What is the difference between stepper motor and servo motor?
The difference between stepping motor and servo motor1., the method of control is not synchronous, the motor is controlled by the number of pulses to control the rotation angle, a pulse corresponds to a step angle. The servo motor controls the angle of rotation by controlling the duration of the pulse.2. of the work equipment and work flow without stepping motor for power supply (required voltage given by the drive parameters), a pulse generator (now mostly plate), a stepping motor, a drive (drive set step angle angle, such as setting the step angle of 0.45 degrees then, to a pulse motor, go 0.45 degrees); its work flow is the stepper motor work normally requires two pulse: pulse signal of pulse and direction. The power supply required by the servo motor is a switch (relay, switch or relay card), a servo motor, and its working flow is a power connection switch, and then connect the servo motor.
4. torque frequency characteristics are not synchronous, the output torque of the motor decreases with the increase of speed, and will decline sharply at higher speed, so the maximum working speed is usually 300 ~ 600r/min. AC servo motor for constant torque output, that is, at its rated speed (generally 2000 or 3000 r/min), can output rated torque, at rated speed above the constant power output.5. overload capacity is not synchronous, the motor generally does not have overload capacity. AC servo motor has strong overload ability. Take Panasonic AC servo system as an example, it has the ability of speed overload and torque overload. Its maximum torque is 3 times of the rated torque, which can be used to overcome the inertia moment of the inertia load at the start moment. Stepper motor because without the overload ability, in the selection in order to overcome this inertia moment, often need to select large torque motor, and the machine during normal operation and does not need so large torque, the torque will appear the phenomenon of waste.6. speed response performance of asynchronous motor, from static acceleration to working speed (usually hundreds of revolutions per minute), need 200 ~ 400ms. The acceleration performance of AC servo system is better. The Panasonic MSMA400W AC servo motor is taken as an example, from static acceleration to its rated speed of 3000 r/min. Only a few MS, can be used for rapid start and stop control.
3. low frequency characteristics of asynchronous motor at low speed prone to low-frequency vibration phenomenon. Vibration frequency is related to load and drive performance. Vibration frequency is generally considered as half of the no-load take-off frequency of motor. The low frequency vibration, which is determined by the working principle of the stepper motor, is very harmful to the normal operation of the machine. When stepping motor works at low speed, damping technology should be adopted to overcome low frequency vibration, such as adding damper on motor or subdividing technology on drive. AC servo motors operate very smoothly and do not vibrate even at low speeds. AC servo system has resonance suppression function, it can cover mechanical rigidity shortage, and the system has frequency analysis function (FFT), it can detect the resonance point of the machine, so that it is easy to adjust the system.
