A method for estimating temperature of a rotor of a six-phase electric machine

Abstract

The application discloses a six-phase motor rotor temperature estimation method and belongs to the technical field of motor rotor temperature estimation. dq The specific estimation method comprises the following steps: modeling based on stator temperature, shaft inductance and calculating the value of inductance; constructing a torque equation: wherein T is a torque value, K is a reluctance torque coefficient, K is an electromagnetic torque coefficient, p is a motor pole pair number, and Ψ is a motor rotor flux; calculating the motor rotor flux value through the torque equation; constructing a rotor temperature segmented function for the motor rotor flux value; and calculating the rotor temperature value. T T The application calculates the rotor temperature value by constructing a torque equation based on inductance parameters, thereby avoiding the cost of using hardware measurement facilities and achieving high precision. Compared with a table-based estimation method, the method does not need to obtain a table in advance, is simple and easy to implement, and is suitable for the calculation of rotor temperature of most six-phase permanent magnet synchronous motors.​

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of motor rotor temperature estimation, more specifically to a six-phase motor rotor temperature estimation method. BACKGROUND

[0002] At present, the rotor temperature of a six-phase motor for vehicle cannot be directly calculated, and in most cases, the rotor temperature is obtained depending on calibration. However, the calibration of the rotor temperature not only highly depends on the test environment, but also has high requirements for the precision of the test equipment and the differences between individual motors. Therefore, in many cases, the data is distorted to some extent and the calibration operation is complex.

[0003] A permanent magnet synchronous motor rotor temperature estimation method, device, motor and vehicle are disclosed in Chinese patent application publication No. CN 116780960A, which establishes a flux linkage observer of a continuous model based on a voltage equation in a d-q coordinate system, introduces the difference between the estimated current and the actual current as feedback, establishes the corresponding relationship between the rotor temperature and the flux linkage, estimates the real-time rotor temperature according to the value of the flux linkage observer, and performs temperature post-processing according to the motor working condition. The estimated current of the patent is obtained by looking up the table according to the estimated flux linkage value. On the one hand, the estimated flux linkage value has a certain error, and on the other hand, the table of flux linkage needs to be obtained by pre-test, which is relatively cumbersome. In addition, the current difference itself has an error, and the flux linkage difference of the d-q axis obtained after the current difference passes through the integrator will have a cumulative error.

[0004] Chinese patent application publication No. CN 114928289A discloses a permanent magnet synchronous motor rotor temperature estimation method, which includes the following steps: S1, obtaining motor basic parameters; recording the u s_LPF of the motor under different temperatures, different torques and different speeds by a temperature sensor, and formulating a MAP; u s_LPF is the value of the u s after low-pass filtering, u s is the d-p axis voltage module value of the motor; S2, the MCU looks up the table according to the instruction of the VCU to obtain the d-axis current i d and the q-axis current i q of the motor; S3, the u d , u q of the current motor are obtained according to i d and i s , and the u s is low-pass filtered to obtain the u s_LPF of the current motor; S4, the rotor temperature of the motor is obtained by looking up the table according to the u s_LPF and the MAP obtained in S1 according to a certain rule. In the estimation process of the patent, two lookups are applied, and the table needs to be obtained by pre-test, which is relatively cumbersome. Summary of the Invention

[0005] This invention provides a method for estimating the rotor temperature of a six-phase motor, aiming to solve the problems of the existing method of estimating the rotor temperature of a permanent magnet synchronous motor by looking up tables, which requires prior testing and is relatively cumbersome.

[0006] The present invention adopts the following technical solution:

[0007] A method for estimating the rotor temperature of a six-phase motor includes the following steps:

[0008] Step 1: Based on stator temperature dq Shaft inductor and Modeling is performed, and the inductance is calculated. and The value;

[0009] Step 2: Construct the torque equation: ,in, This is the torque value. The reluctance torque coefficient is... The electromagnetic torque coefficient, This represents the number of pole pairs of the motor. For motor rotor flux linkage;

[0010] Step 3: Calculate the rotor flux linkage of the motor using the torque equation. value;

[0011] Step 4: Adjust the rotor flux linkage of the motor. Value of rotor temperature T The piecewise function is used to calculate the rotor temperature value. T .

[0012] In a preferred embodiment, in step one above dq Shaft inductor and The following formula is used for modeling:

[0013]

[0014]

[0015] in, , These represent the stator temperatures. Stator temperature Lower winding corresponding inductance Shaft inductance value, and , These represent the stator temperatures. Stator temperature Lower winding corresponding inductance Shaft inductance value Indicate the temperature coefficient of inductance.

[0016] In a preferred embodiment, the above step two is , Respectively, the following formula is used to calculate: , ; wherein, is the number of motor pole pairs, is Shaft current, is Shaft current.

[0017] In a preferred embodiment, the specific method of the above step four is as follows: ① The motor rotor flux is segmented, which is divided into four segments, namely flux A segment, flux B segment, flux C segment and flux D segment, and the corresponding flux threshold values of each segment are , , , , the corresponding rotor temperature values of each segment are , , and , and the corresponding coefficients of each segment are , , and ; ② The relationship between each segment flux and its rotor temperature is clear, which is: and ; ③ The rotor temperature T and the segmented function of the motor rotor flux are as follows: .

[0018] In a preferred embodiment, the above flux threshold , , , is the known parameter of the motor, which can be modified according to different motors.

[0019] In a preferred embodiment, the above is 25℃, is 90℃, is 135℃, is 165℃.

[0020] From the above description of the present application, compared with the prior art, the present application has the following advantages:

[0021] The application is based on inductance parameters and a torque equation to calculate the estimated rotor temperature value, avoids the cost of using hardware measurement facilities, and has high precision. Compared with the estimation method based on table lookup, the method does not need to obtain the table in advance by testing, is simple and easy to implement, is suitable for the calculation of rotor temperature of most six-phase permanent magnet synchronous motors, and provides effective guarantee for temperature fault protection and early maintenance of related parts. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The flowchart of the embodiment of the application is shown. DETAILED DESCRIPTION

[0023] The specific embodiments of the application will be described below with reference to the accompanying drawings. In order to fully understand the application, many details are described below, but the application can be implemented without these details for those skilled in the art. For well-known components, methods and processes, the following will not be described in detail.

[0024] A six-phase motor rotor temperature estimation method, with reference to Figure 1 , comprising the following steps:

[0025] Step 1: Model based on stator temperature dq axial inductance and , and calculate the values of inductance and .

[0026] dq axial inductance and are modeled by the following formula:

[0027]

[0028]

[0029] wherein, , respectively represent the stator temperature , the stator temperature corresponding inductance axial inductance value, and , respectively represent the stator temperature , the stator temperature corresponding inductance axial inductance value; represents the temperature coefficient of inductance, which can be specifically taken as 3.0×10 -6 / ℃.

[0030] The stator temperature , the stator temperature The inductance can be directly measured or calculated by the above modeling formula and .

[0031] Step two: construct the torque equation.

[0032] The torque equation is as follows: Wherein, is the torque value, is the reluctance torque coefficient, is the electromagnetic torque coefficient, is the motor pole pair number, is the motor rotor flux.

[0033] , are calculated by the following formula respectively: , ; wherein, is the motor pole pair number; is the axial current, is the axial current, , read the corresponding ammeter when the torque is applied.

[0034] Step three: calculate the motor rotor flux value by the torque equation.

[0035] The motor rotor flux expression is: .

[0036] Step four: construct the rotor temperature piecewise function for the motor rotor flux T value, and calculate the rotor temperature value T .

[0037] Since the flux will change with temperature, the rotor temperature is indirectly obtained by the rotor flux , and the specific steps are as follows:

[0038] ① In order to obtain the rotor temperature value more accurately, the motor rotor flux needs to be segmented into four segments, namely the flux A segment, the flux B segment, the flux C segment and the flux D segment, and the corresponding flux threshold values of each segment are , , , , and the corresponding rotor temperature values of each segment are , , and , the coefficients corresponding to each segment of magnetic chain are , , and .

[0039] 2. The relationship between each segment of magnetic chain and its rotor temperature is clear, which is: and .

[0040] Magnetic chain threshold , , , is a known parameter of the motor, which is modified according to different motors; and is 25℃, is 90℃, is 135℃, is 165℃.

[0041] 3. According to the rotor magnetic chain value calculated in the above step three, the temperature value T is obtained by using the following method:

[0042] (a) If is satisfied, the rotor temperature ;

[0043] (b) If is satisfied, the rotor temperature ;

[0044] (c) If is satisfied, the rotor temperature ;

[0045] (d) If is satisfied, the rotor temperature .

[0046] That is, the rotor temperature T and the segmented function of the motor rotor magnetic chain are as follows:

[0047] .

[0048] The above is only a specific embodiment of the present application, but the design concept of the present application is not limited thereto, and any non-essential modification of the present application using this concept shall be deemed as an act of infringing the protection scope of the present application.

Claims

1. A method for estimating the rotor temperature of a six-phase motor, characterized in that, Includes the following steps: Step 1: Based on stator temperature dq Shaft inductor and Modeling is performed, and the inductance is calculated. and The value; Step 2: Construct the torque equation: ,in, This is the torque value. The reluctance torque coefficient is... The electromagnetic torque coefficient is... For motor rotor flux linkage; Step 3: Calculate the rotor flux linkage of the motor using the torque equation. value; Step 4: Adjust the rotor flux linkage of the motor. Value of rotor temperature T The piecewise function is used to calculate the rotor temperature. T The specific method is as follows: ① Divide the motor rotor flux linkage into four segments: flux linkage segment A, flux linkage segment B, flux linkage segment C, and flux linkage segment D. The flux linkage thresholds corresponding to each segment are as follows: , , , The rotor temperature values ​​corresponding to each segment of the magnetic flux are as follows: , , and The coefficients corresponding to each segment of the magnetic flux linkage are as follows: , , and ; ② Clarify the relationship between each segment of the magnetic flux and its rotor temperature, namely: and ③ Rotor temperature T With motor rotor magnetic flux The piecewise function is as follows: .

2. The method for estimating the rotor temperature of a six-phase motor as described in claim 1, characterized in that: In step one dq Shaft inductor and The following formula is used for modeling: in, , These represent the stator temperatures. Stator temperature Lower winding corresponding inductance Shaft inductance value, and , These represent the stator temperatures. Stator temperature Lower winding corresponding inductance Shaft inductance value, This represents the temperature coefficient of inductance.

3. The method for estimating the rotor temperature of a six-phase motor as described in claim 1, characterized in that: In step two , The following formulas were used to calculate the results: , ;in, This represents the number of pole pairs of the motor. for shaft current, for Axis current.

4. The method for estimating the rotor temperature of a six-phase motor as described in claim 1, characterized in that: The magnetic flux threshold , , , These are the known parameters of the motor, which are modified according to different motors.

5. The method for estimating the rotor temperature of a six-phase motor as described in claim 1, characterized in that: The It is 25℃. It is 90℃. It is 135℃. The temperature is 165℃.

Images