Used in precision machine tools and robots have any characteristic of servo motor
Feeding mechanical and electrical machine is simply an electric motor, but why want to call a servo motor?
Comes from Greek, the word 'server' is the meaning of 'slave', servo motor can be understood as 'absolutely obey the control signal of motor command, didn't receive the control signal, absolutely can't turn, when the received signal must immediately reach the rated speed, and the signal to stop, speed must be in a very short time to 0.
In 1978, Germany Rexroth Indramat division in Hanover trade fair officially launched MAC permanent magnet ac servo motor and drive system, marks a new generation of ac servo technology has entered the stage of practical application.
Ac servo motor in zero drift, but early simulation system anti-interference, reliability, accuracy and flexibility, as well as insufficient, can't fully meet the requirements of motion control, until the new application of DSP, the digital control system, servo machine in precision machine tools, elevators, medical equipment, computer peripherals, the robot almost all industries have a wide range of applications.
Japan precision machine tool for our country in precision machine tools and robots behind (in the two aspects of the status quo, not domestic regression of high-end servo motor, it is also one of people's heart.
Servo motor on the function and structure and the stepping motor is similar, but both have the very big difference in performance.
Stepping motor servo motor structure chart in the first place, the precision of the servo motor and stepper motor control different two-phase hybrid stepper motor step Angle of the general is 1.
Step 9 °, 5 phase hybrid stepping motor is apart from the Angle of general to 0.
And control precision of the ac servo motor by the motor shaft after the rotary encoder, for with 17 encoder of the motor, drive round each receive 131072 pulse motor, i. e. the pulse equivalent of 360 ° / 131072 = 0.
Interval Angle 0027466 °, is 1.
8 ° stepper motor of 1/655 of the pulse equivalent.
Second, servo motor and stepper motor low frequency characteristics of the asynchronous motor at low speed is easy to appear low frequency vibration phenomenon, the working principle of stepper motor determines the low frequency vibration phenomenon is very bad for the normal operation of the machine, step motor is fixed resonance point, a lot of stepper driver by automatically calculate the vibration points, to adjust the control algorithm to achieve the purpose of suppressing the vibration.
Ac servo motor running smoothly, even in the low speed also won't appear when the vibration phenomenon.
Ac servo system has a resonance suppression function, can make up for the insufficient rigidity of the machinery, and the system has the function of frequency resolution (
, can detect the mechanical resonance point, is advantageous for the system adjustment.
Servo system function contains resonance suppression to suppress the structural vibration and damping vibration of two parts.
Resonance damping vibration suppression third, servo motor and stepper motor torque-speed characteristics not synchronous motor output torque increases with speed decreases, and at a high speed when they fell sharply, so its maximum working speed is in commonly 300 ~ 600 RPM.
Ac servo motor for constant torque output, that is, in its rated speed (
General is 2000 RPM and 3000 RPM)
Less than, can be rated output torque, in for a constant power output above the rated speed.
Under the same size of servo motor and the speed of the stepper motor torque characteristic is the fourth, servo motor and stepper motor overload capacity is not synchronous motor is generally not have overload ability.
Ac servo motor has a strong ability of overload.
M2 ac servo system, for example, it has the speed overload and torque overload capacity.
The maximum torque for two to three times the rated torque, can be used to overcome inertia load at startup moments of inertia moment.
Fifth, servo motor and stepper motor operation performance is not synchronous motor control for the open loop control, start frequency is too high or too much load is easy to appear out of step or locked-rotor phenomenon, stops frequently occur high speed overshoot phenomenon, so as to ensure the control accuracy, should handle the ascending and descending speed problem.
Ac servo drive system for closed-loop control, the actuator can be directly to the motor encoder feedback signal sampling, internal position loop and speed loop, general won't appear the out of step of step motor or overshoot phenomenon, more reliable control performance.
Sixth, servo motor and stepper motor speed response performance of the asynchronous motor to accelerate from 0 to speed (
Generally for a few hundred revolutions per minute)
Need to 200 ~ 400 milliseconds.
Acceleration of the ac servo system is better, to wong chi 400 w ac servo motor as an example, from the static accelerated to the rated speed 3000 RPM it takes only a few milliseconds, can be used for quick start-stop control occasions.
Very high demand in some occasions, must use performance is far higher than that of step motor servo motor.
Although China has the world's most complete industrial categories, but most are 'unconstrained ci school' field, there is a great gap for the accumulation of high-end products.