The three words of torque, torque and torque are often used by engineers in the industry. Everyone thinks that these three are the same concept. When testing, they only pay attention to their ratings and peak values. Today, let's analyze the differences between the three and related test items.
First, the source and difference of torque, torque and torque
When it comes to torque, we immediately think of leverage. The product of the force and the distance of the fulcrum perpendicular to the direction of action of the force is called the moment. The unit of torque is Newton-meter.
Figure 1 Lever torque
Torque and torque are the moments of rotation. For a rotating object, if the center of the rotating shaft is regarded as a fulcrum, the product of the force on the circumference of the rotating object and the distance between the center of the rotating shaft and the direction of the force is called torque. When a cylindrical object is subjected to force without rotation, the object has only elastic deformation due to the torsion force. The torque at this time is called torque.
Figure 2 Torque, torque
Therefore, it can only be called "torque" strictly in the running motor. It is not appropriate to use "torque" or "torque". However, it is customary to use these three names for a long time, at least for six or seventy years, so no one deliberately corrects it.
Second, the method and trend of motor torque measurement
At present, the torque of the measuring motor in the industry is generally measured directly by the torque measuring instrument. There are many industry leading edge measurement items for the torque of the motor, such as moment angle characteristics, torque fluctuation, cogging torque, friction torque test, etc. .
For a stepping motor or a switched reluctance motor, particular concern is the angle θ between the stator magnetomotive force FS and the rotor magnetomotive force Fr, rather than the power angle σ well known in conventional synchronous motors. The angle θ in the step-synchronous motor is a very important parameter, called the moment angle, and the relationship between the motor torque and the moment angle becomes the moment angle characteristic. The following figure shows the moment angle characteristic curve obtained by the test of the MPT1000 motor test system of Zhiyuan Electronics.
The motor exhibits a small fluctuation value ΔM due to the change of its output torque with the armature angular position. The torque fluctuation coefficient is usually used to measure this quality of the torque motor. Zhiyuan Electronics uses the load motor to apply the maximum torque specified in the continuous working area to the motor under test, control the motor to run at the lowest speed, use the torque sensor to record the torque of the motor during one week of operation, and record the maximum torque and minimum torque. , the torque fluctuation coefficient can be calculated.
