 when the motor 201 is running. In a preferred embodiment, the temperature monitoring device 210 may include a storage device (not shown) for storing the flux temperature coefficient β, the reference temperature T0, the reference flux φ0, the reference speed ω0 of the motor 201, and a set of reference stator voltages u corresponding to different reference stator currents. d0 ,u q0 at least one of .

[0090] The rotation speed measuring device 220 is communicatively coupled to the temperature monitoring device 210, and is used to measure the rotor rotation speed of the motor 201, and input the measured rotor rotation speed to the temperature monitoring device 220. The rotation speed measuring device 220 can be appropriately implemented by techniques known in the art.

[0091] The motor control device 230 is communicatively coupled to the temperature monitoring device 210, receives the temperature of the permanent magnet from the temperature monitoring device 210, and controls the operation of the motor 201 at least partially based on the received temperature of the permanent magnet. In a preferred embodiment, the motor control device 230 can adjust the control parameters based on the received temperature of the permanent magnet to compensate for the effect of the increase in the permanent magnet temperature on the flux linkage. In a preferred embodiment, the motor control device 230 can be a speed / torque control device for controlling the motor 201 to operate at a constant stator current.

[0092] The temperature monitoring device 210 , the rotation speed measuring device 220 and the motor control device 230 may be implemented in various appropriate ways such as software, hardware, or a combination of software and hardware.

[0093] The words "front", "rear", "top", "bottom", "over", "under", etc., if any, in the specification and claims are used for descriptive purposes and are not necessarily used to describe invariant relative positions. It is understood that the words so used are interchangeable under appropriate circumstances such that the embodiments of the disclosure described herein, for example, are capable of operation in other orientations than those illustrated or otherwise described herein.

[0094] As used herein, the word "exemplary" means "serving as an example, instance, or illustration," rather than as a "model" to be exactly copied. Any implementation described as an example herein is not necessarily to be construed as preferred or advantageous over other implementations. Furthermore, the present disclosure is not limited by any expressed or implied theory given in the above technical field, background technology, summary of the invention, or detailed description.

[0095] As used herein, the term "substantially" is meant to include any minor variations due to design or manufacturing imperfections, device or component tolerances, environmental influences, and / or other factors. The term "substantially" also allows for deviations from a perfect or ideal condition due to parasitic effects, noise, and other practical considerations that may be present in actual implementations.

[0096] Additionally, the foregoing description may have referred to elements or nodes or features being "connected" or "coupled" together. As used herein, unless expressly stated otherwise, "connected" means that one element / node / feature is directly connected (or directly communicates) with another element / node / feature, electrically, mechanically, logically, or otherwise. Similarly, unless expressly stated otherwise, "coupled" means that one element / node / feature can be mechanically, electrically, logically, or otherwise connected to another element / node / feature in a direct or indirect manner to allow interaction, even though the two features may not be directly connected. That is, "coupled" is intended to encompass both direct and indirect connections of elements or other features, including connections utilizing one or more intermediate elements.

[0097] In addition, the terms "first", "second", and the like may also be used herein for reference purposes only, and thus are not intended to be limiting. For example, the terms "first", "second", and other such numerical terms referring to structures or elements do not imply a sequence or order unless the context clearly indicates otherwise.

[0098] It should also be understood that when the term “include / comprises” is used in this document, it indicates the presence of the specified features, integers, steps, operations, units and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, units and / or components and / or their combinations.

[0099] In this disclosure, the term "provide" is used in a broad sense to cover all ways of obtaining an object, and thus "providing an object" includes but is not limited to "purchasing", "preparing / manufacturing", "arranging / setting up", "installing / assembling", and / or "ordering" an object, etc.

[0100] Those skilled in the art will appreciate that the boundaries between the above operations are merely illustrative. Multiple operations can be combined into a single operation, a single operation can be distributed in additional operations, and operations can be performed at least partially overlapping in time. Moreover, alternative embodiments may include multiple instances of specific operations, and the order of operations may be changed in other various embodiments. However, other modifications, variations, and replacements are equally possible. Therefore, this specification and accompanying drawings should be considered illustrative, not restrictive.

[0101] Although some specific embodiments of the present disclosure have been described in detail by way of example, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present disclosure. The various embodiments disclosed herein may be combined in any manner without departing from the spirit and scope of the present disclosure. It should also be understood by those skilled in the art that various modifications may be made to the embodiments without departing from the scope and spirit of the present disclosure. The scope of the present disclosure is defined by the appended claims.

Claims

1. A temperature monitoring method for monitoring the temperature T(t) of a permanent magnet of a permanent magnet synchronous motor, characterized in that: The method comprises: Pre-acquire a flux temperature coefficient β of the permanent magnet, wherein the flux temperature coefficient β is a proportional factor of the flux of the permanent magnet that changes in proportion to temperature; Pre-acquire a reference temperature T0 and a reference flux φ0 of the permanent magnet; The motor is kept running at a reference speed ω0 for a short period of time in advance so that the temperature of the permanent magnet is the reference temperature T0 and the flux is the reference flux φ0. In this state, the stator current of the motor is changed to obtain a set of reference stator voltages u corresponding to different stator currents. d0 and u q0 ; When the motor is running, the real-time stator current i of the motor is obtained in real time. d (t) and i q (t), real-time stator voltage u d (t) and u q (t), and the real-time speed of the rotor ω(t); Using the real-time stator current i d (t) and i q (t), real-time stator voltage u d (t) and u q (t), real-time speed ω(t), pre-acquired flux temperature coefficient β, reference temperature T0, reference flux φ0, reference speed ω0, the set of reference stator voltages u d0 and u q0 The real-time stator current i d (t) and i q (t) Corresponding reference stator voltage u d0 and u q0 , calculate the temperature T(t) of the permanent magnet, The temperature of the permanent magnet is calculated based on the following formula: Among them, u d (t) and u q (t) is the dq axis stator voltage at time t, i d (t) and i q (t) is the dq-axis stator current at time t.

2. The temperature monitoring method according to claim 1, characterized in that: A linear Gaussian system is used to perform state estimation to calculate the temperature T(t) of the permanent magnet, wherein the difference between the temperature T(t) of the permanent magnet and a reference temperature T0 is used as a state of the linear Gaussian system.

3. The temperature monitoring method according to claim 2, characterized in that: The temperature change T(t)-T(t-1) of the permanent magnet is linearized with respect to time, and the slope k of the temperature change T(t)-T(t-1) of the permanent magnet with respect to time is M (t) is another state of the linear Gaussian system.

4. The temperature monitoring method according to claim 2 or 3, characterized in that: Kalman filtering is used for state estimation.

5. The temperature monitoring method according to any one of claims 1 to 3, characterized in that: Obtain the real-time stator current i of the motor in real time d (t) and i q (t), real-time stator voltage u d (t) and u q (t) include: Get the average value of stator current and stator voltage in one or more electrical cycles I d (t) and I q (t), U d (t) and U q (t), and the average value is used to calculate the temperature T(t) of the permanent magnet.

6. The temperature monitoring method according to any one of claims 1 to 3, characterized in that: The method further comprises: The set of reference stator voltages u corresponding to different stator currents is pre-assigned to the stator d0 ,u q0 stored in a storage device, and When the motor is running, the set of reference stator voltages u stored in advance is obtained from the storage device. d0 and u q0 The real-time stator current i d (t) and i q (t) Corresponding reference stator voltage u d0 and u q0 .

7. The temperature monitoring method according to claim 3, characterized in that: The following linear Gaussian system is used for state estimation: The state of the linear Gaussian system is The observed quantity is Its satisfaction in B＝[1 0] Among them, A is the state transfer matrix, B is the measurement matrix, g t and e t represent random vector and measurement noise respectively.

8. A temperature monitoring device for monitoring the temperature of a permanent magnet of a permanent magnet synchronous motor, characterized in that: The temperature monitoring device is configured to perform the temperature monitoring method according to any one of claims 1-7.

9. The temperature monitoring device according to claim 8, characterized in that: The temperature monitoring device includes a storage device for storing the flux temperature coefficient β, the reference temperature T0, the reference flux φ0, the reference speed ω0 and the set of reference stator voltages u corresponding to different stator currents of the motor. d0 and u q0 .

10. A monitoring system for monitoring the operation of a permanent magnet synchronous motor, characterized in that: The monitoring system comprises the temperature monitoring device according to claim 8.

11. The monitoring system according to claim 10, characterized in that: The monitoring system further includes a rotation speed measuring device communicatively coupled to the temperature monitoring device, wherein the rotation speed measuring device is used to measure the rotor rotation speed of the motor and input the measured rotor rotation speed to the temperature monitoring device.

12. The monitoring system according to claim 10 or 11, characterized in that: The monitoring system also includes a motor control device communicatively coupled to the temperature monitoring device, the motor control device receiving the temperature of the permanent magnet from the temperature monitoring device and controlling operation of the motor based at least in part on the received temperature of the permanent magnet.

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