Multi-loss measuring device and method based on equivalent real motor rotor magnetic field

Abstract

The invention discloses a multi-loss measurement device and method based on an equivalent real motor rotor magnetic field, and relates to the technical field of motor measurement. The invention aims to solve the problem that the specific value of each loss cannot be accurately obtained when the motor performance is analyzed and the design is optimized in the prior art. The method comprises the following steps: preparing a rectangular stator iron core with the same polar distance or pitch as a tested motor, and arranging excitation iron cores at groove openings of grooves at two ends; applying current to the stator winding, acquiring terminal voltage and calculating resistance of the stator winding; applying current to the magnet exciting coil to form a leakage magnetic field, collecting the magnetic field intensity of each strand of the stator winding, constructing an associated equation of the current magnetic field, and further calculating strand current, circulation and total circulation loss in sequence. And calculating the basic copper loss by taking the average effective value of strand current in the stator winding. And calculating the total power loss through a pre-established model. And calculating stator iron loss according to an empirical formula. And obtaining the eddy current loss based on the stator iron loss, the total circulation loss, the basic copper loss and the total power loss.

Description

Technical Field

[0001] The invention belongs to the technical field of motor measurement. Background Art

[0002] During the operation of the motor system, it is extremely important to accurately measure various losses. Losses are not only directly related to the efficiency and performance of the motor, but also affect its reliability and service life. Understanding the losses of the motor can help engineers optimize the motor design, improve energy efficiency, and reduce operating costs. For example, in industrial production, the motor is the main power source, and its efficiency improvement means a lot of energy savings; in the field of electric vehicles, the reduction of motor losses helps to extend the driving range. Accurately and conveniently measuring losses is an important issue that needs to be solved in the field of motors.

[0003] In order to reduce AC losses, the industry currently generally adopts the method of dividing the winding into strands. By increasing the surface area of ​​the conductor, the problem of increased AC resistance caused by the skin effect is effectively reduced, thereby reducing AC losses. However, this method will cause circulating currents between the windings, resulting in circulating current losses. DC copper loss, circulating current loss, and eddy current loss are intertwined and jointly affect the operation of the motor. Due to the complexity of the actual motor structure and operating principle, the mechanisms of different losses are interrelated, and it is difficult to distinguish them one by one through conventional measurement methods. This makes it impossible to accurately obtain the specific values ​​of each loss when analyzing motor performance and optimizing design, and it is difficult to take targeted improvement measures. This situation has greatly limited the further improvement of motor performance and hindered the research and development of high-efficiency motors. Summary of the invention

[0004] The present invention aims to solve the problem in the prior art that it is impossible to accurately obtain the specific value of each loss when analyzing motor performance and optimizing design. A multi-loss measurement device and method based on an equivalent real motor rotor magnetic field are provided.

[0005] The multi-loss measurement device based on the equivalent real motor rotor magnetic field comprises: a rectangular stator core 10, two excitation cores 12, a collection unit, a host computer 17 and two excitation units;

[0006] The rectangular stator core 10 has the same pitch as the motor under test, a plurality of grooves are evenly opened on the surface of the rectangular stator core 10, and stator windings 11 are wound in the grooves at both ends, and the two excitation cores 12 are both U-shaped, and the two excitation cores 12 are respectively arranged at the notches of the grooves at both ends, and an air gap is left between the excitation core 12 and the rectangular stator core 10, and an excitation coil 13 is wound on each excitation core 12;

[0007] The two excitation units are used to apply current to the stator winding 11 and the excitation coil 13 respectively;

[0008] The acquisition unit is used to acquire the magnetic field intensity of each strand of the stator winding 11 and send it to the host computer 17;

[0009] The host computer 17 is used to construct a correlation equation between the magnetic field intensity of each strand and the strand current to obtain the current of each strand, and then calculate the total power loss, basic copper loss, total circulating current loss and eddy current loss of the stator winding 11 based on the current of each strand.

[0010] Further, the above acquisition unit includes: a magnetic field collector 14, a signal amplification circuit 15 and a signal conversion module 16. The magnetic field collector 14 includes a plurality of micro Hall sensors, and a micro Hall sensor is provided at each end of each strand of the stator winding 11;

[0011] The micro Hall sensor is used to acquire the magnetic field intensity of the strand where it is located, and send the magnetic field intensity to the signal conversion module 16 after being amplified by the signal amplification circuit 15. The signal conversion module 16 performs analog-to-digital conversion on the amplified magnetic field intensity signal and then sends it to the host computer 17.

[0012] Further, the above excitation unit includes a single-phase step-down transformer 18 and an adjustable AC power supply 19;

[0013] In the excitation unit connected to the stator winding 11, its adjustable AC power supply 19 applies a known stable DC current to the stator winding 11 through the single-phase step-down transformer 18, acquires the voltage at both ends of the stator winding 11, and then calculates the resistance value of the stator winding 11;

[0014] In the excitation unit connected to the excitation coil 13, its adjustable AC power supply 19 applies a current to the excitation coil 13 through the single-phase step-down transformer 18 to make the excitation iron core 12 form a leakage magnetic field.

[0015] Further, the above host computer 17 is used to construct a correlation equation between the magnetic field intensity of each strand and the strand current to obtain the current of each strand, and then calculate the total power loss, basic copper loss, total circulating current loss and eddy current loss of the stator winding 11 based on the current of each strand, including:

[0016] Construct a correlation equation between the current and magnetic field of each strand in the stator winding 11, and then calculate the current of each strand in the stator winding 11. Calculate the circulating current of each strand according to the currents of each strand, and calculate the circulating current loss of each strand according to the circulating currents of each strand;

[0017] Take the average effective value of the strand current in the stator winding 11, and calculate the basic copper loss of the stator winding 11 according to the average effective value of the strand current;

[0018] Under the action of the leakage magnetic field, the voltage and current at both ends of the stator winding 11 are collected, and the total power loss of the stator winding 11 is calculated through a pre-established model;

[0019] The stator iron loss is calculated according to the empirical formula;

[0020] The eddy current loss is obtained based on the stator iron loss, the circulating current loss, the basic copper loss, and the total power loss.

[0021] Furthermore, the expression of the correlation equation between the current of each strand in the stator winding 11 and the magnetic field is as follows:

[0022]

[0023] Among them, the total number of strands in the stator winding 11 is 2n, I 2n is the current of the 2nth strand in the stator winding 11, B 2n is the magnetic field strength collected by the 2nth micro Hall sensor, and k (2n,2n) is the proportionality coefficient between the magnetic field strength collected by the 2nth micro Hall sensor and the current of the 2nth strand;

[0024] The circulating current of each strand is calculated according to the current of each strand, and the expression is as follows:

[0025] I ck = I k - I av ,

[0026] Among them, I ck is the circulating current of the kth strand, I k is the current of the kth strand, k = 1, 2,..., 2n, and I av is the average effective value of the strand current;

[0027] The circulating current loss of each strand is calculated according to the circulating current of each strand, and the expression is as follows:

[0028]

[0029] Among them, P ck is the circulating current loss of the kth strand, and R dc is the resistance value of the stator winding 11;

[0030] The sum of the circulating current losses of all strands is obtained as the total circulating current loss P c .

[0031] Furthermore, the basic copper loss of the stator winding 11 is calculated according to the average effective value of the strand current, and the expression is as follows:

[0032]

[0033] Among them, P dc is the basic copper loss of the stator winding 11, I av is the average effective value of the strand current, and R dc is the resistance value of the stator winding 11.

[0034] Furthermore, the eddy current loss is obtained based on the stator iron loss, circulating current loss, basic copper loss, and total power loss, and the expression is as follows:

[0035] P eddy = P - P dc - P c - P Fe ,

[0036] Among them, P eddy is the eddy current loss, P is the total power loss, P dc is the basic copper loss, P c is the total circulating current loss, and P Fe is the stator iron loss.

[0037] The multi-loss measurement method based on the equivalent real motor rotor magnetic field includes:

[0038] Prepare a rectangular stator core 10 with the same pole pitch or pitch as the motor under test. A plurality of grooves are evenly opened on the surface of the rectangular stator core 10. The stator winding 11 is wound in the grooves at both ends, and a U-shaped excitation core 12 is respectively arranged at the notch of the grooves at both ends. There is an air gap between the excitation core 12 and the rectangular stator core 10, and an excitation coil 13 is wound on each excitation core 12;

[0039] Apply a known stable DC current to the stator winding 11, collect the voltage at both ends of the stator winding 11, and then calculate to obtain the resistance value of the stator winding 11;

[0040] Apply a current to the excitation coil 13 to make the excitation core 12 form a leakage magnetic field. Under the action of this leakage magnetic field, collect the magnetic field intensity of each strand of the stator winding 11, construct the correlation equation between the current and the magnetic field of each strand in the stator winding 11, and then calculate the current of each strand in the stator winding 11. Calculate the circulating current of each strand according to the currents of each strand, calculate the total circulating current loss of the stator winding 11 according to the circulating currents of each strand, take the average effective value of the strand current in the stator winding 11, and calculate the basic copper loss of the stator winding 11 according to the average effective value of the strand current. Collect the voltage and current at both ends of the stator winding 11, calculate the total power loss of the stator winding 11 through a pre-established model, calculate the stator iron loss according to the empirical formula, and obtain the eddy current loss based on the stator iron loss, total circulating current loss, basic copper loss, and total power loss.

[0041] Further, the expression of the correlation equation between the current of each strand in the stator winding 11 and the magnetic field is as follows:

[0042]

[0043] Among them, the total number of strands in the stator winding 11 is 2n, I 2n is the current of the 2nth strand in the stator winding 11, B 2n is the magnetic field strength collected by the 2nth micro Hall sensor, and k (2n,2n) is the proportionality coefficient between the magnetic field strength collected by the 2nth micro Hall sensor and the current of the 2nth strand;

[0044] The expression for calculating the circulating current of each strand according to the current of each strand is as follows:

[0045] I ck = I k - I av ,

[0046] Among them, I ck is the circulating current of the kth strand, I k is the current of the kth strand, k = 1, 2,..., 2n, and I av is the average effective value of the strand current;

[0047] The expression for calculating the circulating current loss of each strand according to the circulating current of each strand is as follows:

[0048]

[0049] Among them, P ck is the circulating current loss of the kth strand, and R dc is the resistance value of the stator winding 11;

[0050] Summing up the circulating current losses of all strands to obtain the total circulating current loss P c .

[0051] Further, the expression for calculating the basic copper loss of the stator winding 11 according to the average effective value of the strand current is as follows:

[0052]

[0053] Among them, P dc is the basic copper loss.

[0054] The expression for obtaining the eddy current loss based on the stator iron loss, total circulating current loss, basic copper loss, and total power loss is as follows:

[0055] P eddy = P - P dc - P c - PFe ,

[0056] Among them, P eddy is the eddy current loss, P is the total power loss, P Fe is the stator iron loss.

[0057] The beneficial effects of the present invention are as follows:

[0058] 1. The present invention realizes accurate measurement of AC loss of motor winding in local area by adopting rectangular structure and multiple groove designs. Silicon steel sheets are processed into rectangular structure by using a pitch area in the original stator core, without major adjustment of the entire motor, which not only ensures the representativeness of the detection area, but also reduces the cost of transformation and implementation difficulty. The processing of rectangular core makes the detection area have a standardized and regular geometric structure, which is convenient for the implementation of subsequent process flow and the establishment of data model, and provides a reliable basis for accurately simulating the internal magnetic field distribution of the whole machine.

[0059] 2. A U-shaped excitation core is arranged at the winding slot to be equivalent to the effect of the real motor rotor magnetic field, and an air gap is reserved between the stator core and the excitation core. The formation of a controllable leakage magnetic field is achieved by aligning one side of the U-shaped core with the slot at a predetermined position. By adjusting the parameters of the excitation coil, the intensity of the leakage magnetic field can be adjusted, providing a precise excitation environment for subsequent loss measurements. This leakage magnetic field control design enables local magnetic field changes to be equivalent to reflecting the AC loss in the actual winding, and reduces the measurement error caused by magnetic field instability.

[0060] 3. Use a micro Hall sensor to detect the leakage magnetic field in the slot in real time. The micro Hall sensor has the characteristics of small size, high sensitivity, and fast response speed. It can capture tiny magnetic field changes and convert them into voltage signals for subsequent data collection. The detected leakage magnetic field information and the voltage and current signals at both ends of the winding together constitute a multi-dimensional data system. By establishing a mathematical model or calibration curve, the eddy current loss of the local winding can be calculated. The multi-data collection and analysis method effectively improves the measurement accuracy and reduces the impact of environmental and interference factors on the results.

[0061] 4. The present invention has a high level of integration and automation. Since the detection device has a simple structure and modular design, it is easy to integrate with other systems. Through automated data acquisition and processing, it can not only quickly feedback the AC loss of the motor winding, but also provide data support for subsequent motor performance optimization. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 This is the principle block diagram of the multi-loss measurement device based on the equivalent real motor rotor magnetic field;

[0063] Figure 2Schematic diagram of the end structure when the rectangular stator core and the excitation core cooperate with each other;

[0064] Figure 3 Schematic diagram of a single-slot winding without insulated strands;

[0065] Among them, there are a rectangular stator core 10, a stator winding 11, an excitation core 12, an excitation coil 13, a magnetic field collector 14, a signal amplification circuit 15, a signal conversion module 16, a host computer 17, a single-phase step-down transformer 18, and an AC adjustable power supply 19. Specific implementation mode

[0066] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0067] In previous research and technologies, it has always been a major difficulty to achieve the effect of an equivalent real rotor magnetic field. For an equivalent real rotor magnetic field, it is necessary to accurately simulate the distribution, intensity, and change characteristics of the rotor magnetic field during motor operation, which poses high requirements for the design of the device. To achieve an equivalent real rotor magnetic field, not only is it necessary to accurately simulate its physical structure in device design, but also to achieve consistency in electromagnetic characteristic simulation. Previous technologies cannot comprehensively and accurately simulate the behavior of the real rotor magnetic field under various working conditions. This implementation mode proposes a multi-loss measurement device and a test method based on an equivalent real motor rotor magnetic field, which has overcome the problems existing in the prior art and can achieve the effect of an equivalent real rotor magnetic field. On this basis, accurate measurement of three important losses, namely DC copper loss, circulating current loss, and eddy current loss, can be realized. It brings a new solution to the field of motor loss measurement and makes new progress in promoting motor performance research and optimized design.

[0068] Specific implementation mode one: Refer to Figures 1 to 3 Specifically illustrate this implementation mode. The multi-loss measurement device based on an equivalent real motor rotor magnetic field described in this implementation mode includes: a rectangular stator core 10, two excitation cores 12, a magnetic field collector 14, a signal amplification circuit 15, a signal conversion module 16, a host computer 17, a single-phase step-down transformer 18, and an adjustable AC power supply 19.

[0069] According to the pitch of the motor under test, a local area with the same pitch as the motor under test is selected from the stator core of the motor under test. The silicon steel sheet is processed into a rectangular structure according to the size of the local area, which is used as the rectangular stator core 10. This rectangular structure not only facilitates the subsequent winding of the winding, but also ensures the overall rigidity and magnetic circuit performance of the core. A plurality of grooves are uniformly formed on the surface of the rectangular stator core 10. The sizes and spacings of the grooves are determined according to the parameters of the motor under test and the characteristics of the magnetic field distribution, so as to ensure that the local area can truly simulate the internal magnetic circuit of the whole machine and ensure the matching of the subsequent winding and the excitation structure. The local processing method adopted in this embodiment not only avoids the high cost of the whole machine transformation, but also can accurately reproduce the magnetic field characteristics of the stator core in the local area, which is convenient for the calibration and analysis of the subsequent measurement data.

[0070] Among all the grooves of the rectangular stator core 10, two grooves located at both ends are selected for winding the stator winding 11. The stator winding 11 adopts a multi-layer coil structure, and the coils of each layer are continuously arranged in the radial direction, extending from the slot opening to the slot bottom, and the turns are evenly arranged after winding. Ensure that each layer of winding is in the same magnetic field region to truly reflect the magnetic field distribution inside the motor. The number of turns and the arrangement spacing of each layer of coil should be controlled to ensure the symmetry and uniformity of the magnetic field distribution. The winding structure of continuous and uniform arrangement adopted in this embodiment can effectively reduce the local magnetic field abnormality caused by uneven winding, accurately capture the change of the leakage magnetic field, and at the same time reduce the additional loss caused by the cross-over and superposition of the coils.

[0071] At the slot openings of the grooves where the stator winding 11 is wound, a U-shaped excitation core 12 is respectively arranged. An excitation coil 13 is wound on the excitation core 12 to simulate the effect of the magnetic field of the real motor rotor. An air gap is left between the rectangular stator core 10 and the excitation core 12 to maintain magnetic field coupling. This air gap is not only an important parameter for controlling the leakage magnetic field, but also a necessary measure to ensure the excitation effect. When designing the excitation core 12, its magnetic coupling with the stator core should be considered. By adjusting the current of the excitation coil 13 and the size of the air gap, a controllable leakage magnetic field that meets the requirements is formed. A part of the excitation core 12 is aligned with the stator slot opening, which is used to concentrate and convey the excitation magnetic flux into the stator slot to form the required leakage magnetic field; the other part serves as a magnetic flux return path to adjust and stabilize the entire magnetic circuit. The excitation core 12 is made of high-permeability silicon steel sheet, and an insulating paint is coated on the surface of the core or surface treatment is carried out to prevent short circuit and electromagnetic interference. In this embodiment, the air gap and the excitation core 12 make the excitation magnetic field locally concentrated, forming an obvious leakage magnetic field at the slot opening, which is beneficial to the detection by the Hall sensor. Winding the excitation coil 13 on the excitation core 12 can accurately simulate the effect of the rotor magnetic field; at the same time, the controllability of the excitation magnetic field provides an adjustment basis for the loss test under different working conditions in the future.

[0072] The exciting iron core 12 forms the required leakage magnetic field. The magnetic field collector 14 (micro Hall sensor) is placed in the leakage magnetic field area where the stator winding slot opening is located, and is used to detect the intensity and distribution of the leakage magnetic field in the slot under the action of excitation. Since the slot opening is most affected by the leakage magnetic field, the micro Hall sensor is installed in the groove near the slot opening, which can convert the leakage magnetic field signal into a voltage output and transmit it to the data acquisition module after amplification. According to the need, the excitation current is adjusted to change the magnetic field magnitude until the leakage magnetic field that meets the rotor magnetic field strength is achieved, so as to simulate the complex magnetic field environment where the motor winding is located. In this embodiment, the micro Hall sensor has a small size and high sensitivity, and has the characteristics of fast response speed and high precision. It can accurately capture the change of the leakage magnetic field, transmit the detected magnetic field signal to the data acquisition system through a preamplifier, provide an accurate basis for the subsequent electrical parameter analysis, and make the mathematical model established through the magnetic field - electrical parameter correspondence relationship have higher measurement accuracy. The installation of the sensor should avoid measurement data fluctuations caused by vibration or external interference, and anti-vibration materials or fixed brackets can be used.

[0073] The single-phase step-down transformer 18 and the adjustable AC power supply 19 constitute an excitation unit. In the excitation unit connected to the stator winding 11, the single-phase step-down transformer 18 and the adjustable AC power supply 19 are respectively connected to both ends of the stator winding 11, apply a known stable DC current to the stator winding 11, and record the voltage drop at both ends of the stator winding 11, then the DC resistance of the stator winding 11 can be measured; to reduce accidental errors, multiple measurements are taken and averaged to obtain the resistance value R of the stator winding 11. dc In the excitation unit connected to the exciting coil 13, its adjustable AC power supply 19 applies a current to the exciting coil 13 through the single-phase step-down transformer 18 to make the exciting iron core 12 form a leakage magnetic field.

[0074] Install the magnetic field collector 14 (micro Hall sensor) at the end of the stator winding 11 and record the position where the Hall element is located. The voltage U output by the Hall element H successively passes through the signal amplification circuit 15 and the signal conversion module 16 to the upper computer 17. In the upper computer 17, calculate the magnetic field strength B at the position where the Hall element is located:

[0075]

[0076] where k H is the sensitivity coefficient of the Hall element.

[0077] Construct the correlation equation between the current of the stator winding 11 at different positions at the end and the magnetic field, and calculate the current of each strand in the stator winding 11:

[0078]

[0079] where, I1~I 2nare the currents of the 1st to 2nth strands in the stator winding 11; B1 to B 2n are the magnetic field intensities measured by the 1st to 2nth Hall elements at the ends of the stator winding strands; k (1,1) ~k (2n,2n) are the proportionality coefficients of the magnetic field intensities measured by the 1st to 2nth Hall elements to the strand currents of the 1st to 2nth strands respectively.

[0080] The circulating current of a single strand is:

[0081] I ck = I k - I av ,

[0082] where, I ck is the circulating current of the kth strand, I k is the current of the kth strand, k = 1, 2,..., 2n, and I av is the average effective value of the strand current.

[0083] After obtaining the circulating current of a single strand, according to the circulating current loss P ck of the kth strand can be obtained.

[0084] Summing up the circulating current losses of all strands to get the total circulating current loss P c .

[0085] Connect the current lead and voltage measurement lead to two test endpoints of the stator winding 11 respectively. To reduce accidental errors, take the average effective value I av of the strand current. According to to obtain the basic copper loss P dc of the stator winding 11.

[0086] Under the action of the leakage magnetic field, voltage and current changes will occur at both ends of the stator winding 11. Connect high-precision voltage and current sensors, voltmeters or ammeters to both ends of the stator winding 11 respectively, and collect voltage and current data in real time to provide data for loss calculation. The data is uploaded to the host computer 17, and through a pre-established mathematical model or calibration curve, the total power loss P of the stator winding 11 is calculated.

[0087] The stator iron loss P Fe can be obtained according to the empirical formula.

[0088] From P eddy = P - P dc - P c - P Fe the eddy current loss P eddy of the stator winding 11 can be calculated.

[0089] In this embodiment, the multi-parameter joint acquisition and analysis method can effectively eliminate the interference of environmental factors and systematic errors on loss calculation, and improve the stability and accuracy of measurement results.

[0090] The finite element simulation calculation and comparison are carried out on the overall loss of the measured motor and the loss of the test device. The simulation calculation results under the rated load are shown in Table 1. Compared with the finite element simulation results of the original sample machine by using the multi-loss measurement device and test method based on the equivalent real motor rotor magnetic field, the total loss error can be guaranteed to be about 3%.

[0091] Table 1 Loss comparison table under rated load

[0092]

[0093]

[0094] Specific embodiment two: The multi-loss measurement method based on the equivalent real motor rotor magnetic field described in this embodiment includes:

[0095] Prepare a rectangular stator core 10 with the same pole pitch or coil pitch as the measured motor. A plurality of grooves are evenly opened on the surface of the rectangular stator core 10. Stator windings 11 are wound in the grooves at both ends, and a U-shaped excitation core 12 is respectively arranged at the groove openings at both ends. There is an air gap between the excitation core 12 and the rectangular stator core 10, and excitation coils 13 are wound on each excitation core 12.

[0096] Apply a known stable DC current to the stator winding 11, collect the voltage at both ends of the stator winding 11, and then calculate the resistance value R of the stator winding 11 dc .

[0097] Apply a current to the excitation coil 13 to make the excitation core 12 form a leakage magnetic field. Under the action of this leakage magnetic field, collect the magnetic field intensity of each strand of the stator winding 11, construct the correlation equation between the current and the magnetic field of each strand in the stator winding 11, and calculate the current of each strand in the stator winding 11:

[0098] The expression of the correlation equation between the current and the magnetic field of each strand in the stator winding 11 is as follows:

[0099]

[0100] Among them, the total number of strands in the stator winding 11 is 2n, I 2n is the current of the 2nth strand in the stator winding 11, B 2n is the magnetic field intensity collected by the 2nth micro Hall sensor, and k (2n,2n) is the proportionality coefficient between the magnetic field intensity collected by the 2nth micro Hall sensor and the current of the 2nth strand.

[0101] Calculate the circulating current of each strand of wire according to the current of each strand:

[0102] I ck = I k - I av ,

[0103] where I ck is the circulating current of the k-th strand of wire, I k is the current of the k-th strand of wire, k = 1, 2,..., 2n, and I av is the average effective value of the strand current.

[0104] Calculate the circulating current loss of each strand of wire according to the circulating current of each strand. The expression is as follows:

[0105]

[0106] where P ck is the circulating current loss of the k-th strand of wire, and R dc is the resistance value of the stator winding 11;

[0107] Sum up the circulating current losses of all strands of wire to obtain the total circulating current loss P c .

[0108] Take the average effective value I av of the strand current in the stator winding 11, and calculate the basic copper loss of the stator winding 11 according to this average effective value I av of the strand current:

[0109]

[0110] where P dc is the basic copper loss of the stator winding 11.

[0111] Collect the voltage and current at both ends of the stator winding 11, and calculate the total power loss P of the stator winding 11 through a pre-established model.

[0112] Calculate the stator iron loss P Fe according to the empirical formula.

[0113] Based on the stator iron loss P Fe , the total circulating current loss P c , the basic copper loss P dc and the total power loss P, obtain the eddy current loss P eddy :

[0114] P eddy = P - P dc - P c - P Fe .

[0115] In summary, the structure of the present invention is simple, which can be equivalent to the change of leakage magnetic field in the slot, facilitating integration with other systems so as to achieve automation.

[0116] Although the present invention has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. Therefore, it should be understood that many modifications can be made to the exemplary embodiments, and other arrangements can be designed, as long as they do not deviate from the spirit and scope of the present invention defined by the appended claims. It should be understood that different dependent claims and the features described herein can be combined in a manner different from that described in the original claims. It should also be understood that the features described in connection with a single embodiment can be used in other described embodiments.

Claims

1. A multi-loss measurement device based on an equivalent true motor rotor magnetic field, characterized in that Comprising: A rectangular stator core (10), two exciting cores (12), a collection unit, a host computer (17), and two exciting units; The rectangular stator core (10) has the same pitch as the motor under test. A plurality of grooves are evenly formed on the surface of the rectangular stator core (10). Stator windings (11) are wound in the grooves at both ends. The two exciting cores (12) are both U-shaped. The two exciting cores (12) are respectively arranged at the openings of the grooves at both ends, and an air gap is left between the exciting core (12) and the rectangular stator core (10). An exciting coil (13) is wound on each exciting core (12); The two exciting units are respectively used to apply current to the stator winding (11) and the exciting coil (13); The collection unit is used to collect the magnetic field intensity of each strand of the stator winding (11) and send it to the host computer (17); The host computer (17) is used to construct a correlation equation between the magnetic field intensity of each strand and the strand current to obtain the current of each strand, and then calculate the total power loss, basic copper loss, total circulating current loss, and eddy current loss of the stator winding (11) based on the current of each strand.

2. The multi-loss measurement device based on the equivalent true motor rotor magnetic field according to claim 1, characterized in that, The collection unit includes: a magnetic field collector (14), a signal amplification circuit (15), and a signal conversion module (16). The magnetic field collector (14) includes a plurality of micro Hall sensors. A micro Hall sensor is provided at the end of each strand of the stator winding (11); The micro Hall sensor is used to collect the magnetic field intensity of the strand where it is located, and send the magnetic field intensity to the signal conversion module (16) after being amplified by the signal amplification circuit (15). The signal conversion module (16) performs analog-to-digital conversion on the amplified magnetic field intensity signal and then sends it to the host computer (17).

3. The multi-loss measurement device based on the equivalent true motor rotor magnetic field according to claim 2, characterized in that, The exciting unit includes a single-phase step-down transformer (18) and an adjustable AC power supply (19); In the exciting unit connected to the stator winding (11), its adjustable AC power supply (19) applies a known stable DC current to the stator winding (11) through the single-phase step-down transformer (18), collects the voltage at both ends of the stator winding (11), and then calculates the resistance value of the stator winding (11); In the exciting unit connected to the exciting coil (13), its adjustable AC power supply (19) applies current to the exciting coil (13) through the single-phase step-down transformer (18) to form a leakage magnetic field in the exciting core (12).

4. The multi-loss measurement device based on the equivalent true motor rotor magnetic field according to claim 2 or 3, characterized in that The host computer (17) is used to construct a correlation equation between the magnetic field intensity of each strand and the strand current to obtain the current of each strand, and then calculate the total power loss, basic copper loss, total circulating current loss, and eddy current loss of the stator winding (11) based on the current of each strand, including: Constructing a correlation equation between the current and magnetic field of each strand in the stator winding (11), and then calculating the current of each strand in the stator winding (11). Calculating the circulating current of each strand according to the current of each strand, and calculating the circulating current loss of each strand according to the circulating current of each strand; Obtain the average effective value of the strand current in the stator winding (11), and calculate the basic copper loss of the stator winding (11) according to the average effective value of the strand current; Under the action of the leakage magnetic field, collect the voltage and current at both ends of the stator winding (11), and calculate the total power loss of the stator winding (11) through a pre-established model; Calculate the stator iron loss according to the empirical formula; Obtain the eddy current loss based on the stator iron loss, circulating current loss, basic copper loss and total power loss.

5. The multi-loss measurement device based on the equivalent true motor rotor magnetic field according to claim 4, wherein The expression of the correlation equation between the current of each strand in the stator winding (11) and the magnetic field is as follows: Among them, the total number of strands in the stator winding (11) is 2n, I 2n is the current of the 2nth strand in the stator winding (11), B 2n is the magnetic field intensity collected by the 2nth micro Hall sensor, k (2n,2n) is the proportionality coefficient between the magnetic field intensity collected by the 2nth micro Hall sensor and the current of the 2nth strand; The expression for calculating the circulating current of each strand according to the current of each strand is as follows: I ck = I k - I av , Among them, I ck is the circulating current of the k-th strand, I k is the current of the k-th strand, k = 1, 2,..., 2n, I av is the average effective value of the strand current; The expression for calculating the circulating current loss of each strand according to the circulating current of each strand is as follows: Among them, P ck is the circulating current loss of the k-th strand, and R dc is the resistance value of the stator winding (11); Sum the circulating current losses of all strands to obtain the total circulating current loss P c .

6. The multi-loss measurement device based on the equivalent true motor rotor magnetic field according to claim 4, characterized in that, The expression for calculating the basic copper loss of the stator winding (11) according to the average effective value of the strand current is as follows: Among them, P dc is the basic copper loss of the stator winding (11), I av is the average effective value of the strand current, and R dc is the resistance value of the stator winding (11).

7. The multi-loss measurement device based on the equivalent real motor rotor magnetic field according to claim 4, characterized in that, The expression for obtaining the eddy current loss based on the stator iron loss, circulating current loss, basic copper loss and total power loss is as follows: P eddy = P - P dc -P c -P Fe , Among them, P eddy is the eddy current loss, P is the total power loss, P dc is the basic copper loss, P c is the total circulating current loss, P Fe is the stator iron loss.

8. A multi-loss measurement method based on an equivalent real motor rotor magnetic field, characterized in that Include: Prepare a rectangular stator core (10) with the same pole pitch or coil pitch as the motor under test. A plurality of grooves are evenly opened on the surface of the rectangular stator core (10). Wind the stator winding (11) in the grooves at both ends, and respectively set a U-shaped excitation core (12) at the notch of the grooves at both ends. There is an air gap between the excitation core (12) and the rectangular stator core (10). Wind the excitation coil (13) on each excitation core (12); Apply a known stable DC current to the stator winding (11), collect the voltage at both ends of the stator winding (11), and then calculate and obtain the resistance value of the stator winding (11); Apply a current to the excitation coil (13) to make the excitation core (12) form a leakage magnetic field. Under the action of this leakage magnetic field, collect the magnetic field intensity of each strand of the stator winding (11), construct the correlation equation between the current of each strand in the stator winding (11) and the magnetic field, and then calculate the current of each strand in the stator winding (11). Calculate the circulating current of each strand according to the current of each strand, calculate the total circulating current loss of the stator winding (11) according to the circulating current of each strand, obtain the average effective value of the strand current in the stator winding (11), and calculate the basic copper loss of the stator winding (11) according to the average effective value of the strand current. Collect the voltage and current at both ends of the stator winding (11), calculate the total power loss of the stator winding (11) through a pre-established model, calculate the stator iron loss according to the empirical formula, and obtain the eddy current loss based on the stator iron loss, total circulating current loss, basic copper loss and total power loss.

9. The multi-loss measurement method based on the equivalent true motor rotor magnetic field according to claim 8, wherein The expression of the correlation equation between the current of each strand in the stator winding (11) and the magnetic field is as follows: Among them, the total number of strands in the stator winding (11) is 2n, I 2n is the current of the 2nth strand in the stator winding (11), B 2n is the magnetic field strength collected by the 2nth micro Hall sensor, k (2n,2n) is the proportionality coefficient between the magnetic field strength collected by the 2nth micro Hall sensor and the current of the 2nth strand; The expression for calculating the circulating current of each strand according to the current of each strand is as follows: I ck = I k - I av , Among them, I ck is the circulating current of the k-th strand, and I k is the current of the k-th strand, where k = 1, 2,..., 2n, and I av is the average effective value of the strand current; The expression for calculating the circulating current loss of each strand according to the circulating current of each strand is as follows: Among them, P ck is the circulating current loss of the k-th strand, and R dc is the resistance value of the stator winding (11); The circulating current losses of all strands are summed to obtain the total circulating current loss P c .

10. The multi-loss measurement method based on the equivalent real motor rotor magnetic field according to claim 9, characterized in that The expression for calculating the basic copper loss of the stator winding (11) according to the average effective value of the strand current is as follows: Among them, P dc is the basic copper loss; The expression for obtaining the eddy current loss based on the stator iron loss, total circulating current loss, basic copper loss and total power loss is as follows: P eddy = P - P dc -P c -P Fe , Among them, P eddy is the eddy current loss, P is the total power loss, and P Fe is the stator iron loss.

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