Three control modes are usually used in the operation of electric spindle
In the machine tool processing, the electric spindle generally uses the frequency conversion speed regulation method. At present, there are three control methods: General Frequency conversion drive and control, vector control drive and direct torque control. The general frequency conversion is scalar drive and control, the drive control characteristic is constant torque drive, the output power and speed is proportional. General Frequency Control of the dynamic function is not ideal, at low speed control function is not good, the output power is not stable, and does not have c-axis function. But cheap, simple structure, generally used for grinding machines and general high-speed milling machines. The vector control technology imitates the control of the DC motor, and completes the drive and control with the method of the rotor field orientation and vector transformation. The vector control driver has a large torque value when it is just started, and the electric spindle itself has a simple structure and a small inertia, so the acceleration is large, and the allowable limit speed can be reached immediately after starting. The driver has two kinds of open-loop and closed-loop, the latter can complete the response of Azimuth and velocity, not only has better dynamic function, but also can complete the function of c axis; while the former has less dynamic function and does not have the function of C axis, but it's cheaper. Direct torque control (DTC) is a new type of high-function AC speed regulation technology developed after vector control technology. Its control idea is novel, its architecture is simple and clear, and it is more suitable for driving high-speed motorized spindle, it has become a hot technology in the field of AC drive because it can satisfy the requirements of high speed, wide speed regulation, dynamic and static characteristics of high speed motorized spindle.