Motor cogging torque testing system and method

Abstract

The invention relates to a motor cogging torque testing system and method, and relates to the technical field of motor testing. The system comprises a dragging unit, a torque sensing unit, a control and data acquisition unit and an auxiliary structure, the dragging unit comprises a hollow cup motor, an inertia disc and a harmonic reducer, the hollow cup motor serves as a power source, the inertia disc is fixedly connected to an output shaft of the hollow cup motor, and the harmonic reducer is connected with the inertia disc. A first coupler is arranged between the inertia disc and the harmonic reducer, and the input end of the harmonic reducer is connected with an output shaft of a hollow cup motor provided with the inertia disc through the first coupler. The method and the device have the effect of solving the problems of large dragging end interference and difficult low-speed and stable-speed in the existing test scheme.

Description

Technical Field

[0001] This application relates to the field of motor testing technology, and in particular to a motor cogging torque testing system and method based on zero cogging drag and inertia-stabilized speed. Background Technology

[0002] Cogging torque is one of the key characteristics for evaluating permanent magnet brushless motors, and its measurement accuracy directly affects the optimized design and application of the motor. For testing cogging torque, existing solutions mostly use traditional servo motors as the drag source, but the inherent cogging torque and torque fluctuations of these motors can introduce interference, leading to distorted measurement results. In addition, maintaining absolute stability of the dragging speed under the extremely low speed (e.g., 0.1-5 RPM) required for testing, and avoiding the impact of speed fluctuations on the test results, is a huge challenge. Although direct drive systems can avoid the problems caused by reduction mechanisms, they are expensive and have limited torque output. Therefore, there is an urgent need for a cogging torque testing solution that is moderately cost-effective, can completely eliminate drag-end interference, and can achieve ultra-smooth dragging. Summary of the Invention

[0003] To address the issues of significant interference at the dragging end and difficulty in achieving stable low-speed operation in existing testing methods, this application provides a motor cogging torque testing system and method.

[0004] Firstly, the motor cogging torque testing system provided in this application adopts the following technical solution: A motor cogging torque testing system includes a dragging unit, a torque sensing unit, a control and data acquisition unit, and auxiliary structures. The dragging unit includes a coreless motor, an inertia disk, and a harmonic reducer. The coreless motor serves as a power source, and the inertia disk is fixedly connected to the output shaft of the coreless motor. A first coupling is provided between the inertia disk and the harmonic reducer, and the input end of the harmonic reducer is connected to the output shaft of the coreless motor on which the inertia disk is mounted through the first coupling.

[0005] By adopting the above technical solutions, the coreless motor, as a power source, fundamentally eliminates its own cogging effect and hysteresis loss through its coreless rotor structure, providing a smooth torque output with almost no fluctuations. The inertia disk is used to suppress the motor's own minute torque pulsations and high-frequency disturbances in the transmission chain, and its function is equivalent to a mechanical low-pass filter, greatly enhancing the system's stability under ultra-low speed operation. The harmonic reducer has the characteristics of zero backlash, high rigidity, and high single-stage reduction ratio. On the one hand, it converts the high-speed, low-torque of the coreless motor into the low-speed, high-torque required for testing. On the other hand, it further isolates any minute disturbances that may exist at the dragging end, thus effectively solving the problems of large interference at the dragging end and difficulty in stabilizing the speed at low speed in existing solutions.

[0006] Preferably, the torque sensing unit includes a second coupling, a high-precision torque sensor, and a third coupling. The high-precision torque sensor is connected to the output end of the harmonic reducer through the second coupling, and the high-precision torque sensor is connected to the motor under test through the third coupling.

[0007] By adopting the above technical solution, a high-precision torque sensor is set up to collect the torque signal of the motor under test in real time during the rotation process. It also has a high-precision speed signal output function, which can further improve the detection accuracy.

[0008] Preferably, the control and data acquisition unit includes a servo driver, a data acquisition card, and host computer software. The data acquisition card is communicatively connected to a high-precision torque sensor, the data acquisition card is communicatively connected to the host computer software, and the servo driver is electrically connected to the host computer software.

[0009] By adopting the above technical solution, the servo driver is used to precisely control the speed of the coreless motor; the data acquisition card synchronously acquires signals from the high-precision torque sensor and encoder; and the host computer software filters, analyzes, and visualizes the data.

[0010] Preferably, an output flange is provided between the harmonic reducer and the second coupling.

[0011] By adopting the above technical solution, setting an output flange can effectively improve the stability of torque output.

[0012] Preferably, the auxiliary structure includes a high-rigidity mounting base and a motor environment chamber.

[0013] By adopting the above technical solutions and setting up auxiliary structures to reduce the interference of external vibration and temperature changes on the test results, it helps to improve the stability and safety of the equipment during the test process.

[0014] Secondly, this application also provides a method for testing the cogging torque of a motor, comprising the following steps: System startup: The control and data acquisition unit instructs the hollow cup motor to run, so that its speed reaches the extremely low constant speed required by the test motor; Inertial speed stabilization: The torque output by the hollow cup motor drives the inertia disk to rotate. The large inertia characteristic of the inertia disk smooths out small fluctuations and forms a stable rotational kinetic energy source. Precision deceleration: After the smooth rotary motion is reduced in speed by the harmonic reducer to increase torque, it drives the brushless motor under test to rotate at a constant speed through the third coupling. Data acquisition and processing: A high-precision torque sensor detects and records torque changes in real time. The acquired raw data is processed by filtering algorithms to remove noise and extract the pure cogging torque waveform generated by the motor under test. Peak value, period and spectrum analysis are then performed.

[0015] In summary, this application includes at least one of the following beneficial technical effects: 1. The system of this application has ultra-high precision and almost zero interference at the drag end, achieving a breakthrough in testing the cogging torque of motors at the millinewton level, and the measurement results truly reflect the characteristics of the motor under test; 2. The system of this application has ultra-stable low speed, and a unique electromechanical speed stabilization scheme achieves ultra-high stability at extremely low speeds; 3. The system of this application has high reliability. The mechanical speed stabilization method reduces the bandwidth requirements of the control loop, making the system more stable. 4. The system of this application has strong versatility. By replacing the harmonic reducer and inertia disk of different specifications, it can be adapted to motor testing from millinewtons to several Newton-meters. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of a motor cogging torque testing system according to an embodiment of this application.

[0017] Figure 2 This is a flowchart of a method for testing the cogging torque of a motor according to an embodiment of this application.

[0018] Explanation of reference numerals in the attached diagram: 1. Dragging unit; 11. Hollow cup motor; 12. Inertia disk; 13. Harmonic reducer; 14. First coupling; 15. Output flange; 2. Torque sensing unit; 21. Second coupling; 22. High-precision torque sensor; 23. Third coupling; 3. Control and data acquisition unit; 31. Servo driver; 32. Data acquisition card; 33. Host computer software; 4. Auxiliary structure; 41. High-rigidity mounting base; 42. Motor environmental chamber. Detailed Implementation

[0019] The following is in conjunction with the appendix Figure 1-2 This application will be described in further detail.

[0020] This application discloses a motor cogging torque testing system. (Refer to...) Figure 1 It includes a drag unit 1, a torque sensing unit 2, a control and data acquisition unit 3, and an auxiliary structure 4.

[0021] Reference Figure 1The dragging unit 1 includes a hollow cup motor 11, an inertia disk 12, and a harmonic reducer 13. The hollow cup motor 11 serves as a power source. The inertia disk 12 is fixedly connected to the output shaft of the hollow cup motor 11. A first coupling 14 is provided between the inertia disk 12 and the harmonic reducer 13. The input end of the harmonic reducer 13 is connected to the output shaft of the hollow cup motor 11 on which the inertia disk 12 is mounted through the first coupling 14.

[0022] Reference Figure 1 The torque sensing unit 2 includes a second coupling 21, a high-precision torque sensor 22, and a third coupling 23. The high-precision torque sensor 22 is connected to the output end of the harmonic reducer 13 through the second coupling 21. In this embodiment, an output flange 15 is provided between the harmonic reducer 13 and the second coupling 21 to improve the stability of torque output. The high-precision torque sensor 22 is connected to the motor under test through the third coupling 23.

[0023] Reference Figure 1 The control and data acquisition unit 3 includes a servo driver 31, a data acquisition card 32, and host computer software 33. The data acquisition card 32 is communicatively connected to the high-precision torque sensor 22 and the host computer software 33. The servo driver 31 is electrically connected to the host computer software 33. The servo driver 31 is used to precisely control the speed of the hollow cup motor 11. The data acquisition card 32 synchronously acquires signals from the high-precision torque sensor 22 and the encoder. The host computer software 33 filters, analyzes, and visualizes the data.

[0024] Reference Figure 1 The auxiliary structure 4 includes a high-rigidity mounting base 41 and a motor environment chamber 42. The auxiliary structure 4 is set up to reduce the interference of external vibration and temperature changes on the test results, which helps to improve the stability and safety of the equipment during the test.

[0025] The implementation principle of the motor cogging torque testing system in this application embodiment is as follows: The hollow cup motor 11 of this application serves as a power source. Its coreless rotor structure fundamentally eliminates its own cogging effect and hysteresis loss, providing a smooth torque output with almost no fluctuations. The inertia disk 12 is used to suppress the motor's own small torque pulsation and the high-frequency disturbance of the transmission chain. Its function is equivalent to a mechanical low-pass filter, which greatly enhances the stability of the system under ultra-low speed operation. The harmonic reducer 13 has the characteristics of zero backlash, high rigidity, and high single-stage reduction ratio. On the one hand, it converts the high-speed low torque of the hollow cup motor 11 into the low-speed high torque required for testing. On the other hand, it further isolates any small disturbances that may exist at the drag end, thereby effectively solving the problems of large interference at the drag end and difficulty in stabilizing the speed at low speed in the existing solution.

[0026] This application also discloses a method for testing the cogging torque of a motor, referring to... Figure 2 It includes the following steps: S1: System Start-up: The control and data acquisition unit 3 instructs the hollow cup motor 11 to run, so that its speed reaches the corresponding test requirements of the motor running at a very low constant speed. S2: Inertial speed stabilization: The torque output by the hollow cup motor 11 drives the inertia disk 12 to rotate. The large inertia characteristic of the inertia disk 12 smooths out small fluctuations and forms a stable rotational kinetic energy. S3: Precision deceleration: After the smooth rotary motion is reduced in speed by the large torque of the harmonic reducer 13, it drives the brushless motor under test to rotate at a constant speed through the third coupling 23. S4: Data Acquisition and Processing: The high-precision torque sensor 22 detects and records torque changes in real time. The acquired raw data is processed by filtering algorithms to remove noise and extract the pure cogging torque waveform generated by the motor under test. Peak value, period and spectrum analysis are then performed.

[0027] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A motor cogging torque test system, characterized by: It includes a dragging unit, a torque sensing unit, a control and data acquisition unit and an auxiliary structure, the dragging unit includes a hollow cup motor, an inertia disc and a harmonic reducer, the hollow cup motor serves as a power source, the inertia disc is fixedly connected to an output shaft of the hollow cup motor, a first coupling is arranged between the inertia disc and the harmonic reducer, and an input end of the harmonic reducer is connected with the output shaft of the hollow cup motor through the first coupling.

2. The motor cogging torque test system of claim 1, wherein: The torque sensing unit includes a second coupling, a high-precision torque sensor and a third coupling, the high-precision torque sensor is connected with an output end of the harmonic reducer through the second coupling, and the high-precision torque sensor is connected with the motor to be measured through the third coupling.

3. A motor cogging torque test system as set forth in claim 2, characterized by: The control and data acquisition unit includes a servo driver, a data acquisition card and upper computer software, the data acquisition card is in communication connection with the high-precision torque sensor, the data acquisition card is in communication connection with the upper computer software, and the servo driver is electrically connected with the upper computer software.

4. The motor cogging torque test system of claim 2, wherein: An output flange is arranged between the harmonic reducer and the second coupling.

5. The motor cogging torque test system of claim 1, wherein: The auxiliary structure includes a high-rigidity mounting base and a motor environment bin.

6. A method of testing cogging torque of an electric machine, the method comprising: It includes the following steps: System starting: the control and data acquisition unit instructs the hollow cup motor to run, so that the rotating speed of the hollow cup motor reaches the corresponding test requirement of the motor to run at a very low constant rotating speed; Inertia speed stabilization: the torque output by the hollow cup motor drives the inertia disc to rotate, and the large inertia characteristic of the inertia disc smooths out slight fluctuations to form a stable rotating power source; Precise speed reduction: after the smooth rotating movement is passed through the harmonic reducer to increase the torque and reduce the rotating speed, the brushless motor to be measured is driven to rotate at a constant speed through the third coupling; Data acquisition and processing: the high-precision torque sensor detects and records the torque change in real time, the original data collected are processed through filtering algorithms, after removing the noise, the pure tooth slot torque waveform generated by the motor to be measured is extracted, and peak value, period and frequency spectrum analysis are performed.

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