Not all frequency converters have vector control.

With vector control inverter, the general meaning of motor control is: imitating the speed regulation characteristics of DC motor, the speed of three-phase asynchronous AC motor is adjusted by controlling its two vertical DC magnetic fields.

The following is a block diagram of inverter and motor vector control that I share with you.

For the motor using vector control, it can be divided into two types: non feedback vector control (SVC) and feedback vector control (FVC). No vector control (SVC): because of the speed feedback, it is very troublesome to install additional device of encoder in the motor driven by frequency converter. In this paper, through research, the technical engineers of frequency converter design can calculate the magnetic flux and angular velocity of the motor rotor even if they only need to detect the terminal voltage and working current of the motor, and then calculate the required torque current signal instruction it * and excitation current signal instruction im *, so as to realize the no feedback signal The purpose of vector control.

Then, (FVC) has a feedback vector control, its shaft is installed with an encoder, the encoder will motor speed at any time and anywhere after the detection, sent to the control circuit signal input. Compared with the vector control with feedback, the mechanical torque characteristics of non feedback vector control is much better. So the torque dynamic response ability of the inverter with feedback vector control is worse.

1) As can be seen from the above block diagram, for the frequency converter, given signal processing, in the control circuit, the given signal is simulated and decomposed into two mutually perpendicular DC magnetic field signals. They are called component it * and torque component im *, respectively.

2) According to the technical parameters of the three-phase AC asynchronous motor, a series of equivalent transformations are carried out on the vertical rotating DC magnetic field signals, which are regarded as the control signals ia *, IB *, IC * for controlling the three-phase inverter. When the given signal is changed, the torque component of the DC magnetic field is adjusted to obtain the speed regulation characteristics similar to that of the DC motor.