Servo Motor Applications Parsing

By Author: nova king
Total Articles: 2
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DC asynchronous motor is not designed for low inertia and high acceleration response.
Do you really need the servo motor? Asynchronous motor with a feedback device to provide better solutions for special applications it? Look at the definition and performance attributes of servo motors and asynchronous motors, may be able to get an answer.

Servo motor system: servo system is not just a motor, it contains the controller, drive motors and feedback devices, closed-loop motion systems, usually with optical or magnetic encoder. Servo motor suppliers are always doing advertising, on conceptual confusion.

The servo motor is a permanent magnet (PM) synchronous machine, on behalf of brush or brushless permanent magnet motor. Its performance attributes and several other motor types are not the same. The permanent magnet synchronous motor has a high peak and a continuous torque, the drive servo system can be used in precision positioning system to the high acceleration and deceleration. Torque is usually directly related ...
... to the input current is proportional to the motor shaft speed and input voltage. The higher the input voltage, the faster the motor torque / speed curve is linear.

The air gap of the permanent magnet structure, and the motor is directly connected. Look at the configuration of the permanent magnet brushless motor, and a movable rotor (a permanent magnet) and the fixed stator coil in the magnetic interaction, so that the motor with torque and speed. The three-phase stator field alternating strengthened, the permanent magnet rotor and the stator of the rotating synchronous. A special electronic communication systems can be used to detect the position of the rotor in order to strengthen the stator coil. Precise positioning system, in addition to the very large motors used in most automotive applications and systems, should choose a permanent magnet brushless motor. When used in closed-loop torque, speed or positioning system, permanent magnet brushless motor is only a servo motor.

The same as the physical owner of the induction motor and permanent magnet brushless motor stator and rotor structure is completely different. The squirrel cage induction motor includes a series of aluminum or copper pieces, is embedded in the recess of the rotor structure and connected, through the large end of the short wing. These rotor short board and stator rotating field magnetic coupling induces new rotor domain, so that the motion of the rotor with the stator interactions. Synchronous stator slight gap exists between the slow rotor domain and the actual rotor speed, this speed gap leads to slip. Input frequency determines the motor speed.

For example, one of 60Hz the bipolar AC motor no load speed can reach to 3600rpm, while the four-pole AC motor speed is less than 1800rpm, and dependent on the slip rate. With the increase in the torque of the motor, slip increases and the rate of decline. AC induction motor to increase torque, the cost of reduced speed until the load reaches a critical point when the motor speed is suddenly reduced to zero. An inherent performance characteristics of the AC motor: small initial torque, and the no load when the motor starts.

This inherent torque - speed performance, with the advent of the eighties electric inverter completely changed. The function of the frequency converter is to use adjustable or variable drive to re-determine the torque - speed curve, in order to change the voltage and frequency, so that the AC induction motor system speed king.

Today's speed and positioning systems: high-performance drive continued progress has been made AC induction motors and permanent magnet brushless motor and drive more competitive in the market, but the permanent magnet brushless motor still ruled positioning control applications. Besides, the permanent magnet brushless motor is still factory gobble DC brush speed control 1kw (1.37hp) or lower wattage applications market.

How to Select: induction DC motor is not designed for low hysteresis and high acceleration response. It accounted for the vast majority of market share in applications from 100 watts to 100 watts of speed.
From 50kw (67hp) or greater system permanent magnet brushless motor for servo positioning system. Fixed or variable speed system, more use AC induction motor. The general solution is rare. The other motor is also good, but far from classic AC induction motors and the emerging permanent magnet brushless motor so successful.