Steady state model control method
Release time:
2021-11-22 19:15
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Steady state model control method
Commonly used steady-state model control schemes include open-loop constant v/f ratio control (ie voltage/frequency = constant) and closed-loop slip frequency control.
This method is an open-loop control method without speed feedback starting from the basic control method of variable voltage and frequency conversion. Because below the rated frequency, if the voltage is constant and only the frequency is reduced, the air gap flux will be too large, causing the magnetic circuit to saturate, and in severe cases, the motor will be burned. In order to keep the air gap magnetic flux constant, the control is carried out in a way that the ratio of the induced potential to the frequency is constant.
Advantages of this method: simple structure, reliable work, low requirements for control and operation speed.
Disadvantages of this method: open-loop control has poor speed regulation accuracy and dynamic performance; only the air gap flux is controlled, but the torque cannot be adjusted, and the performance is not high; because it does not contain current control, it must have a given integral link when starting. In order to suppress the current impact; the torque is insufficient at low frequency, and torque compensation is required to change the low frequency torque characteristics.
(2) Closed-loop slip frequency control
This method is a control method that directly controls the torque. When the motor is running stably, within the range of small slip rate, as long as the motor flux is maintained unchanged, the motor torque is approximately proportional to the slip angle frequency, so controlling the slip angle frequency can control the motor torque .
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Steady state model control method
Commonly used steady-state model control schemes include open-loop constant v/f ratio control (ie voltage/frequency = constant) and closed-loop slip frequency control.
With the development of power electronics technology, microelectronics technology, digital control technology and control theory, the dynamic and static characteristics of the AC drive system are completely comparable to the DC drive system.
The structure of a synchronous motor is roughly the same as that of an alternator. The basic difference between it and an induction motor is that its rotor is a protruding magnetic pole with a coil, and another exciter is used to pick up the direct current and the alternating current)
The induction motor is also called "asynchronous motor", that is, the rotor is placed in a rotating magnetic field, and under the action of the rotating magnetic field, a rotating torque is obtained, so the rotor rotates.
AC motors are composed of a stator and a rotor
AC motors are composed of a stator and a rotor. AC motors are divided into two types: synchronous AC motors and induction motors. In both motors, the stator-side winding is supplied with alternating current to generate a rotating magnetic field, but the rotor winding of a synchronous AC motor usually requires an excitation machine to supply direct current (excitation current); while the induction motor does not need to be supplied with current to the rotor winding.
An AC motor is a device that converts AC electrical energy into mechanical energy. The AC motor is mainly composed of an electromagnet winding or distributed stator winding to generate a magnetic field and a rotating armature or rotor. The motor is made by using the phenomenon that the energized coil rotates under a force in a magnetic field. AC motors are divided into two types: synchronous AC motors and induction motors.
