What are the differences between vector control and vf control?

The difference between vector control and VF control is: 1. The characteristics of the two are different. Vector control needs to measure the speed or position of the motor. The accuracy of VF control torque is related to the motor parameters used in the control system. ; 2. The mechanism of action of the two is different; 3. The overview of the two is different.

The operating environment of this tutorial: Windows 7 system, Dell G3 computer.

1. The characteristics of the two are different:

1. Characteristics of vector control: it is necessary to measure (or estimate) the speed or position of the motor. If the speed of the motor is estimated, it is necessary If parameters such as motor resistance and inductance may be used with a variety of different motors, an automatic debugging program is required to measure the motor parameters. By adjusting the control target value, the torque and magnetic flux can change quickly, usually within 5-10 milliseconds.

2. Characteristics of VF control: The accuracy of torque is related to the motor parameters used in the control system, so if the motor temperature changes. The increase in the rotor resistance will cause the error to become larger.

2. The action mechanisms of the two are different:

1. Vector control action mechanism: Speed ​​control (ASR) in vector control uses operating torque Command so that the deviation value between the speed command and the speed detection value (PG feedback or speed estimation value) is 0.

2. VF control mechanism: Speed ​​control during V/f control with PG operates the output frequency to cause the deviation value between the speed command and the speed detection value (PG feedback or speed estimation value) is 0.

3. The overviews of the two are different:

1. Overview of vector control: The technology of using frequency converter (VFD) to control three-phase AC motors, and adjusting the output frequency and output of the frequency converter The size and angle of the voltage are used to control the output of the motor. Its characteristic is that it can control the magnetic field and torque of the motor separately, similar to the characteristics of a separately excited DC motor. Since the three-phase output current and voltage are expressed as vectors during processing, it is called vector control.

2. Overview of VF control: VF control means that the ratio of the output frequency of the inverter to the output voltage is a constant value or proportional. For example, the output voltage is 380V at 50HZ, and the output voltage is 190V at 25HZ, which is constant flux control; the torque is not controllable, and the system is just a single closed-loop control system that uses the physical quantity of rotational speed as a closed-loop, and it can only control the rotational speed of the motor.

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