In CNC machine tools, Electric spindleGenerally, frequency conversion speed regulation method is used. At present, there are three main control methods: general variable frequency drive and control, vector control drive and control, and direct torque control. So, what are the differences between these three control methods? Star Wheel will provide a specific comparison for everyone.
Generally, frequency conversion is driven and controlled by scalar drive, and its driving and control characteristics are constant torque drive, with output power proportional to speed. The dynamic function of general frequency conversion control is not ideal, and the control function is not stable at low speeds, with unstable output power and no C-axis function. But the price is cheap and the structure is simple, generally used for grinding machines and general high-speed milling machines.
Vector control skills mimic the control of DC motors, using rotor magnetic field orientation and vector transformation to achieve driving and control, with outstanding dynamic functions. The vector controlled drive has a large torque value at the beginning of the engine, and coupled with the simple structure and low inertia of the electric spindle itself, the engine acceleration is high, which can instantly reach the promised maximum speed after the engine is started. This type of driver has two types: open-loop and closed-loop. The latter can complete the response of azimuth and velocity, not only with better dynamic function, but also with C-axis function; The former has slightly inferior dynamic function and does not have C-axis function, but the price is relatively cheap.
Direct torque control is another new type of high-power communication speed regulation skill developed after vector control technology. Its control idea is novel, the system structure is concise and clear, and it is more suitable for driving high-speed electric spindles. It can better meet the dynamic and static requirements of high-speed electric spindles with high speed, wide speed regulation range, and high-speed instantaneous stop. It has become a popular skill in the field of communication transmission.
By comparison, it can be seen that the direct torque control method is more suitable for the drive of electric spindles. The planned electric spindle direct torque control system has outstanding dynamic and static characteristics. Applying the direct torque control method to the electric spindle drive control system is feasible and more suitable for the fast response requirements of high-speed CNC machine tool drive control systems.