关键词: 数控机床, 变频, 空载功率, 功率因数, 能耗

Abstract: To reduce the power loss of Computerized Numerical Control (CNC) machine tool during no-load operation，a no-load energy-parameter model of CNC machine tool main transmission system was proposed based on frequency turned by Variable Voltage and Variable Frequency (VVVF).On these basis，the characteristics of no-load energy parameters under no-load operation were analyzed，which included no-load power，no-load current and power factor.The analysis result on the tare power showed that when power supply frequency was less than the base frequency，the tare power increased monotonically with the increase of power supply frequency，whereas when power supply frequency was more than the base frequency，the monotonicity of tare power depended on the parameters of main transmission system.In addition，a sufficient condition was presented for determining whether the minimum of tare power existed or not when the power supply frequency was greater than the base frequency.Furthermore，the analysis result on the no-load current showed that the no-load current increased when the power supply frequency was less than the base frequency and decreased when the supply frequency was greater than the base frequency，and the monotonicity of power factor was parameter-dependent within the whole range of the power supply frequency.The experiments were conducted on a 5-axis CNC machine tool and the result demonstrated the effectiveness of the characteristics of no-load energy parameters.

Key words: computerized numerical control, variable frequency, no-load power, power factor, energy consumption