In 1971,the scholars have put forward the ac motor vector transformation control of new thoughts,new
theory and new technology,its emergence of ac motor control technology research is of epoch-making significance.Because of this through the field-oriented vector transformation of exchange closed loop control system,its control performance can be comparable with the dc system completely.Then,with the power electronics,microelectronics,computer technology and the development of permanent magnetic
material science,the vector control technology application and popularization rapidly.Vector control is in the unified theory of electromechanical energy conversion,motor and developed on the basis of space vector theory,it first used in three-phase induction motor,soon extended to three-phase permanent magnet synchronous motor.Due to the operation of the three-phase induction motor,the rotor heat causes the rotor parameters,and the rotor magnetic field observation depends on the rotor parameters,so the rotor magnetic field is difficult to accurate three phase induction motor observation,make the actual control effect is difficult to achieve the result of theoretical analysis,this is the deficiency of vector control in practice.
The permanent magnet synchronous motor with permanent magnet rotor,parameters are fixed,so the vector control of permanent magnet synchronous motor has been widely applied in low power and high precision.Then,in 1985 permanent magnet motors for saleby Germany ruhr university ockMr.Professor Depenbr first advanced the theory of direct torque control,and then turn it to weak magnetic speed range.Compared with vector control technology,the direct torque control is largely solve the characteristics of the three-phase induction motor vector control is affected by the motor parameters change the problem.Direct torque control was born,in his novel control thinking,system structure of simplicity,good static and dynamic performance has received the widespread attention and got rapid development.At present this technology has been successfully used in the high-power ac drive electric locomotive traction.Germany,Japan,the United States are racing to develop the new technology [3] [4].After the 1990 s,with the wholesalemotor.blogspot.com development of microelectronics and computer control technology,high speed,high integration,low cost and the commercialization of the advent of the microprocessor made it possible to fully digital ac servo system.
Through the microcomputer control,can make the motor speed control performance has greatly
improved,making complex vector control and direct torque control,greatly simplifies the
hardware,reduces the cost,improve the control precision,also can have protection,display,fault
monitoring and diagnosis,the debugging and the reset function.In addition,the change control
strategy,revision control parameters and model also becomes simple,thus greatly improve the
flexibility,reliability and practicability of the system.In recent years,in the advanced digital ac
servo system,many companies have introduced a special chip for motor control.Can quickly complete the system of speed loop,current loop and position loop fast precision adjustment and complex vector
control,to ensure the algorithm for motor control,such as direct torque control and vector
control,neural network control,can the completion of high speed and high precision.Nonlinear
observer and linear quadratic integral control and fuzzy intelligent control and so on all kinds of
new control strategies are constantly emerging,show more III broad prospects.Therefore,the use of
high-performance digital signal processor intelligent digital ac permanent magnet servo control
system is one of the important development direction of ac servo system.
1,the capacitance in circuit "C" and is commonly used in digital representation (such as a capacitor C13 said Numbers for 13). Capacitor is made up of two pieces of metal film,close to the middle separated by electric motors 12 volt insulating material and components. The characteristics of capacitance communication mainly blocking circulation. The size of the capacitance is said to store electrical energy,the size of the capacitance effect is called the capacitive reactance of ac signal,it is associated with the frequency of the ac signal and capacitance.Capacitive reactance XC = 1/2 PI c f (f is the frequency of the ac signal,capacitance c said) is commonly used in telephone with electrolytic capacitor,the kinds of ceramics capacitors,SMD capacitors,monolithic capacitors,tantalum capacitors,polyester capacitors,etc. brake rotor 2,capacitance recognition methods: identification method of capacitance and resistance identification method of basic same,straight standard method,three kinds of color standard method and standard method. 
The basic unit of capacitance with ferrari (F),according to other units include: milli single phase electric motor method (mF),micro method (uF),sodium (nF),leather (pF).Among them: 1 q = 10 3 mm = 10 6 micro method = 9,10 = 10 12 leather method of large capacity capacitor on capacitance directly to mark its capacity values,such as 10 uF / 16 v capacity small capacitance of its capacity value with letters or Numbers on the capacitance letter notation: 1 m = 1000 uF p2 = 1.2 PF 1: n = 1000 PF digital wholesalemotor.blogspot.com representation commonly used three figures show that the size,two significant figures,said before the third digit ratio. Such as: 102 said 10 x 102 = 1000 pf pf said 22 224 x 224 = 0.22 uF pf 3,the capacitance error table F G J K L M allowed error of plus or minus 1% plus or minus 2% plus or minus 5% plus or minus 10% plus or minus 15% plus or minus 20%,such as: a ceramics capacitors for 104 J said capacity of 0. 1 uF,the error of plus or minus 5%.
