What is the difference between a step motor and a servo motor and a three-phase asynchronous machine?
Fundamental classification of electrical machinery 1, divide by the input current Dc motor Principle: the input current is dc through the brush and the commutator segment so that the motor rotor continuously gets the same current. Advantage: the speed regulation scope of dc motor is broad, the speed adjustment characteristic is smooth, the overload ability is stronger, the starting and braking torque is larger. Disadvantages: because the brush is easily worn, the motor life is not high. And dc motor is relatively low power. 2) alternator Principle: the input current of ac, electromagnet for instead of permanent magnets, the ac signal is loaded into the motor stator rotating magnetomotive force generated, so that the motor winding is constantly cutting magnetic field force. Advantage: high life, high power, not easily damaged by large current shock, cooling braking is more convenient. Disadvantages: low precision and low speed regulation performance.
Principle of servo motor, servo motor, also known as force motor, divided into two major categories of dc and ac servo motor, servo motor inside the rotor is a permanent magnets, drive control of U/V/W three-phase electric form of electromagnetic field, under the action of rotating rotor in this field, at the same time, the motor with encoder feedback signal to drive, drive according to the feedback value compared with the target, adjust the Angle of the rotor rotation. The accuracy of the servo motor is determined by the accuracy of the encoder (line count). Advantages: because the servo motor coder has the inner closed loop, so the control precision is very high, it can run normally at high speed. The drive can communicate directly with the top machine. Disadvantages: high price, long period of supply of imported goods, high maintenance cost.
Step motor principle: stepping motor is an actuator that converts electrical impulses into angular displacement. Popular point: when the stepper driver receives a pulse signal, it is driving a stepper motor according to set the direction of a fixed Angle (and the step Angle). It can control the amount of angular displacement by controlling the number of pulses, so as to achieve accurate positioning. At the same time, the speed and acceleration of the motor can be controlled by controlling the pulse frequency to achieve the goal of speed adjustment. Advantages: because of the digital input, the accuracy of the motor is greatly improved, the speed and acceleration control are easy to achieve and the control effect is better. Disadvantages: poor performance at high speed, high complexity in controller drive circuit. The price is higher than the traditional machine
Divided by means of control 1) conventional machine Principle: the analog input, which is the direct power of the armature winding, is completely dependent on the control of the motor Input current and voltage control. Advantage: the price is low, the control circuit is simple, the power can be very big. Disadvantages: the accuracy is very low, the speed adjustment curve is very rough.
Asynchronous motor principle: when the motor stator winding into the alternating current (ac), will produce a rotating magnetic field, the rotating magnetic field cutting rotor winding, thus produce induced current in the rotor winding, rotor of current-carrying conductor under the effect of the stator rotating magnetic field will produce electromagnetic force, as to form the electromagnetic torque on the motor shaft, motor rotation, and the motor rotation direction is the same as the rotating magnetic field direction. Because the rotor of the asynchronous motor is rotating with the stator rotating field in the same direction, different rotational speed, there is a slip rate, so it is called asynchronous motor. advantages Compared with other electric motors, the structure is simple, manufacturing is convenient, the performance is good, and can save all kinds of materials, the price is cheap. disadvantages The power factor lags, low power factor is low, and the speed adjustment performance is slightly worse.
