During the process of machine tool machining, Electric spindleUsually, the method of variable frequency speed regulation is used. At present, the main control methods are: ordinary variable frequency drive and control, vector control drive and control, and direct torque control.

The commonly used variable frequency speed regulation is scalar drive and control, and its drive control characteristics are constant torque drive, with output power proportional to speed. The dynamic performance of ordinary variable frequency control is not ideal, the control performance is poor at low speeds, the output power is unstable, and it does not have c-axis function. But the price is cheap, the structure is simple, and it is generally used for grinding machines and ordinary high-speed milling machines.

Vector control technology imitates the control of DC motors, using rotor magnetic field orientation and vector transformation to achieve drive and control, with good dynamic performance. The vector control driver has a high torque value during startup, while the electric spindle has a simple structure, low inertia, high startup acceleration, and can immediately reach the allowable maximum speed after startup. The latter can achieve feedback on position and velocity, not only with good dynamic performance, but also with c-axis functionality; The former has poor dynamic performance and no c-axis function, but it is cheaper in price.

Direct torque control is a new high-performance AC speed regulation technology developed after vector control technology. Its control concept is innovative, and the system structure is simple and clear. It is more suitable for driving high-speed electric spindles and can meet the requirements of high-speed, wide speed range, and high-speed instantaneous quasi stop static characteristics of high-speed electric spindles. It has become a new type of AC transmission method and a hot technology in the field of information technology.