CN112234911A - Real-time monitoring method and model for temperature of permanent magnet motor rotor - Google Patents
Real-time monitoring method and model for temperature of permanent magnet motor rotor Download PDFInfo
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- 238000012544 monitoring process Methods 0.000 title claims abstract description 42
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- 238000004804 winding Methods 0.000 claims abstract description 102
- 239000011159 matrix material Substances 0.000 claims abstract description 73
- 238000010521 absorption reaction Methods 0.000 claims abstract description 34
- 230000017525 heat dissipation Effects 0.000 claims abstract description 32
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- 238000012546 transfer Methods 0.000 claims abstract description 30
- 230000002457 bidirectional effect Effects 0.000 claims abstract description 19
- 230000008878 coupling Effects 0.000 claims abstract description 19
- 238000010168 coupling process Methods 0.000 claims abstract description 19
- 238000005859 coupling reaction Methods 0.000 claims abstract description 19
- 239000002826 coolant Substances 0.000 claims description 32
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- 238000010586 diagram Methods 0.000 description 8
- 239000000463 material Substances 0.000 description 7
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- 229910001172 neodymium magnet Inorganic materials 0.000 description 1
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P29/00—Arrangements for regulating or controlling electric motors, appropriate for both AC and DC motors
- H02P29/60—Controlling or determining the temperature of the motor or of the drive
- H02P29/66—Controlling or determining the temperature of the rotor
- H02P29/662—Controlling or determining the temperature of the rotor the rotor having permanent magnets
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P6/00—Arrangements for controlling synchronous motors or other dynamo-electric motors using electronic commutation dependent on the rotor position; Electronic commutators therefor
- H02P6/34—Modelling or simulation for control purposes
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Abstract
The invention relates to a real-time monitoring method and a real-time monitoring model for the temperature of a permanent magnet motor rotor, wherein the method comprises the following steps: discretizing the motor according to the structure of the permanent magnet motor to obtain a plurality of nodes; expressing the heat transfer between adjacent nodes by thermal resistance to obtain a plurality of thermal resistances; connecting a plurality of nodes into a heat network model by using thermal resistance according to a heat transfer path of the permanent magnet motor, and simplifying to obtain a target motor equivalent heat network model, wherein in the target motor equivalent heat network model, the heat absorption or heat dissipation capacity of each node is expressed by using the thermal capacity, and the heat source of each node is expressed by using loss; and calculating a space state matrix of each node in the equivalent heat network model of the target motor, calculating the working temperature of the permanent magnet and the working temperature of the stator winding by combining a loss-temperature bidirectional coupling algorithm, and outputting the working temperature of the permanent magnet. The method can achieve the purpose of monitoring the temperature of the permanent magnet motor in real time and simultaneously ensure the accuracy and reliability of the calculation of the temperature of the permanent magnet.
Description
Technical Field
The invention belongs to the field of new energy electric automobiles, and particularly relates to a real-time monitoring method and a real-time monitoring model for the temperature of a permanent magnet motor rotor.
Background
Permanent magnet motors are gradually becoming the motor technology of choice for electric vehicle drive systems by virtue of their advantages of high power/torque density, high efficiency, compact size, etc. When the motor is operated, the cogging harmonic and the current harmonic can generate significant eddy current loss in the permanent magnet due to the relatively low resistivity of the rare earth magnet. The eddy current loss causes the temperature of the permanent magnet to rise, so that the performance of the permanent magnet can be reduced, even irreversible demagnetization can be caused on part of the permanent magnet in severe cases, and the service life is shortened. Therefore, it is very important to effectively monitor the operating temperature of the permanent magnet in order to ensure that the permanent magnet motor operates within a prescribed temperature range and provide rated power and to avoid demagnetization of the permanent magnet due to high temperature.
At present, there are two main techniques for monitoring the operating temperature of a permanent magnet: non-contact technology and measurement of the magnetic flux of the rotor of an electric machine.
Direct measurement of the permanent magnet temperature by non-contact techniques (e.g., telemetry systems) is complicated and expensive, and these sensors reduce the reliability of the system, making simple replacement of the sensors often difficult in the event of a sensor failure.
The temperature of the permanent magnet is indirectly obtained by measuring the magnetic flux of the motor rotor, and the temperature coefficient of reversible demagnetization of the permanent magnet material is mainly utilized; for example, the temperature coefficient α (Br) of Nd-Fe-B permanent magnets is between-0.05%/k and-0.1%/k. However, this technique requires precise measurement equipment and accurate motor and inverter parameters, and further, motor nonlinearity due to saturation must be considered in modeling, which greatly increases the difficulty of modeling and reduces the accuracy of the model.
In summary, the existing technology for monitoring the operating temperature of the permanent magnet has the problems of low reliability and precision of measuring equipment, high modeling difficulty and low modeling accuracy, and how to effectively monitor the operating temperature of the permanent magnet becomes a technical problem to be solved urgently at present.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a real-time monitoring method and a real-time monitoring model for the temperature of a permanent magnet motor rotor. The technical problem to be solved by the invention is realized by the following technical scheme:
the embodiment of the invention provides a real-time monitoring method for the temperature of a permanent magnet motor rotor, which comprises the following steps:
s1, discretizing the motor according to the structure of the permanent magnet motor to obtain a plurality of nodes;
s2, representing heat transfer between the adjacent nodes by thermal resistance to obtain a plurality of thermal resistances;
s3, connecting a plurality of nodes into a thermal network model by using a plurality of thermal resistances according to a heat transfer path of the permanent magnet motor, and simplifying the connected thermal network model to obtain a target motor equivalent thermal network model, wherein in the target motor equivalent thermal network model, the heat absorption or heat dissipation capacity of each node is represented by heat capacity, and the heat source of each node is represented by loss;
s4, calculating a space state matrix of each node in the target motor equivalent heat network model, calculating the working temperature of a permanent magnet and the working temperature of a stator winding by combining a loss-temperature bidirectional coupling algorithm, and outputting the working temperature of the permanent magnet.
In one embodiment of the present invention, step S3 includes the steps of:
s31, connecting the plurality of nodes into a heat network model by using the plurality of thermal resistances according to a heat transfer path of the permanent magnet motor, and establishing a first motor equivalent heat network model;
s32, simplifying the first motor equivalent heat network model according to the heating and heat dissipation properties inside the permanent magnet motor to obtain the target motor equivalent heat network model, wherein the number of the nodes in the target motor equivalent heat network model is smaller than the number of the nodes in the first motor equivalent heat network model.
In an embodiment of the present invention, the plurality of nodes in the target motor equivalent thermal network model include a motor ambient node, a cooling medium node, a rotor core node, a permanent magnet node, a stator core node, and a stator winding node.
In one embodiment of the present invention, step S4 includes:
s41, calculating loss of each node according to the output instantaneous torque and the output instantaneous speed of the permanent magnet motor and the loss calculation temperature of each node in the target motor equivalent heat network model;
s42, establishing a space state matrix of each node in the target motor equivalent heat network model according to an energy conservation principle;
s43, calculating the working temperature of each node according to the space state matrix, the loss and the loss calculation temperature;
s44, updating the working temperature of each node by using a loss-temperature bidirectional coupling algorithm, and judging a first goodness of fit between the updated working temperature of the permanent magnet and the loss calculation temperature of the permanent magnet and a second goodness of fit between the updated working temperature of the stator winding and the loss calculation temperature of the stator winding;
s45, when the first goodness of fit is less than or equal to the target value or the second goodness of fit is less than or equal to the target value, repeating the steps S41-S44; and when the first goodness of fit is greater than a target value and the second goodness of fit is greater than the target value, outputting the updated working temperature of the permanent magnet.
In one embodiment of the present invention, the spatial state matrix is:
y(t)＝CT(t)+DP(t)
wherein the content of the first and second substances,
the temperature rise rate at the node i, T (t) is a state vector formed by the working temperature of any node in the target motor equivalent heat network model, P (t) is an input vector formed by the heat source loss of any node in the target motor equivalent heat network model, y (t) is an output vector formed by the working temperature of any node in the target motor equivalent heat network model, A is a system matrix, B is an input matrix, C is an output matrix, and D is a feedforward matrix.
In an embodiment of the present invention, when the permanent magnet motor is an interior permanent magnet synchronous motor, the target motor equivalent thermal network model includes: a rotor core node, a permanent magnet node, a stator core node, a stator winding node, a motor surrounding environment node, a cooling medium node, a rotor core heat capacity, a permanent magnet heat capacity, a stator core heat capacity, a stator winding heat capacity, a rotor core loss, a permanent magnet loss, a stator core loss, a stator winding loss, a first heat resistance, a second heat resistance, a third heat resistance, a fourth heat resistance, a fifth heat resistance, and a sixth heat resistance,
the rotor core node is connected with the motor surrounding environment node through the first thermal resistance, the rotor core node is connected with the permanent magnet node through the second thermal resistance, the rotor core node is connected with the stator core node through the third thermal resistance, the stator core node is connected with the stator winding node through the fourth thermal resistance, the stator winding node is connected with the motor surrounding environment node through the fifth thermal resistance, and the stator core node is connected with the cooling medium node through the sixth thermal resistance;
the rotor core heat capacity represents the heat absorption or heat dissipation capacity of rotor core node, the rotor core loss represents the heat source of rotor core node, the permanent magnet heat capacity represents the heat absorption or heat dissipation capacity of permanent magnet node, the permanent magnet loss represents the heat source of permanent magnet node, the stator core heat capacity represents the heat absorption or heat dissipation capacity of stator core node, the stator core loss represents the heat source of stator core node, the stator winding heat capacity represents the heat absorption or heat dissipation capacity of stator winding node, the stator winding loss represents the heat source of stator winding node.
In one embodiment of the present invention, when the permanent magnet motor is an interior permanent magnet synchronous motor, the spatial state matrix is:
y(t)＝CT(t)+DP(t)
since the temperature of the motor ambient node (a) and the temperature of the cooling medium node (c) change to 0 over time, then:
D＝0
wherein the content of the first and second substances,
is the temperature rise rate at a node i, T (t) is a state vector formed by the working temperature of any node in the target motor equivalent heat network model, P (t) is an input vector formed by the heat source loss of any node in the target motor equivalent heat network model, y (t) is an output vector formed by the working temperature of any node in the target motor equivalent heat network model, A is a system matrix, B is an input matrix, C is an output matrix, D is a feedforward matrix, a is a node of the surrounding environment of the motor, C is a cooling medium node, R is a rotor core node, m is a permanent magnet node, s is a stator core node, w is a stator winding node, R (t) is a stator core nodea，rIs a first thermal resistance, Rr，mIs the second thermal resistance, Rr，sIs a third thermal resistance, Rs，wIs a fourth thermal resistance, Ra，wIs a fifth thermal resistance, Rc，sIs a sixth thermal resistance, CrFor heat capacity of rotor core, CmIs a permanent magnet heatC of containersFor stator core heat capacity, CwIs the stator winding heat capacity.
In an embodiment of the present invention, when the permanent magnet motor is a surface-mount permanent magnet synchronous motor, the target motor equivalent thermal network model includes: a rotor core node, a permanent magnet node, a stator core node, a stator winding node, a motor surrounding environment node, a cooling medium node, a rotor core heat capacity, a permanent magnet heat capacity, a stator core heat capacity, a stator winding heat capacity, a rotor core loss, a permanent magnet loss, a stator core loss, a stator winding loss, a first heat resistance, a second heat resistance, a third heat resistance, a fourth heat resistance, a fifth heat resistance, and a sixth heat resistance,
the rotor core node is connected with the motor surrounding environment node through the first thermal resistance, the rotor core node is connected with the permanent magnet node through the second thermal resistance, the permanent magnet node is connected with the stator core node through the third thermal resistance, the stator core node is connected with the stator winding node through the fourth thermal resistance, the stator winding node is connected with the motor surrounding environment node through the fifth thermal resistance, and the stator core node is connected with the cooling medium node through the sixth thermal resistance;
the rotor core heat capacity represents the heat absorption or heat dissipation capacity of rotor core node, the rotor core loss represents the heat source of rotor core node, the permanent magnet heat capacity represents the heat absorption or heat dissipation capacity of permanent magnet node, the permanent magnet loss represents the heat source of permanent magnet node, the stator core heat capacity represents the heat absorption or heat dissipation capacity of stator core node, the stator core loss represents the heat source of stator core node, the stator winding heat capacity represents the heat absorption or heat dissipation capacity of stator winding node, the stator winding loss represents the heat source of stator winding node.
In an embodiment of the present invention, when the permanent magnet motor is a surface-mount permanent magnet synchronous motor, the spatial state matrix is:
y(t)＝CT(t)+DP(t)
since the temperature of the motor ambient node (a) and the temperature of the cooling medium node (c) change to 0 over time, then:
D＝0
wherein the content of the first and second substances,
is the temperature rise rate at a node i, T (t) is a state vector formed by the working temperature of any node in the target motor equivalent heat network model, P (t) is an input vector formed by the heat source loss of any node in the target motor equivalent heat network model, y (t) is an output vector formed by the working temperature of any node in the target motor equivalent heat network model, A is a system matrix, B is an input matrix, C is an output matrix, D is a feedforward matrix, aIs a node of the surrounding environment of the motor, c is a node of a cooling medium, R is a node of a rotor core, m is a node of a permanent magnet, s is a node of a stator core, w is a node of a stator winding, Ra，rIs a first thermal resistance, Rr，mIs the second thermal resistance, Rm，sIs a third thermal resistance, Rs，wIs a fourth thermal resistance, Ra，wIs a fifth thermal resistance, Rc，sIs a sixth thermal resistance, CrFor heat capacity of rotor core, CmIs the heat capacity of a permanent magnet, CsFor stator core heat capacity, CwIs the stator winding heat capacity.
Another embodiment of the present invention provides a real-time monitoring model of the temperature of a permanent magnet of a rotor of a permanent magnet motor, including:
the node acquisition module is used for carrying out discretization processing on the motor according to the structure of the permanent magnet motor to obtain a plurality of nodes;
the node circuitization module is used for expressing the heat transfer between the adjacent nodes by thermal resistance to obtain a plurality of thermal resistances;
the model establishing module is used for connecting a plurality of nodes into a heat network model by using a plurality of thermal resistances according to a heat transfer path of the permanent magnet motor, and simplifying the connected heat network model to obtain a target motor equivalent heat network model, wherein in the target motor equivalent heat network model, the heat absorption or heat dissipation capacity of each node is expressed by heat capacity, and the heat source of each node is expressed by loss;
and the temperature acquisition module is used for calculating a space state matrix of each node in the target motor equivalent heat network model, calculating the working temperature of the permanent magnet and the working temperature of the stator winding by combining a loss-temperature bidirectional coupling algorithm, and outputting the working temperature of the permanent magnet.
Compared with the prior art, the invention has the beneficial effects that:
the method for monitoring the temperature of the permanent magnet motor rotor in real time does not need any additional detection equipment, can greatly shorten the calculation time through a simplified equivalent heat network model of the target motor, and achieves the aim of quickly monitoring the temperature of the permanent magnet in real time; meanwhile, by introducing a loss-temperature bidirectional coupling algorithm, the influence of the temperature characteristic of the material on the loss is considered, and the accuracy of the equivalent heat network model for predicting the temperature is greatly improved; therefore, the real-time monitoring method can achieve the purposes of monitoring the temperature of the permanent magnet of the motor rotor in real time, simultaneously ensuring the accuracy and reliability of the temperature calculation of the rotor permanent magnet, ensuring that the permanent magnet motor runs in a specified temperature range and avoiding permanent demagnetization of the permanent magnet caused by overhigh temperature of the permanent magnet.
Drawings
Fig. 1 is a schematic flow chart of a method for monitoring the temperature of a permanent magnet motor rotor in real time according to an embodiment of the present invention;
fig. 2 is a schematic flow chart of another method for monitoring the temperature of a permanent magnet motor rotor in real time according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of calculating the operating temperature of a permanent magnet by using a loss-temperature bidirectional coupling algorithm according to an embodiment of the present invention;
fig. 4 is a schematic diagram of an equivalent thermal network model of a target motor of an interior permanent magnet synchronous motor according to an embodiment of the present invention;
fig. 5 is a schematic diagram of a target motor equivalent thermal network model of a surface-mounted permanent magnet synchronous motor according to an embodiment of the present invention;
fig. 6 is a schematic structural diagram of a model for monitoring the temperature of a permanent magnet motor rotor in real time according to an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to specific examples, but the embodiments of the present invention are not limited thereto.
Example one
Referring to fig. 1 and fig. 2, fig. 1 is a schematic flow chart of a method for monitoring temperature of a permanent magnet motor rotor in real time according to an embodiment of the present invention, and fig. 2 is a schematic flow chart of another method for monitoring temperature of a permanent magnet motor rotor in real time according to an embodiment of the present invention. The real-time monitoring method comprises the following steps:
and S1, discretizing the motor according to the structure of the permanent magnet motor to obtain a plurality of nodes.
Specifically, according to the structure of the permanent magnet motor, discretization processing is carried out on different component structures in the motor, each component is represented in a node form, a plurality of nodes are obtained, and each node is regarded as a unit with lumped parameters. For example, for an interior permanent magnet motor, different component structures in the motor can be divided into several nodes, namely, the environment around the motor, a cooling medium, a casing, an end cover, a stator core, a stator winding, a rotor core and a permanent magnet after discretization processing, and each node is a unit with lumped parameters.
And S2, expressing the heat transfer between the adjacent nodes as thermal resistance, and obtaining a plurality of thermal resistances.
It can be understood that, after dividing different component structures of the motor into a plurality of nodes, simulating a circuit model, the heat transfer between adjacent nodes is simulated by using the thermal resistance, so that a plurality of thermal resistances are obtained. For example, for a node in an interior permanent magnet machine: the heat transfer between the stator core and the stator winding is expressed by element thermal resistance R in the circuit, and 1 thermal resistance is obtained.
And S3, connecting the nodes into a heat network model by using a plurality of thermal resistances according to the heat transfer path of the permanent magnet motor, and simplifying the connected heat network model to obtain the equivalent heat network model of the target motor. The method specifically comprises the following steps:
and S31, connecting the plurality of nodes by a plurality of thermal resistances according to the heat transfer path of the permanent magnet motor, and establishing an equivalent thermal network model of the first motor.
Specifically, after obtaining a plurality of thermal resistances, sequentially connecting a plurality of nodes according to the heat transfer path of the permanent magnet in the motor, wherein the connection mode is as follows: connecting two nodes which transfer heat with each other sequentially through thermal resistance to form a first motor equivalent heat network model; meanwhile, in the first motor equivalent heat network model, for each node with the working temperature changing along with the time, the heat absorption or heat dissipation capacity of the node is represented by the element heat capacity C in the circuit. Furthermore, the number of nodes in the established first motor equivalent thermal network model is large, the first motor equivalent thermal network model is a relatively complex thermal network model, and the complex temperature field of the motor can be effectively represented.
Specifically, in the first motor equivalent thermal network model, due to the difference in heat transfer modes between adjacent nodes, the thermal resistance element is subdivided into thermal conduction thermal resistance, convective heat dissipation thermal resistance, radiative heat dissipation thermal resistance, and contact thermal resistance.
Further, the heat capacity of each component structure and the heat resistance among the component structures in the first motor equivalent heat network model can be calculated by using an equivalence method.
S32, simplifying the first motor equivalent heat network model according to the heating and heat dissipation properties inside the permanent magnet motor to obtain a target motor equivalent heat network model, wherein the number of nodes in the target motor equivalent heat network model is smaller than that of the nodes in the first motor equivalent heat network model.
In order to shorten the calculation time and achieve the purpose of quickly estimating the temperature of the permanent magnet in real time, the internal heating and heat dissipation characteristics of the permanent magnet motor are comprehensively considered, and therefore 6 nodes in the divided nodes are reserved. Then, by analogy with a circuit resistor series-parallel theory, a complex first motor equivalent thermal network model is moderately simplified to obtain a target equivalent thermal network model, wherein the number of nodes in the target equivalent thermal network model is smaller than the number of nodes in the first motor equivalent thermal network model.
Specifically, after the reduced number of nodes are obtained, thermal resistances in the target motor equivalent heat network model and heat capacities and heat source losses of all parts are determined, all the nodes are sequentially connected by the thermal resistances according to the motor structure and a heat transfer path, and the simplified target motor equivalent heat network model is designed and built.
In the embodiment, six nodes of the surrounding environment of the motor, the cooling medium, the rotor core, the permanent magnet, the stator core and the stator winding are reserved; the working temperature of the 4 nodes of the rotor core, the permanent magnet, the stator core and the stator winding changes along with time and is 4 heat sources, and each heat source has corresponding heat capacity and loss; the working temperature of the surrounding environment of the motor and the cooling medium does not change along with time, and the working temperature does not have corresponding heat capacity and loss; there is a corresponding thermal resistance between the two nodes that transfer heat between each other. Then, according to the structure of the motor and the heat transfer path between the nodes, the 6 nodes of the motor surrounding environment, the cooling medium, the rotor core, the permanent magnet, the stator core and the stator winding are connected by thermal resistance to form a target motor equivalent heat network model with four heat sources, in the target motor equivalent heat network model, the thermal capacity represents the heat absorption or heat dissipation capacity of each node, and the loss represents the heat source of each node.
S4, calculating a space state matrix of each node in the target motor equivalent heat network model, calculating the working temperature of the permanent magnet and the working temperature of the stator winding by combining a loss-temperature bidirectional coupling algorithm, and outputting the working temperature of the permanent magnet.
In this embodiment, the calculation of the loss and the operating temperature are both for the heat source node.
Referring to fig. 2 and fig. 3, fig. 3 is a schematic diagram of calculating the operating temperature of the permanent magnet by using a loss-temperature bidirectional coupling algorithm according to an embodiment of the present invention. Step S4 specifically includes the steps of:
and S41, calculating the loss of each node according to the output instantaneous torque, the output instantaneous speed and the loss calculation temperature of each node in the equivalent thermal network model of the target motor.
First, initial conditions are set: initial temperature T of each node in the motorrefI.e. calculating the temperature for the loss of each node, including the initial temperature T of the rotor corer0Permanent magnet initial temperature Tm0Initial temperature T of stator cores0Initial temperature T of stator windingw0Ambient temperature T of the motoraAnd the temperature T of the cooling mediumc。
Then, the output instantaneous torque, the output instantaneous speed and the initial temperature of each node (namely the initial temperature T of the rotor core) of the permanent magnet motor are calculated according to the output instantaneous torque, the output instantaneous speed and the initial temperature of each noder0Permanent magnet initial temperature Tm0Initial temperature T of stator cores0Initial temperature T of stator windingw0) Calculating the loss of each node by using an analytical method and a finite element method to obtain the rotor coreHeat loss P ofrHeat loss P of permanent magnetmHeat loss P of stator coresHeat loss P of stator windingw。
And S42, establishing a space state matrix of each node in the target motor equivalent thermal network model according to an energy conservation principle.
Firstly, according to the principle of energy conservation, the transient heat balance equation at any node i in the target motor equivalent heat network model is as follows:
wherein, Ci＝ρiciViIs the net heat flow at node i, PiIs the loss at node i, ρiIs the density of the material at node i, ciIs the specific heat capacity of the material at node i, ViIs the volume of material at node i, TiIs the temperature at node i, t is the time;
is the rate of temperature rise at node i, Ri，jIs the thermal resistance between the nodes.
In order to more conveniently solve the time domain response of the state variables of the heat balance equation so as to obtain the temperature change of the permanent magnet and the winding, the above formula is expressed as the following space state matrix by adopting a space state method:
y(t)＝CT(t)+DP(t)
wherein the content of the first and second substances,
is the temperature rise rate at the node i, T (t) is a state vector formed by the working temperature of any node in the target motor equivalent heat network model, P (t) is an input vector formed by the heat source loss of any node in the target motor equivalent heat network model, and y (t) is a targetAnd marking an output vector formed by the working temperature of any node in the equivalent heat network model of the motor, wherein A is a system matrix, B is an input matrix, C is an output matrix, and D is a feedforward matrix.
And S43, calculating the working temperature of each node according to the space state matrix, the loss and the initial temperature.
Specifically, the temperature, i.e., the initial temperature T, is calculated using the loss of each node and the loss of each node in step S41refThe space state matrix of the formula (2) is solved, and the working temperature of each node can be obtained through calculation.
And S44, updating the working temperature of each node by using a loss-temperature bidirectional coupling algorithm, and judging a first goodness of fit between the updated working temperature of the permanent magnet and the loss calculation temperature of the permanent magnet and a second goodness of fit between the updated working temperature of the stator winding and the loss calculation temperature of the stator winding.
In this embodiment, for the problem that the temperature characteristic of the material affects the loss in the temperature rise calculation process, temperature feedback is added to the target motor equivalent thermal network model, and a loss-temperature bidirectional coupling calculation method is adopted to realize feedback of loss-temperature information and perform iterative thermal calculation.
Specifically, after the working temperature of each node is calculated in step S43, the working temperature of each node is updated, and then it is determined whether the updated working temperature of the permanent magnet matches the loss calculation temperature of the permanent magnet, that is, a first degree of matching, and it is determined whether the updated working temperature of the stator winding matches the loss calculation temperature of the stator winding, that is, a second degree of matching; this step is to determine whether the solved operating temperature converges.
It can be understood that after the working temperature of each node is calculated by using the initial temperature of each node, the obtained working temperature of the permanent magnet and the working temperature of the stator winding are respectively compared with the corresponding initial temperatures; and after the working temperature of each node is calculated again by using the updated working temperature of each node, comparing the recalculated working temperature of the permanent magnet and the recalculated working temperature of the stator winding with the updated corresponding working temperature respectively.
S45, when the first goodness of fit is less than or equal to the target value or the second goodness of fit is less than or equal to the target value, repeating the steps S41-S44; and when the first goodness of fit is greater than the target value and the second goodness of fit is greater than the target value, outputting the updated working temperature of the permanent magnet.
In this embodiment, the target value may be greater than or equal to 95%.
Specifically, when the first goodness of fit is equal to or less than 95% or the second goodness of fit is equal to or less than 95%, repeating steps S41-S44, recalculating the loss of each heat source node by using the updated working temperature of each node, solving the space state matrix again by using the recalculated loss and the updated working temperature, obtaining the working temperature of each node again, comparing the obtained working temperature of the permanent magnet and the stator winding with the updated working temperature of the permanent magnet and the stator winding, and judging the goodness of fit.
When the first goodness of fit is greater than 95% and the second goodness of fit is greater than 95%, the solution of the space state matrix is converged, and then the working temperature of the permanent magnet is output to monitor whether the permanent magnet works in a safe temperature range.
In this embodiment, the goodness of fit may be different according to the calculation time of the solver and the requirement on the accuracy of the model; the higher the goodness of fit is, the longer the iterative computation cycle is, the longer the computation time is, but the higher the model accuracy is; and vice versa.
The method for monitoring the temperature of the permanent magnet motor rotor in real time does not need any additional detection equipment, can greatly shorten the calculation time through a simplified equivalent heat network model of the target motor, and achieves the purpose of monitoring the temperature of the permanent magnet rapidly in real time; meanwhile, by introducing a loss-temperature bidirectional coupling algorithm, the influence of the temperature characteristic of the material on the loss is considered, and the accuracy of the equivalent heat network model for predicting the temperature is greatly improved; therefore, the real-time monitoring method can achieve the purposes of monitoring the temperature of the permanent magnet of the motor in real time, simultaneously ensuring the accuracy and reliability of the calculation of the temperature of the permanent magnet, ensuring that the permanent magnet motor operates in a specified temperature range and avoiding permanent demagnetization of the permanent magnet caused by overhigh temperature of the permanent magnet.
Example two
On the basis of the first embodiment, the present embodiment is described by taking a real-time monitoring method of the temperature of the permanent magnet of the rotor of the internal permanent magnet synchronous motor as an example.
Referring to fig. 4, fig. 4 is a schematic diagram of a target motor equivalent thermal network model of an interior permanent magnet synchronous motor according to an embodiment of the present invention.
For the built-in permanent magnet motor, heat generated by permanent magnet loss firstly passes through a rotor core and then is transferred to a stator core, and finally the heat is dissipated through a cooling medium, so that the real-time monitoring method for the temperature of the permanent magnet of the built-in permanent magnet synchronous motor rotor comprises the following steps:
and S1, discretizing the motor according to the structure of the permanent magnet motor to obtain a plurality of nodes.
And S2, expressing the heat transfer between the adjacent nodes as thermal resistance, and obtaining a plurality of thermal resistances.
S3, connecting the plurality of nodes into a heat network model by using a plurality of thermal resistances according to the heat transfer path of the permanent magnet motor, and simplifying the connected heat network model to obtain a target motor equivalent heat network model, wherein in the target motor equivalent heat network model, the heat absorption or heat dissipation capacity of each node is expressed by heat capacity, and the heat source of each node is expressed by loss.
In this embodiment, the simplified target motor equivalent thermal network model of the interior permanent magnet synchronous motor includes a rotor core node r, a permanent magnet node m, a stator core node s, a stator winding node w, a motor surrounding environment node a, a cooling medium node C, and a rotor core heat capacity CrPermanent magnet heat capacity CmStator core heat capacity CsStator winding heat capacity CwRotor core loss PrPermanent magnet loss PmStator core loss PsStator winding loss PwFirst thermal resistance Ra，rA second thermal resistance Rr，mA third thermal resistance Rr，sFourth thermal resistance Rs，wFifth thermal resistance Ra，wSixth thermal resistance Rc，s(ii) a The number of the rotor core nodes r, the number of the permanent magnet nodes m, the number of the stator core nodes s, the number of the stator winding nodes w, the number of the motor surrounding environment nodes a and the number of the cooling medium nodes c are 6, and in the 6 nodes, the number of the rotor core nodes r, the number of the permanent magnet nodes m, the number of the stator core nodes s and the number of the stator winding nodes w are heat sources.
Specifically, a rotor core node R and a motor surrounding environment node a pass through a first thermal resistance Ra，rThe rotor core node R and the permanent magnet node m are connected through a second thermal resistance Rr，mThe rotor core node R and the stator core node s are connected through a third thermal resistance Rr，sThe stator core node s and the stator winding node w are connected through a fourth thermal resistance Rs，wThe connection is realized, and the stator winding node w and the motor surrounding environment node a are connected through a fifth thermal resistance Ra，wThe stator core node s and the cooling medium node c are connected through a sixth thermal resistance Rc，sConnecting; rotor core heat capacity CrRepresenting the heat absorption or heat dissipation capacity of the rotor core node r and the loss P of the rotor corerHeat source representing rotor core node r, permanent magnet heat capacity CmRepresenting the heat absorption or heat dissipation capacity of the permanent magnet node m, the permanent magnet loss PmHeat source representing permanent magnet node m, stator core heat capacity CsRepresenting the heat absorption or heat dissipation capacity of the stator core node s and the stator core loss PsHeat source representing stator core node s, stator winding heat capacity CwShowing the heat absorption or heat dissipation capacity of the stator winding node w, the stator winding loss PwRepresenting the heat source at stator winding node w.
S4, calculating a space state matrix of each node in the target motor equivalent heat network model, calculating the working temperature of the permanent magnet and the working temperature of the stator winding by combining a loss-temperature bidirectional coupling algorithm, and outputting the working temperature of the permanent magnet.
And S41, calculating the loss of each node according to the output instantaneous torque, the output instantaneous speed and the loss calculation temperature of each node in the equivalent thermal network model of the target motor.
And S42, establishing a space state matrix of each node in the target motor equivalent thermal network model according to an energy conservation principle.
Specifically, when the permanent magnet motor is a interior permanent magnet synchronous motor, the spatial state matrix is:
y(t)＝CT(t)+DP(t)
wherein the content of the first and second substances,
the temperature rise rate at the node i, T (t) is a state vector formed by the working temperature of any node in the target motor equivalent heat network model, P (t) is an input vector formed by the heat source loss of any node in the target motor equivalent heat network model, y (t) is an output vector formed by the working temperature of any node in the target motor equivalent heat network model, A is a system matrix, B is an input matrix, C is an output matrix, and D is a feedforward matrix.
When the simplified target motor equivalent heat network model comprises a cooling medium and a motor surrounding environment node, the temperature of the two nodes changes 0 along with time. Therefore, the column vector of the two nodes in the matrix a is 0, and each matrix in the spatial state matrix is expressed as follows:
D＝0
wherein R isa，rIs a first thermal resistance, Rr，mIs the second thermal resistance, Rr，sIs a third thermal resistance, Rs，wIs a fourth thermal resistance, Ra，wIs a fifth thermal resistance, Rc，sIs a sixth thermal resistance, CrFor heat capacity of rotor core, CmIs the heat capacity of a permanent magnet, CsFor stator core heat capacity, CwIs the stator winding heat capacity.
And S43, calculating the working temperature of each node according to the space state matrix, the loss and the initial temperature.
And S44, updating the working temperature of each node by using a loss-temperature bidirectional coupling algorithm, and judging a first goodness of fit between the updated working temperature of the permanent magnet and the loss calculation temperature of the permanent magnet and a second goodness of fit between the updated working temperature of the stator winding and the loss calculation temperature of the stator winding.
S45, when the first goodness of fit is less than or equal to the target value or the second goodness of fit is less than or equal to the target value, repeating the steps S41-S44; and when the first goodness of fit is greater than the target value and the second goodness of fit is greater than the target value, outputting the updated working temperature of the permanent magnet.
EXAMPLE III
On the basis of the first embodiment, the present embodiment takes a real-time monitoring method of the temperature of the permanent magnet of the rotor of the surface-mounted permanent magnet synchronous motor as an example for explanation.
Referring to fig. 5, fig. 5 is a schematic diagram of a target motor equivalent thermal network model of a surface-mount permanent magnet synchronous motor according to an embodiment of the present invention.
The unique structure of the surface-mounted permanent magnet motor and the interior permanent magnet motor is different from the position of the permanent magnet in the rotor, which also influences the heat transfer path of the permanent magnet. For surface-mounted permanent magnet motors, permanent magnet losses are transferred directly to the cooling medium through the stator core. Therefore, the real-time monitoring method for the temperature of the permanent magnet of the rotor of the permanent magnet synchronous motor comprises the following steps:
and S1, discretizing the motor according to the structure of the permanent magnet motor to obtain a plurality of nodes.
And S2, expressing the heat transfer between the adjacent nodes as thermal resistance, and obtaining a plurality of thermal resistances.
S3, connecting the plurality of nodes into a heat network model by using a plurality of thermal resistances according to the heat transfer path of the permanent magnet motor, and simplifying the connected heat network model to obtain a target motor equivalent heat network model, wherein in the target motor equivalent heat network model, the heat absorption or heat dissipation capacity of each node is expressed by heat capacity, and the heat source of each node is expressed by loss.
In this embodiment, the simplified target motor equivalent thermal network model of the surface-mounted permanent magnet synchronous motor includes: rotor core node r, permanent magnet node m, stator core node s, stator winding node w, motor surrounding environment node a, cooling medium node C and rotor core heat capacity CrPermanent magnet heat capacity CmStator core heat capacity CsStator winding heat capacity CwRotor core loss PrPermanent magnet loss PmStator core loss PsStator winding loss PwFirst thermal resistance Ra，rA second thermal resistance Rr，mA third thermal resistance Rm，sFourth thermal resistance Rs，wFifth thermal resistance Ra，wSixth thermal resistance Rc，s。。
Specifically, a rotor core node R and a motor surrounding environment node a pass through a first thermal resistance Ra，rThe rotor core node R and the permanent magnet node m are connected through a second thermal resistance Rr，mThe permanent magnet node m and the stator core node s are connected through a third thermal resistance Rm，sThe stator core node s and the stator winding node w are connected through a fourth thermal resistance Rs，wThe connection is realized, and the stator winding node w and the motor surrounding environment node a are connected through a fifth thermal resistance Ra，wThe stator core node s and the cooling medium node c are connected through a sixth thermal resistance Rc，sConnecting;rotor core heat capacity CrRepresenting the heat absorption or heat dissipation capacity of the rotor core node r and the loss P of the rotor corerHeat source representing rotor core node r, permanent magnet heat capacity CmRepresenting the heat absorption or heat dissipation capacity of the permanent magnet node m, the permanent magnet loss PmHeat source representing permanent magnet node m, stator core heat capacity CsRepresenting the heat absorption or heat dissipation capacity of the stator core node s and the stator core loss PsHeat source representing stator core node s, stator winding heat capacity CwShowing the heat absorption or heat dissipation capacity of the stator winding node w, the stator winding loss PwRepresenting the heat source at stator winding node w.
S4, calculating a space state matrix of each node in the target motor equivalent heat network model, calculating the working temperature of the permanent magnet and the working temperature of the stator winding by combining a loss-temperature bidirectional coupling algorithm, and outputting the working temperature of the permanent magnet.
And S41, calculating the temperature according to the output instantaneous torque and the output instantaneous speed of the permanent magnet motor and the loss of each node in the equivalent heat network model of the target motor, and then calculating the loss of each node.
And S42, establishing a space state matrix of each node in the target motor equivalent thermal network model according to an energy conservation principle.
When the permanent magnet motor is a surface-mounted permanent magnet synchronous motor, the space state matrix is as follows:
y(t)＝CT(t)+DP(t)
wherein the content of the first and second substances,
is the temperature rise rate at a node i, T (t) is a state vector formed by the working temperature of any node in the target motor equivalent heat network model, P (t) is an input vector formed by the heat source loss of any node in the target motor equivalent heat network model, y (t) is an output vector formed by the working temperature of any node in the target motor equivalent heat network model, A is a system momentThe matrix, B is the input matrix, C is the output matrix, and D is the feedforward matrix.
When the simplified target motor equivalent heat network model comprises a cooling medium and a motor surrounding environment node, the temperature of the two nodes changes 0 along with time. Therefore, the column vector of the two nodes in the matrix a is 0, and each matrix in the spatial state matrix is expressed as follows:
D＝0
wherein R isa，rIs a first thermal resistance, Rr，mIs the second thermal resistance, Rm，sIs a third thermal resistance, Rs，wIs a fourth thermal resistance, Ra，wIs a fifth thermal resistance, Rc，sIs a sixth thermal resistance, CrFor heat capacity of rotor core, CmIs the heat capacity of a permanent magnet, CsFor stator core heat capacity, CwIs the stator winding heat capacity.
And S43, calculating the working temperature of each node according to the space state matrix, the loss and the initial temperature.
And S44, updating the working temperature of each node by using a loss-temperature bidirectional coupling algorithm, and judging a first goodness of fit between the updated working temperature of the permanent magnet and the loss calculation temperature of the permanent magnet and a second goodness of fit between the updated working temperature of the stator winding and the loss calculation temperature of the stator winding.
S45, when the first goodness of fit is less than or equal to the target value or the second goodness of fit is less than or equal to the target value, repeating the steps S41-S44; and when the first goodness of fit is greater than the target value and the second goodness of fit is greater than the target value, outputting the updated working temperature of the permanent magnet.
Example four
On the basis of the first embodiment, please refer to fig. 6, and fig. 6 is a schematic structural diagram of a model for monitoring the temperature of a permanent magnet of a rotor of a permanent magnet motor in real time according to an embodiment of the present invention. The real-time monitoring model comprises:
the node obtaining module 601 is configured to perform discretization processing on the motor according to the structure of the permanent magnet motor to obtain a plurality of nodes. The node circuitization module 602 is configured to represent heat transfer between adjacent nodes as thermal resistances, resulting in a plurality of thermal resistances. The model establishing module 603 is configured to connect the plurality of nodes to form a thermal network model by using a plurality of thermal resistances according to a heat transfer path of the permanent magnet motor, and simplify the connected thermal network model to obtain an equivalent thermal network model of the target motor, where in the equivalent thermal network model of the target motor, a heat absorption or heat dissipation capacity of each node is expressed by a heat capacity, and a heat source of each node is expressed by a loss. And the temperature obtaining module 604 is configured to calculate a space state matrix of each node in the target motor equivalent thermal network model, calculate a permanent magnet working temperature and a stator winding working temperature by combining a loss-temperature bidirectional coupling algorithm, and output the permanent magnet working temperature.
For the specific implementation process of each module, please refer to embodiment one, which is not described in detail in this embodiment.
The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. For those skilled in the art to which the invention pertains, several simple deductions or substitutions can be made without departing from the spirit of the invention, and all shall be considered as belonging to the protection scope of the invention.
Claims (10)
1. A real-time monitoring method for the temperature of a permanent magnet motor rotor is characterized by comprising the following steps:
s1, discretizing the motor according to the structure of the permanent magnet motor to obtain a plurality of nodes;
s2, representing heat transfer between the adjacent nodes by thermal resistance to obtain a plurality of thermal resistances;
s3, connecting a plurality of nodes into a thermal network model by using a plurality of thermal resistances according to a heat transfer path of the permanent magnet motor, and simplifying the connected thermal network model to obtain a target motor equivalent thermal network model, wherein in the target motor equivalent thermal network model, the heat absorption or heat dissipation capacity of each node is represented by heat capacity, and the heat source of each node is represented by loss;
s4, calculating a space state matrix of each node in the target motor equivalent heat network model, calculating the working temperature of a permanent magnet and the working temperature of a stator winding by combining a loss-temperature bidirectional coupling algorithm, and outputting the working temperature of the permanent magnet.
2. The method for monitoring the temperature of the permanent magnet motor rotor in real time according to claim 1, wherein the step S3 comprises the steps of:
s31, connecting the plurality of nodes by the plurality of thermal resistances according to a heat transfer path of the permanent magnet motor, and establishing a first motor equivalent heat network model;
s32, simplifying the first motor equivalent heat network model according to the heating and heat dissipation properties inside the permanent magnet motor to obtain the target motor equivalent heat network model, wherein the number of the nodes in the target motor equivalent heat network model is smaller than the number of the nodes in the first motor equivalent heat network model.
3. The method of claim 1, wherein the plurality of nodes in the target motor equivalent thermal network model include a motor ambient node, a cooling medium node, a rotor core node, a permanent magnet node, a stator core node, and a stator winding node.
4. The method for monitoring the temperature of the permanent magnet motor rotor in real time according to claim 1, wherein the step S4 comprises the following steps:
s41, calculating loss of each node according to the output instantaneous torque and the output instantaneous speed of the permanent magnet motor and the loss calculation temperature of each node in the target motor equivalent heat network model;
s42, establishing a space state matrix of each node in the target motor equivalent heat network model according to an energy conservation principle;
s43, calculating the working temperature of each node according to the space state matrix, the loss and the loss calculation temperature;
s44, updating the working temperature of each node by using a loss-temperature bidirectional coupling algorithm, and judging a first goodness of fit between the updated working temperature of the permanent magnet and the loss calculation temperature of the permanent magnet and a second goodness of fit between the updated working temperature of the stator winding and the loss calculation temperature of the stator winding;
s45, when the first goodness of fit is less than or equal to the target value or the second goodness of fit is less than or equal to the target value, repeating the steps S41-S44; and when the first goodness of fit is greater than a target value and the second goodness of fit is greater than the target value, outputting the updated working temperature of the permanent magnet.
5. The method for monitoring the temperature of the permanent magnet motor rotor according to claim 1, wherein the spatial state matrix is:
y(t)＝CT(t)+DP(t)
wherein the content of the first and second substances,
the temperature rise rate at the node i, T (t) is a state vector formed by the working temperature of any node in the target motor equivalent heat network model, P (t) is an input vector formed by the heat source loss of any node in the target motor equivalent heat network model, y (t) is an output vector formed by the working temperature of any node in the target motor equivalent heat network model, A is a system matrix, B is an input matrix, C is an output matrix, and D is a feedforward matrix.
6. The method for monitoring the temperature of the permanent magnet motor rotor in real time according to claim 1, wherein when the permanent magnet motor is an interior permanent magnet synchronous motor, the target motor equivalent thermal network model comprises: rotor core node (r), permanent magnet node (m), stator core node(s), stator winding node (w), motor surrounding environment node (a), cooling medium node (C), rotor core heat capacity (C)r) Permanent magnet heat capacity (C)m) Stator core heat capacity (C)s) Stator winding heat capacity (C)w) Rotor core loss (P)r) Permanent magnet loss (P)m) Stator core loss (P)s) Stator winding loss (P)w) First thermal resistance (R)a,r) Second thermal resistance (R)r,m) Third thermal resistance (R)r,s) Fourth thermal resistance (R)s,w) Fifth thermal resistance (R)a,w) Sixth thermal resistance (R)c,s) Wherein, in the step (A),
the rotor core node (R) and the motor surrounding environment node (a) are connected through the first thermal resistance (R)a,r) Connected, the rotor core node (R) and the permanent magnet node (m) pass through the second thermal resistance (R)r,m) Connected, the rotor core node (R) and the stator core node(s) passing through the third thermal resistance (R)r,s) Connected, the stator core node(s) and the stator winding node (w) pass through the secondFour thermal resistance (R)s,w) Connected, the stator winding node (w) and the motor surrounding node (a) are connected through a fifth thermal resistance (R)a,w) Connected, the stator core node(s) and the cooling medium node (c) passing through the sixth thermal resistance (R)c,s) Connecting;
the rotor core heat capacity (C)r) Representing the heat absorption or dissipation capacity of the rotor core node (r), the rotor core loss (P)r) A heat source representing a node (r) of the rotor core, the permanent magnet heat capacity (C)m) Representing the heat absorption or dissipation capacity of the permanent magnet node (m), the permanent magnet losses (P)m) A heat source representing the permanent magnet node (m), the stator core heat capacity (C)s) Representing the heat absorption or dissipation capacity of the stator core node(s), the stator core loss (P)s) A heat source representing a node(s) of the stator core, the stator winding heat capacity (C)w) Representing the heat absorption or dissipation capacity of the stator winding nodes (w), the stator winding losses (P)w) Represents a heat source of the stator winding node (w).
7. The method for monitoring the temperature of the permanent magnet motor rotor according to claim 6, wherein when the permanent magnet motor is an interior permanent magnet synchronous motor, the spatial state matrix is:
y(t)＝CT(t)+DP(t)
since the temperature of the motor ambient node (a) and the temperature of the cooling medium node (c) change to 0 over time, then:
D＝0
wherein the content of the first and second substances,
is the temperature rise rate at a node i, T (t) is a state vector formed by the working temperature of any node in the target motor equivalent heat network model, P (t) is an input vector formed by the heat source loss of any node in the target motor equivalent heat network model, y (t) is an output vector formed by the working temperature of any node in the target motor equivalent heat network model, A is a system matrix, B is an input matrix, C is an output matrix, D is a feedforward matrix, a is a node of the surrounding environment of the motor, C is a cooling medium node, R is a rotor core node, m is a permanent magnet node, s is a stator core node, w is a stator winding node, R (t) is a stator core nodea,rIs a first thermal resistance, Rr,mIs the second thermal resistance, Rr,sIs a third thermal resistance, Rs,wIs a fourth thermal resistance, Ra,wIs a fifth thermal resistance, Rc,sIs a sixth thermal resistance, CrFor heat capacity of rotor core, CmIs the heat capacity of a permanent magnet, CsFor stator core heat capacity, CwIs the stator winding heat capacity.
8. The method for monitoring the temperature of the permanent magnet motor rotor in real time according to claim 1, wherein when the permanent magnet motor is a surface-mounted permanent magnet synchronous motor, the target motor equivalent thermal network model comprises: rotor core node (r), permanent magnet node (m), stator core node(s), stator winding node (w), motor surrounding environment node (a), cooling medium node (C), rotor core heat capacity (C)r) Permanent magnet heat capacity (C)m) Stator core heat capacity (C)s) Stator winding heat capacity (C)w) Rotor core loss (P)r) Permanent magnet loss (P)m) Stator core loss (P)s) Stator winding loss (P)w) First thermal resistance (R)a,r) Second thermal resistance (R)r,m) Third thermal resistance (R)m,s) Fourth thermal resistance (R)s,w) Fifth thermal resistance (R)a,w) Sixth thermal resistance (R)c,s) Wherein, in the step (A),
the rotor core node (R) and the motor surrounding environment node (a) are connected through the first thermal resistance (R)a,r) Connected, the rotor core node (R) and the permanent magnet node (m) pass through the second thermal resistance (R)r,m) Connected, the permanent magnet node (m) and the stator core node(s) passing through the third thermal resistance (R)m,s) Connected, the stator core node(s) and the stator winding node (w) are connected through the fourth thermal resistance (R)s,w) Connected, the stator winding node (w) and the motor surrounding node (a) are connected through a fifth thermal resistance (R)a,w) Connected, the stator core node(s) and the cooling medium node (c) passing through the sixth thermal resistance (R)c,s) Connecting;
the rotor core heat capacity (C)r) Representing the heat absorption or dissipation capacity of the rotor core node (r), the rotor core loss (P)r) A heat source representing a node (r) of the rotor core, the permanent magnet heat capacity (C)m) Representing the heat absorption or dissipation capacity of the permanent magnet node (m), the permanent magnet losses (P)m) A heat source representing the permanent magnet node (m), the stator core heat capacity (C)s) Representing the heat absorption or dissipation capacity of the stator core node(s), the stator core lossConsumption (P)s) A heat source representing a node(s) of the stator core, the stator winding heat capacity (C)w) Representing the heat absorption or dissipation capacity of the stator winding nodes (w), the stator winding losses (P)w) Represents a heat source of the stator winding node (w).
9. The method for monitoring the temperature of the permanent magnet motor rotor according to claim 8, wherein when the permanent magnet motor is a surface-mounted permanent magnet synchronous motor, the spatial state matrix is:
y(t)＝CT(t)+DP(t)
since the temperature of the motor ambient node (a) and the temperature of the cooling medium node (c) change to 0 over time, then:
D＝0
wherein the content of the first and second substances,
is the temperature rise rate at a node i, T (t) is a state vector formed by the working temperature of any node in the target motor equivalent heat network model, P (t) is an input vector formed by the heat source loss of any node in the target motor equivalent heat network model, y (t) is an output vector formed by the working temperature of any node in the target motor equivalent heat network model, A is a system matrix, B is an input matrix, C is an output matrix, D is a feedforward matrix, a is a node of the surrounding environment of the motor, C is a cooling medium node, R is a rotor core node, m is a permanent magnet node, s is a stator core node, w is a stator winding node, R (t) is a stator core nodea,rIs a first thermal resistance, Rr,mIs the second thermal resistance, Rm,sIs a third thermal resistance, Rs,wIs a fourth thermal resistance, Ra,wIs a fifth thermal resistance, Rc,sIs a sixth thermal resistance, CrFor heat capacity of rotor core, CmIs the heat capacity of a permanent magnet, CsFor stator core heat capacity, CwIs the stator winding heat capacity.
10. A real-time monitoring model of permanent magnet temperature of a permanent magnet motor rotor is characterized by comprising the following components:
the node acquisition module is used for carrying out discretization processing on the motor according to the structure of the permanent magnet motor to obtain a plurality of nodes;
the node circuitization module is used for expressing the heat transfer between the adjacent nodes by thermal resistance to obtain a plurality of thermal resistances;
the model establishing module is used for connecting a plurality of nodes into a heat network model by using a plurality of thermal resistances according to a heat transfer path of the permanent magnet motor, and simplifying the connected heat network model to obtain a target motor equivalent heat network model, wherein in the target motor equivalent heat network model, the heat absorption or heat dissipation capacity of each node is expressed by heat capacity, and the heat source of each node is expressed by loss;
and the temperature acquisition module is used for calculating a space state matrix of each node in the target motor equivalent heat network model, calculating the working temperature of the permanent magnet and the working temperature of the stator winding by combining a loss-temperature bidirectional coupling algorithm, and outputting the working temperature of the permanent magnet.
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