“AC motor” for implementing mechanical energy and conversion of AC power. Due to the great development of AC power systems, AC motor has become the most commonly used motors. DC compared with the AC motor, since there is no commutator (see commutated DC motor), the structure is simple, easy to manufacture, is strong, easy to make high-speed motors, high voltage, high current, high capacity. Covering a large range of AC electrical power from a few watts to hundreds of thousands of kilowatts, or even millions of kilowatts. In the early 1980’s, the largest steam turbine generator has reached 1.5 million kilowatts. AC motor is a Serbian-American scientist Nikola Tesla invention.
1. The inventors AC motor
Serb AC motor by American scientist Nikola Tesla invention.
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AC motor 2 Category
According to statistics, the AC motor can be classified in two ways:
3 describes the alternating current motor shaft
is an AC motor very broad classification, the type of the motor itself is very large, AC motor itself can be divided into low speed with high speed, low speed can be called low-speed motors, AC low-speed motor, speed can be called high-speed motor, high-speed motor, exchange high-speed motor, high speed motor and can be called a spindle, high-speed spindle and so on.
Electric spindles: electric spindle is the spindle with the new technology integrated spindle motor in recent years appeared in the field of CNC machine tools, linear motor technology with it, high-speed cutting tool technology together, will bring high-speed machining into a new era. It is a spindle assembly comprising a spindle itself and its accessories: electric spindle, the high-frequency inverter device, oil mist lubrication, cooling means, built-in encoder, tool changer.
Technology
The spindle fused: High speed bearing technology: electric spindle usually composite ceramic bearing, wear resistant, the conventional bearing life is several times; sometimes with electromagnetic levitation bearing or hydrostatic bearing, the inner and outer circle no contact, theoretically unlimited lifetime;
High speed motor technology: electric spindle motor is the product together with the shaft, a rotor is the rotating part of the motor shaft, in theory, it can be regarded as a high-speed electric spindle motor. The key technology is the high speed balancing;
Lubrication: Spindle commonly used lubricating oil lubrication time quantitative; may be lubricated with grease, but the corresponding rate to be discounted. The so-called timing is every certain time interval Note oil. The so-called quantified, it is called by means of the dosing valve to precisely control the amount of oil in each lubricating oil. And lubricating oil, the lubricating oil refers carrying compressed air, is blown into the ceramic bearings. Fuel control is very important, too, would not achieve lubrication; too much, bearing in high-speed rotation due to oil and heat resistance.
The cooling device: electric spindle in order to quickly heat the high-speed operation, typically through an outer wall of the spindle to circulate the coolant, the cooling effect of the device is to maintain the temperature of the coolant.
pulse coder built: To achieve the automatic tool change and a rigid tapping, spindle built a pulse encoder to achieve accurate phase angle control and the feed fit.
Automatic Tool Changer: For use in machining centers, equipped with an automatic tool change spindle apparatus comprises a dish spring, Broach et cylinder;
High speed tool chucking manner: Canton is familiar with BT, ISO tool, has been proved not suitable for high speed machining. There has been HSK, SKI and other high-speed tool in this case.
a high-frequency inverter unit: spindle speed to achieve tens or even hundreds of thousands of revolutions per minute, spindle must be driven by a high-speed high-frequency inverter unit built motor, the output frequency must reach thousands or tens of thousands of hertz.
4. Power Frequency AC motor
a, AC motor power
generally use a three-phase AC motor system, three-phase AC motor as compared with the single-phase motor, both in terms of performance, the use of raw materials and price were significantly superior sex. Same power phase motor is smaller than a single phase motor size, light weight, low price. There are three-phase motor from starting. No single-phase motor starting torque, to start to solve the problem, we need to take some special measures. Single-phase motor torque is a ripple, noise is relatively large, but the power required is relatively simple, especially for use in the home is very convenient. Thus small household electrical apparatus and a multi-phase motor using a single motor.
Second, the AC Motor
Application of frequency inverter is a technology and microelectronic technology, controls the power transmission element by the alternating current motor changing the frequency and amplitude of the motor operating power mode. VVVF AC motor characteristics:
■ percentage of low torque output 180, low-frequency operation characteristics of a good
■ maximum output frequency 600Hz, high-speed motor can be controlled
■ full range of detection protection (overvoltage, undervoltage, overload) instantaneous power failure restart
■ acceleration, deceleration, preventing movement in the stall protection function
■ dynamic parameter automatic motor recognition function, to ensure system stability and accuracy
■ fast response
at a high speed shutdown ■ rich and flexible input and output interface and control, versatility