Research on the positioning control of asynchronous motor - scheme design

 At the beginning of the three-phase ac asynchronous motor brake,the commonly used inverter control,when go downhill to a lower end (e.g.,50 RPM),switch to this system.Due to the ac motor is strong coupling,multi-variable,nonlinear complex controlled object,more difficult to establish accurate mathematical model,and fuzzy control motor magnet does not need to establish a precise mathematical model of controlled object,has strong robustness.In practice,a motor with load is uncertain,but there are a range of.By fuzzy control to determine the location in a certain range.Energy consumption braking of ac motor parts motor is a motor spindle speed is zero,the braking torque to zero as well,so,in the motor brake mode choice with the method of braking energy.

Braking energy: the energy generator generator set consumption of the asynchronous motor brake,the stator winding of the motor from three-phase power source and immediate access to the stator winding dc current.No dc power supply,can be used as shown in figure 1 a circuit;If a dc power supply,can be used as shown in figure b connection mode.Circuit shown in figure 1,the normally open contacts of contactor KM1,when closed to the three-phase ac power supply,motor stator motor running on electric state.For braking energy,can make the power coil,contactor XK acmotortrading.blogspot.com motor from three-phase ac power supply.Immediately make the contactor coil electricity KM2,normally open contacts closed KM2,within two phase winding of the stator flux into the dc power supply.

The mathematical model of permanent magnet synchronous motor

When the permanent magnet synchronous motor stator flux into the three-phase alternating current (ac),the three phase current produced in the stator winding resistance voltage drop.Rotate the armature magnetomotive force produced by three-phase alternating current (ac) and set up the armature magnetic field,Cutting of the acmotor2.blogspot.com stator winding is on the one hand,and produce inductive electromotive force in stator winding;On the other hand with the electromagnetic drive rotor synchronous speed rotation.The armature current will produce only chain fellowship with the stator winding of the stator winding perkins diesel generator magnetic flux leakage,and in the stator winding The leakage is induced emf.In addition,magnetic fields produced by permanent magnet rotor to the stator winding of synchronous speed cutting.

Resulting in a no-load electromotive force.In order to facilitate analysis,the mathematical model is set up,assume the following parameters:(1) to ignore the iron of the motor Heart saturated;(2) regardless of the motor in eddy current and hysteresis losses;(3) the magnetic field generated by the stator and rotor magnetomotive force along the stator inner circle according to the sine distribution,namely ignoring all space harmonics in the magnetic field;(4) of each phase winding is symmetrical,namely each phase winding of the number of turns and electricity Resistance is the same,each phase axis displacement each other the same Angle.Based on the analysis low rpm generator alternator of  the mathematical model of synchronous motor,often using two phase synchronous rotation (d,q) coordinate system and two-phase static coordinate system (alpha,beta).

Figure 1 shows in permanent magnet synchronous motor (d,q) The mathematical model of rotating coordinate system.(1) of the stator voltage equation is:type:r for stator winding resistance;P for differential operator,p = d/dt;Id,IQ for stator current;Ud,uq for stator

voltage;Bits of d,bits of q respectively flux in d,q axis The component;F the rotor angular velocity

omega (omega = omega FNP);Np for motor logarithmic.(2) of the generator stator

stator flux linkage equations as follows:type:bits of f for the rotor flux linkage.(3) the

electromagnetic torque is:type:J is the moment of inertia of the motor.If the electric Motivation for

non-salient pole motor,the Ld = Lq,select id,IQ and motor mechanical angular velocity omega as state

variables,the available state equation of permanent magnet synchronous motor are as follows:by type

(7) can be seen,three-phase permanent magnet synchronous motor is a multivariable System,and the id,IQ,omega nonlinear coupling relationship between,in order to achieve high performance control of three-phase permanent magnet synchronous motor,is a challenging task.