【正文】 realization [ J ]. Machine tool amp。 speed smooth, wide scope, in 5 Hz ~ 100 Hz range stepless speed regulation。 PCN inverter rated capacity, kVA。 IM: A。 Cos motor power factor ( usually about )。 and adopts the PWM control inverter, rectifier controllable converter, power factor is relatively low, the harmonic pollution is serious, cannot realize energy recycling, in demanding situations, rectifying and inverting process using PWM control of double PWM frequency converter ( 10 ). In the CNC lathe in the experiment system, selection of inverter, inverter current rating is a key quantity. The 4 pole above the motor or motor connected in parallel, must with total current does not exceed the rated current for the principle of frequency converter. CNC machine tool belongs to continuous operation, continuous operation to control the rated capacity and rated current should satisfy the type: ?????????????????????( 4) Type : PM load required motor power output shaft。 considering the harmonic causes the output current increases, the converter drive motor, especially the reactance small highspeed motor, the capacity should be slightly larger than the mon motor selection。 the inverter load performance curve。 variable frequency speed regulation range: 5 Hz ~ 100 Hz stepless speed regulation. The low speed torque smoothing, without creeping phenomenon。 fyFx fyFx VnFy FX = CFx axFyp fyFz the cutting and processing of the heterogeneity of the material, the main motor power should have a certain reserve ( 89 ). Selection of experimental system of Xinxiang City special motor manufacturing pany limited series of 4 YVP variable frequency motor rated power, rated torque of kW, 30 N m, the rated current of 12 A, with similar frequency conversion device matching, interchangeability, general strong, its power, foot mounting FZ = CFzaxFzP ( 3) According to the numerical control lathe experimental system operating conditions, to take: CFz = 40, xFz = 1, yFz = , apmax = 6 mm, Fmax = mm / R, n = 2500 mm / min, d = 30 mm. The cutting power of Pm = Fz, V x 10 3 = x x 10 3 = kW. The study of machine tool transmission efficiency for M = , then the NC machine tool spindle motor power PE Pm / M = kW. Fed by inverter asynchronous motor running condition produced fundamental change ( 7 ), when the motor runs, along with the frequency changer style pressure control, mechanical characteristic curve can be arbitrary translation, which enable asynchronous motor performance is improved greatly. Therefore, CNC Experiment System of variable frequency motor selection, also should be considered : the lathe spindle motor and power characteristics matching problem。 N workpiece speed。 FX feeding force。 CNC lathe 0 Introduction With the development of modern industrial technology, frequency conversion and speed regulation technology in mechanical processing has been widely applied. In the CNC lathe spindle rotary precision of experimental system, determines the ponents the processing precision, frequency speed control of NC machine tool spindle speed, high efficiency, wide range, high precision, the spindle speed is more and more using variable frequency speed regulation. From the spindle speed on the overall system performance indicators, how to select motor and inverter motor and inverter, achieve the best match, the spindle is the key to design of variable frequency speed regulation system. This study focused on the experimental system of NC lathe spindle frequency control system design. 1 the basic principle of frequency conversion AC induction motor speed is: N0 = n ( 1 s ) = 60F ( 1 s ) / P ( 1) Type : F stator power supply frequency, s, slip, P magic pole logarithm. By the formula (1 ) knowledge, change the frequency of the power supply F, motor speed will be adjusted, this is the variable frequency speed regulation. Converter with power semiconductor