Category
BLDC Motor Supplier
info@bldcmotor.org
Home » BLDC Motor Wiki » How to Test the Torque of BLDC Motor?
How to Test the Torque of BLDC Motor?
Torque is an important parameter of the brushless DC motor test. In the BLDC motor efficiency evaluation, torque is an indispensable variable to be measured, and the accuracy of the torque measurement is directly linked to the accuracy of the electric motor's efficiency test. When the transmission method is used to transmit the torque, the physical parameters of electric components will undergo certain degree of changes. The correspondence between the change and the torque can be utilized to measure the torque. According to different physical parameters, transmission can be further divided into the magnetic elastic type, strain type, vibrating wire type, photoelectric type, etc. Currently, the transmission method has found the widest applications in the torque measurement field.
How to test photoelectric torque?
Fix two pieces of round-disk grating with the same number of open holes onto the rotating axis. Fix the photoelectric components and fixed light source onto two sides of the grating. When the rotating axis has no torque, the bright and dark patterns of the two pieces of gratings will be separated to fully block the light path. In this way, there will be no light rays cast on light sensors, and no electric signals will be output. Under the torque effect, the relative corner is generated by the cross-section of two round-disk gratings under the torque effect. The bright and dark patterns will be partially overlapped. Some light rays penetrate through the grating to cast onto the light sensors and to output electric signals. The larger the torque value is, the larger the torsion angle is, the stronger the light ray intensity is cast onto the light sensors, and the stronger the output electric signals is. By measuring the output electric signals, we can obtain the value of the externally imposed torque.
Advantages of this method include fast response and real-time monitoring of the BLDC motor torque. Its disadvantages include complex structure, difficult static labeling, poor reliability, poor anti-interference, and vulnerability of the measurement precision to temperature changes. This method is not applicable to the torque measurement when the machine is just started or when the axis is rotating at a slow speed.
How to test magnetoelectric torque?
Install two identical gears on the elastic axis. Integrate the magnetic core and the coil into a signal collection system. Reserve a small interval between the gear top and the magnetic core. When the axis is rotating, two coils can perceive the two alternating electromotive forces, and the alternating electromotive force is just related to the magnetic core relative position and intersectional position of the two gears. By detecting the value of the electromotive force, we can obtain the corresponding torque value.
Advantages of this method include high precision, low cost, and reliable performance. It adopts non-contact measurement, which requires no power source and intermediate transmission link. Its disadvantages include complex structure, limited frequency response, manufacturing difficulty, and long response. The corresponding sensor dimensions and mass are large. When the speed is slow, the signal is small. When the speed is fast, the dynamic balance is difficult to achieve. The magnetoelectric torque measurement method is applicable to measurement of the torque of a larger corner displacement and measurement of the launch and low-speed torque. Since the dynamic characteristics are poor, it is inapplicable to the torque measurement of the high-speed rotating axis.
How to test vibrating-wire torque?
The functional relationship between the inherent frequency and tension of the vibration string transforms the force into the electric quantity, which first measures the electric quantity into the force and then works out the corresponding torque value.
This method can directly make use of the transmission shaft as the torsion axis for measurement. The frequency signal transmission can be adopted, which has a favorable anti-interference performance. The sensor part can be separated from the force measurement axis for the convenience of measuring the ship or vehicle. However, it also has its disadvantages, including a complex structure, a low sensitivity, a low measurement accuracy and a high requirement of the elastic axis’s elastic deformation. This method is applicable to the torque measurement of the large-scale rotating axis but not applicable to measurement of the high-speed rotating axis.
How to test magnetoelastic torque?
Magnetic elastic torque measurement method is a method which makes use of the magnetoelastic effect of the ferromagnetic materials and other alloy materials to realize the torque measurement. Impose the torque on the elastic axis of ferromagnetic materials in the magnetic field. Changes of the magnetic conductivity can reflect changes of the ferromagnetic materials’ magnetization intensity. Therefore, by measuring changes of the magnetic conductivity, the torque signals can be obtained.
Advantages of this method include high sensitivity, good stability, large non-contact measurement and output power, fast response, good overload protection, convenient installation, strong resistance to interference, simple structure and circuit, and capability to work under the harsh environment. Its disadvantages include the error of the "arc modulation", which has limited its applications; the magnetic conductivity distributed along the surroundings of the torque axis has inherent deviation; the measurement accuracy is low, and the strain value measured is just the strain value of the magnetostriction materials, which is deviated from the required torque value. So far, the magnetoelastic torque measurement method has found wide applications in the field of ship power equipment, steel rolling, petroleum drilling machines and CNC vehicles.
How to test strain torque?
The torque will generate strain of the transmission axis, and the strain is in proportion to the torque value. Therefore, the value of the corresponding torque can be measured via the resistance strain gauge. When the torque is imposed on the transmission axis, the torque distortion will happen. The maximum shearing strain is generated at the direction forming an angle of 45°on the axis. In this direction, the resistance gauge can be pasted to test the torque value exerted on the transmission axis.
Advantages of the strain torque measurement method include a simple structure, high sensitivity, strong adaptability, low cost, convenient operation, mature technology, wide applications, high measurement precision, fast response, reliable and steady performance, efficient temperature compensation, and adaptability to the harsh environment. As to its disadvantages, factors, including moisture, temperature and binder, can influence the measurement accuracy. At the same time, the anti-interference is poor, so this measurement method is not applicable to the torque measurement of high-speed rotating axis.
How to test photoelectric torque?
Fix two pieces of round-disk grating with the same number of open holes onto the rotating axis. Fix the photoelectric components and fixed light source onto two sides of the grating. When the rotating axis has no torque, the bright and dark patterns of the two pieces of gratings will be separated to fully block the light path. In this way, there will be no light rays cast on light sensors, and no electric signals will be output. Under the torque effect, the relative corner is generated by the cross-section of two round-disk gratings under the torque effect. The bright and dark patterns will be partially overlapped. Some light rays penetrate through the grating to cast onto the light sensors and to output electric signals. The larger the torque value is, the larger the torsion angle is, the stronger the light ray intensity is cast onto the light sensors, and the stronger the output electric signals is. By measuring the output electric signals, we can obtain the value of the externally imposed torque.
Advantages of this method include fast response and real-time monitoring of the BLDC motor torque. Its disadvantages include complex structure, difficult static labeling, poor reliability, poor anti-interference, and vulnerability of the measurement precision to temperature changes. This method is not applicable to the torque measurement when the machine is just started or when the axis is rotating at a slow speed.
How to test magnetoelectric torque?
Install two identical gears on the elastic axis. Integrate the magnetic core and the coil into a signal collection system. Reserve a small interval between the gear top and the magnetic core. When the axis is rotating, two coils can perceive the two alternating electromotive forces, and the alternating electromotive force is just related to the magnetic core relative position and intersectional position of the two gears. By detecting the value of the electromotive force, we can obtain the corresponding torque value.
Advantages of this method include high precision, low cost, and reliable performance. It adopts non-contact measurement, which requires no power source and intermediate transmission link. Its disadvantages include complex structure, limited frequency response, manufacturing difficulty, and long response. The corresponding sensor dimensions and mass are large. When the speed is slow, the signal is small. When the speed is fast, the dynamic balance is difficult to achieve. The magnetoelectric torque measurement method is applicable to measurement of the torque of a larger corner displacement and measurement of the launch and low-speed torque. Since the dynamic characteristics are poor, it is inapplicable to the torque measurement of the high-speed rotating axis.
How to test vibrating-wire torque?
The functional relationship between the inherent frequency and tension of the vibration string transforms the force into the electric quantity, which first measures the electric quantity into the force and then works out the corresponding torque value.
This method can directly make use of the transmission shaft as the torsion axis for measurement. The frequency signal transmission can be adopted, which has a favorable anti-interference performance. The sensor part can be separated from the force measurement axis for the convenience of measuring the ship or vehicle. However, it also has its disadvantages, including a complex structure, a low sensitivity, a low measurement accuracy and a high requirement of the elastic axis’s elastic deformation. This method is applicable to the torque measurement of the large-scale rotating axis but not applicable to measurement of the high-speed rotating axis.
How to test magnetoelastic torque?
Magnetic elastic torque measurement method is a method which makes use of the magnetoelastic effect of the ferromagnetic materials and other alloy materials to realize the torque measurement. Impose the torque on the elastic axis of ferromagnetic materials in the magnetic field. Changes of the magnetic conductivity can reflect changes of the ferromagnetic materials’ magnetization intensity. Therefore, by measuring changes of the magnetic conductivity, the torque signals can be obtained.
Advantages of this method include high sensitivity, good stability, large non-contact measurement and output power, fast response, good overload protection, convenient installation, strong resistance to interference, simple structure and circuit, and capability to work under the harsh environment. Its disadvantages include the error of the "arc modulation", which has limited its applications; the magnetic conductivity distributed along the surroundings of the torque axis has inherent deviation; the measurement accuracy is low, and the strain value measured is just the strain value of the magnetostriction materials, which is deviated from the required torque value. So far, the magnetoelastic torque measurement method has found wide applications in the field of ship power equipment, steel rolling, petroleum drilling machines and CNC vehicles.
How to test strain torque?
The torque will generate strain of the transmission axis, and the strain is in proportion to the torque value. Therefore, the value of the corresponding torque can be measured via the resistance strain gauge. When the torque is imposed on the transmission axis, the torque distortion will happen. The maximum shearing strain is generated at the direction forming an angle of 45°on the axis. In this direction, the resistance gauge can be pasted to test the torque value exerted on the transmission axis.
Advantages of the strain torque measurement method include a simple structure, high sensitivity, strong adaptability, low cost, convenient operation, mature technology, wide applications, high measurement precision, fast response, reliable and steady performance, efficient temperature compensation, and adaptability to the harsh environment. As to its disadvantages, factors, including moisture, temperature and binder, can influence the measurement accuracy. At the same time, the anti-interference is poor, so this measurement method is not applicable to the torque measurement of high-speed rotating axis.
Post a Comment:
You may also like:
