Vertical lathes are large mechanical equipment used to process large and heavy workpieces with large radial dimensions and relatively small axial dimensions and complex shapes. Such as the cylindrical surface, end surface, conical surface, cylindrical hole, conical hole, etc. of various discs, wheels and sleeves. Threading, spherical turning, profiling, milling and grinding are also possible with the aid of additional devices. The spindle of large machine tools is controlled by D32 inverter to achieve stable speed control, with good low-frequency torque characteristics and fast response speed. Fast braking and stopping are realized by braking unit and braking resistor.